Friday, October 30, 2009


33 AZLR 59
(Cite as: 33 Ariz. L. Rev. 59)
Arizona Law Review
Edward J. Imwinkelried [FNa]
Robert G. Scofield [FNaa]
Copyright 1991 by the Arizona Board of Regents;
Edward J. Imwinkelried and Robert G. Scofield
"What the People seek . . . is not an escape from an unfair disadvantage, but the
perpetuation of an unfair advantage." [FN1]
California v. Trombetta [FN2] is one of the leading Supreme Court precedents defining
the scope of an accused's constitutional right to discovery. In Trombetta, the accused was
charged with driving while intoxicated. Shortly after his arrest, the accused submitted to an
Intoxilyzer test to measure his blood alcohol concentration (BAC). The test indicated that the
accused's BAC exceeded 0.10 percent, the level which triggered California's statutory
presumption of intoxication. [FN3] The police could have used the technological
state-of-the-art, a field crimper-indium tube encapsulation kit, to preserve a sample of the
accused's breath. The police, however, neglected to do so.
Before trial, the accused moved to suppress all prosecution testimony about the results
of his Intoxilyzer test. [FN4] The accused argued that the police failure to preserve a breath
sample violated his constitutional right to present a defense. [FN5] If the police had saved a
breath sample, a defense expert could have retested the accused's breath. A retest might have
exculpated the accused by yielding a different, lower BAC. The accused contended that the
government's *60 failure to save a breath sample denied his due process discovery rights. As a
sanction for the denial, the accused urged the Court to suppress all testimony about the
inculpatory intoxilyzers test result.
On certiorari, the Supreme Court rejected the accused's contention. The Court found
that the police acted in good faith; when they tested the accused, it was not apparent to them
that a second breath sample would have been exculpatory. [FN6] Quite to the contrary, since
the initial test was inculpatory, the police were entitled to assume that a retest would have
produced additional incriminating evidence. [FN7] Writing for the Court, Justice Marshall
summarized the evidence that the Intoxilyzer is an accurate scientific test. [FN8] That
evidence convinced the Court "that the chances are extremely low that preserved samples
would have been exculpatory." [FN9] In the Court's judgment, the exculpatory value of the
lost evidence was too speculative and conjectural. [FN10]
Despite the general reliability of the Intoxilyzer, Justice Marshall recognized that it was
possible that a retest of a second breath sample would have been exculpatory. He
acknowledged that the accused had the right to attempt to prove that "the Intoxilyzer results . .
. were inaccurate. . . . " [FN11] The Justice, however, reasoned that the accused had
"alternative means" of attacking the prosecution's Intoxilyzer evidence. [FN12] He gave three
examples. First, the accused could attempt to show "faulty calibration" of the instrumentation.
[FN13] Justice Marshall noted that under state law, the accused had a right to inspect not only
the Intoxilyzer machine itself but also the records of the machine's weekly calibration tests.
[FN14] Second, the accused could try to demonstrate "extraneous interference with machine
measurements." [FN15] The accused could offer evidence that radio waves might have
interfered with the machine or that as part of a diet, he had consumed chemicals which the
Intoxilyzer might misread as alcohol. [FN16] Finally, the accused could try to establish that
there had been operator error. [FN17] The accused had the opportunity to cross-examine the
police officer who conducted the test to prove that the test had been improperly administered.
[FN18] The Justice acknowledged that there must be a fair, adversary *61 balance [FN19] at
trial. However, given these alternatives, that balance could be maintained even though the
accused had been deprived of potentially exculpatory testimony.
Four years later in Arizona v. Youngblood, [FN20] the Supreme Court revisited the
Trombetta issue. In Youngblood, the accused was charged with kidnapping, assault, and
molestation of a young child. After his release by his captor, the child was taken to a hospital.
Hospital personnel collected evidence, including the child's clothing and samples such as saliva
specimens. The personnel included the samples in a sexual assault kit which they properly
refrigerated for preservation. They neglected, however, to take any steps to preserve the
clothing. Although crime laboratory personnel later examined the samples, they failed to apply
certain scientific techniques such as sophisticated genetic marker tests [FN21] "that might have
completely exonerated" the accused. [FN22] There were also body fluid stains on the child's
clothing, but the stains were untestable due to the failure to properly preserve the clothing.
As in Trombetta, the accused in Youngblood argued that he had been denied his
constitutional discovery rights. Once again, the defense argument failed. In the course of the
majority opinion, Chief Justice Rehnquist cited Trombetta and reiterated the Court's earlier
reasoning. [FN24] The Court reaffirmed its belief that "the chances that preserved samples
would have exculpated the defendants were slim." [FN25] In part for that reason, the
unavailability of defense expert testimony about a retest of the samples did not render
Youngblood's trial fundamentally unfair. As in Trombetta, the Court added that while the
accused may not have had the benefit of the ideal evidence of a retest, the accused had
"alternative means" of proof available. [FN26] In the last sentence of his opinion, the Chief
Justice asserted that "the defendant is free to argue to the finder of fact that a . . . test would
have been exculpatory, but the police do not have a constitutional duty to perform any
particular tests." [FN27]
In both Trombetta and Youngblood, the Court assumed that defense evidence
attacking the weight of prosecution scientific testimony would generally be admissible. The
Court plainly assumed that although the trial judge might permit the prosecution to introduce
inculpatory scientific testimony such as an Intoxilyzer test result, the judge would allow the
defense to rebut and respond in kind. That assumption is a vital link in the Court's line of
argument to the conclusion that the accused's inability to retest the physical evidence does not
upset the essential balance and fairness of the adversary system. To be sure, *62 the accused
does not have the best of all possible worlds; the government's destruction or contamination
of the physical evidence precludes the accused from offering retest evidence to show that the
prosecution's earlier test was in error. According to the Court's assumption, however, the
accused can resort to other effective kinds of rebuttal testimony to attack the weight of the
prosecution's test evidence.
The rub is that the Court's assumption is mistaken. When the police destroy or
contaminate the physical evidence after the initial inculpatory test, the accused is necessarily
limited to two types of rebuttal evidence: generalized testimony about the unreliability of the
scientific technique in question or speculative testimony about potential errors by the crime
laboratory technicians in performing the initial test. In Trombetta and Youngblood, the Court
failed to realize that under well-settled doctrines in many jurisdictions, these two types of
evidence are vulnerable to prosecution evidentiary objections. In short, the defense may be
unable to present the rebuttal evidence needed to maintain a fair balance in the adversary
The thesis of this article is that the Court should announce that the accused has a
constitutional right to introduce expert testimony that can generate a reasonable doubt by
impeaching the weight of prosecution scientific evidence. The first part of this article critiques
the Court's assumption in Trombetta and Youngblood that defense rebuttal evidence will be
admissible as a matter of course. This part of the article not only demonstrates that prosecutors
can theoretically object to the admission of defense rebuttal evidence; it also documents that in
some jurisdictions, trial and appellate courts have already sustained such objections. The
second part of the article advances the argument that the Court should restore the balance of
the adversary system by conferring on the accused a constitutional right to introduce expert
testimony attacking the weight of prosecution scientific evidence. The article concludes by
calling on the Court to end the "unfair advantage" [FN28] which the prosecution currently
enjoys because of the Court's mistaken assumption in Trombetta.
In Trombetta situations in which the police destroy or contaminate physical evidence
after an initial inculpatory scientific test of the evidence, the defense's inability to retest the
evidence prevents the accused from offering the best rebuttal evidence. The condition of the
physical evidence makes it impossible for the accused to present a defense expert's testimony
about a carefully conducted second test of the same evidence. The unavailability of the
evidence for retesting forces the accused to resort to two, clearly inferior, types of rebuttal
testimony. The accused can offer generalized [FN29] testimony about the unreliability of the
scientific test. The accused, for example, might attempt to introduce testimony about the test's
inherent margin of error [FN30] or the standard *63 deviations computed in past tests. [FN31]
Alternatively, the accused can proffer more particularized, but more speculative testimony.
Justice Marshall's opinion in Trombetta is suggestive. According to the Justice, the defense
could offer evidence of several factors -- such as the presence of a source of radio waves in the
test area or operator errors -- to attack the weight of the prosecution's Intoxilyzer testimony.
[FN32] Since the defense experts could not retest the physical samples to conclusively
demonstrate that the earlier test was in error, the defense experts can merely conjecture that
the factor in question might have distorted the outcome of the earlier test.
In the past, commentators observed that defense counsel often find it difficult to
introduce evidence attacking the weight of prosecution scientific testimony. [FN33]
Trombetta compounds this difficulty. It is predictable that in some jurisdictions, defense
counsel will find it impossible to introduce the types of evidence that Trombetta forces the
defense to rely on. These types of testimony are vulnerable to three evidentiary objections
[FN34] -- objections which some prosecutors have already made and which some judges have
already sustained. [FN35]
A. The Defense Evidence Attacking the General Reliability of the Scientific Technique
Is Irrelevant Because the General Reliability of the Technique Is Conclusively
It is axiomatic that an item of evidence must be logically relevant to be admissible. In
the words of Federal Rule of Evidence 401, "[e]vidence which is not relevant is not
admissible." [FN36] Suppose, for example, that the prosecution offers scientific testimony to
establish that the accused was driving while drunk. The government charges the defendant
with the violation of a statute proscribing driving with a certain breath alcohol concentration.
The prosecution evidence is a breath alcohol test. In its case-in-chief, the defense offers expert
testimony about the difficulty of converting a breath alcohol reading into a blood alcohol
reading. The trial judge can exclude the testimony as irrelevant. [FN37] The defense
testimony would be relevant if the statute criminalized driving with a certain blood alcohol
level, and the prosecution offered the breath alcohol reading as evidence of the accused's
blood alcohol level. [FN38] In this hypothetical, however, the statute directly criminalizes
driving with a breath alcohol exceeding a specified level. Thus, "there is no need to assume
any conversion ratio between blood alcohol and breath . . . alcohol." [FN39] The *64 defense
expert testimony therefore fails the threshold standard for logical relevance.
In other cases, however, the prosecution opposes the admission of the defense
testimony even though the defense testimony obviously satisfies the threshold test. Assume,
for instance, that the jurisdiction's statute criminalizes driving with a particular blood alcohol
level. Again the prosecution relies on breath test evidence to prove up the offense. As in the
previous hypothetical, the defense offers expert testimony about the difficulty of converting a
breath alcohol reading into a blood alcohol measurement. To convert a breath reading into a
blood alcohol measurement, breath testing devices such as the Intoxilyzer assume that a
person has the same amount of alcohol in one part of blood as he or she has in 2,100 parts of
breath -- a conversion ratio. [FN40] Empirical studies, however, establish that some persons
have ratios higher than 1:2,100 while many have lower ratios. [FN41] When the prosecution
offers breath test evidence to prove a blood alcohol offense, general defense testimony about
the range of conversion ratios is indisputably relevant.
In most jurisdictions, when a defendant is charged with a blood alcohol offense, the
courts not only recognize the relevance of general testimony about the unreliability of the
scientific technique; they construe their drunk driving statutes to permit the defense to
introduce such testimony to attack the weight of prosecution breath test evidence. [FN42]
However, a number of courts come to a contrary conclusion. In these jurisdictions, the courts
found a conclusive presumption regarding the accuracy of breath testing devices -- rendering
general testimony about the range of conversion ratios "irrelevant" and inadmissible.
These courts invoke two theories to justify the exclusion of general rebuttal testimony.
Some courts interpret the governing state statutes as erecting a conclusive presumption
regarding the reliability of the scientific device the prosecution testimony is based on. [FN43]
These courts have concluded that their *65 statutes manifest a conclusive [FN44] legislative
determination [FN45] that the scientific technique is trustworthy. In these jurisdictions, the
statutes render the scientific technique unassailable. [FN46] The courts thus bar general
defense rebuttal evidence as irrelevant. [FN47]
Other jurisdictions rely on a different theory to reach the same result. These courts
point out that when the accuracy of the scientific technique in question is generally accepted,
the reliability of the technique is a proper subject for judicial notice. [FN48] There is authority
that once a judge judicially notices a proposition, "evidence contradicting the truth of the fact
is inadmissible." [FN49] Citing this authority, these courts reason that the judicial notice of the
accuracy of a scientific technique bars the admission of testimony generally attacking the
trustworthiness of the technique. [FN50] The end result is the same as under the statutory
construction theory: Evidence attacking the general reliability of the scientific technique is
deemed irrelevant and inadmissible.
As previously stated, if the police innocently destroy or contaminate physical evidence
after an initial inculpatory scientific analysis of the evidence, Justice Marshall's opinion in
Trombetta allows the prosecution to use testimony *66 about the analysis against the accused
at trial. The Justice's opinion assumes that the accused will be able to maintain a fair
adversarial balance at trial by offering rebuttal testimony. To rebut the prosecution evidence,
the accused might resort to expert testimony about the general untrustworthiness of the
scientific technique. As this subsection has demonstrated, however, in a growing number of
jurisdictions Justice Marshall's assumption is wrong. By invoking a statutory construction or
judicial notice theory, an increasing number of courts hold general defense testimony to be
irrelevant and inadmissible.
B. Under the Rules Governing the Admissibility of Expert Opinions, Defense
Testimony About the Potential Errors in the Initial Analysis of the Physical Evidence
or the Possible Outcome of a Defense Retest Is Inadmissible Because Such Testimony
Is Too Speculative
When the police innocently destroy or contaminate physical evidence after an
inculpatory scientific test, Trombetta leaves the defense only two options. To attack the
weight of the prosecution's scientific test, the defense must offer either: (1) general testimony
about the unreliability of the scientific test, or (2) more specific testimony about the errors the
police criminalist might have committed or the outcome which a defense expert might have
attained if a retest had been possible. The preceding subsection noted the difficulties the
accused faces if the accused chooses option (1). The difficulty of introducing general
testimony in many jurisdictions will pressure defense counsel to select the second option.
Under the rules governing the admissibility of expert opinions in many jurisdictions, however,
the prosecution may be able to block the admission of the more specific testimony. The
Trombetta Court commented on the speculative character of the lost defense evidence. [FN51]
Precisely because of its conjectural character, the admissibility of the defense evidence is
readily assailable. The prosecution may succeed in urging two separate objections to the
defense testimony.
1. The First Objection: The Defense Expert Is Testifying in Response to a Hypothetical
Question, and the Defense Has Failed to Offer Evidence of the Hypothetically Assumed Facts
Assume that the prosecution expert has already testified to the inculpatory scientific
test, or that the prosecution succeeded in introducing a laboratory report of the test under a
hearsay exception such as the business entry doctrine. [FN52] When the expert testifies in
person, the expert will likely claim that he or she "habitually" [FN53] follows proper test
protocol or that they recall complying with the "standard" test procedure on the particular
occasion. [FN54] When the prosecutor offers a laboratory report, the report will probably
contain *67 little information about the test procedures. [FN55] If the report says anything
about test procedures, the report may contain the bald assertion that the analyst followed
"correct" or "accepted" protocol. Given this state of the record, the accused may be hard
pressed to introduce defense rebuttal testimony about potential errors in the prosecution test
or the outcome a defense expert might have achieved on a retest. [FN56]
On this record, the defense expert must testify in response to a hypothetical question.
Under the modern law of expert opinion testimony, there are only three types of permissible
bases for an expert opinion: personally observed facts, hearsay reports customarily considered
by practitioners of the expert's specialty, or the assumptions in a proper hypothetical question.
[FN57] Although an expert may rest an opinion on factual data of which he or she has
firsthand knowledge, [FN58] in Trombetta situations, the defense expert lacks personal
knowledge of the manner in which the prosecution expert conducted the initial test. Most
jurisdictions now permit experts to base an opinion on certain types of hearsay information,
[FN59] but here the defense expert does not even have a hearsay report of any mistakes
committed by the prosecution expert. The defense counsel therefore must attempt to base the
defense expert's opinion on hypothetical assumptions about errors the prosecution analyst
might have committed or a retest the defense expert might have performed.
The record, however, contains no evidence suggesting, much less supporting a finding,
that the prosecution analyst erred in conducting the test. Nor is there any competent evidence
of a defense retest. In Trombetta situations, there can be no retest because the police have
already destroyed or contaminated *68 the physical evidence. An expert may base an opinion
on assumed facts in a hypothetical question only when there is admissible evidence of the truth
of the assumptions. [FN60] There need not be direct evidence of the truth of the assumption,
[FN61] but the assumption must at least be inferable from the evidence in the record. [FN62]
Although most decisions announcing the requirement for proof of the assumption are civil
cases, there are criminal decisions imposing this requirement. [FN63] If the court strictly
applies the requirement for proof of the hypothetically assumed facts, [FN64] the accused will
be unable to introduce the defense expert's rebuttal testimony.
2. The Second Objection: The Defense Expert's Opinion Lacks the Requisite Degree of
Certainty to be Admissible
Assume that the accused overcomes the first prosecution objection to the proposed
defense rebuttal testimony. Under the expert opinion rules, the prosecution can renew the
objection on an alternative ground that the defense expert's opinion lacks the required degree
of certainty to qualify for admission. In most instances, even if the trial judge allows the
defense expert to speculate about the impact of potential errors or the outcome of a possible
retest, the expert will be unable to testify that the error would probably have affected the
outcome of the initial inculpatory test or that a retest would certainly have been exculpatory.
The expert can testify only that the error might have distorted the initial test or that on a retest
an exculpatory outcome would have been a good possibility.
*69 If the defense expert proposes to testify along these lines, the prosecution may
persuade the court to exclude the testimony. The traditional, common-law view required that
the expert vouch that his or her opinion was a reasonable scientific certainty or probability.
[FN65] Under this view, an opinion couched as a mere possibility is automatically
inadmissible. [FN66] The Federal Rules of Evidence do not expressly codify the traditional
view, [FN67] and many courts no longer enforce an invariable requirement that expert
opinions be stated as probabilities or certainties to be admissible. [FN68] In these
jurisdictions, there is no hard-and-fast, categorical rule excluding opinions stated as
A careful reading of the published opinions, however, indicates that, as in the case of
the erroneous report of Samuel Clemens' demise, the reports of the "death" of the traditional,
common-law view are exaggerated. Many courts continue to exclude opinions which fall short
of expressing a probability or certainty. [FN69] There are numerous civil [FN70] and criminal
[FN71] decisions permitting or mandating the exclusion of such opinions. These opinions
have even been excluded in jurisdictions which have adopted the Federal Rules of Evidence.
Some courts cite Federal Rule of Evidence 403 as authority. [FN72] Rule 403 authorizes the
trial judge to exclude relevant evidence when the judge concludes that the attendant probative
dangers substantially outweigh the probative value of the evidence. [FN73] These courts argue
that opinions couched as mere possibilities possess minimal probative worth. Other courts
look to Federal Rule 702 as authority. [FN74] Rule 702 provides that expert opinions are
admissible only when they will assist the trier of fact. [FN75] These courts contend that an
opinion stated as a mere possibility will be unhelpful to the jury.
Like the requirement for independent proof of hypothetically assumed facts, courts'
reluctance to admit expert opinions couched as possibilities may prove to be an
insurmountable barrier for an accused offering expert testimony to attack the weight of
prosecution scientific evidence. Before the defense *70 expert states a final opinion, the
prosecutor can take the witness on voir dire [FN76] and force the expert to concede that her
opinion falls short of probability or certainty. Armed with that concession, the prosecutor can
then argue that the opinion is inadmissible. It is predictable that, in some cases, the argument
will prevail. [FN77]
C. The Trial Judge Has Discretion to Exclude Defense Rebuttal Testimony When the
Trial Judge Concludes that the Probative Dangers Incidental to the Admission of the
Testimony Outweigh the Probative Value of the Testimony
The last subsection noted that the prosecutor may convince the trial judge to exclude
the defense rebuttal testimony solely because of the speculative character of the testimony.
Even if the judge is unwilling to bar the testimony on that ground alone, the speculative
character of the testimony gives rise to another prosecution argument. The prosecutor can
invoke the common-law legal relevance doctrine [FN78] or the modern codification of the
doctrine, Rule 403, in a Federal Rules jurisdiction. Rule 403 reads:
Although relevant, evidence may be excluded if its probative value is substantially
outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury,
or by considerations of undue delay, waste of time, or needless presentation of cumulative
evidence. [FN79]
Suppose that in our hypothetical the trial judge overrules the prosecutor's objection that
under the expert testimony rules, the defense witness' opinion is automatically inadmissible
because the opinion is too speculative. The prosecutor can nevertheless argue that the judge
should factor the speculative character of the testimony into a discretionary balancing under
Rule 403. Like the preceding prosecution objections, this argument has a decent prospect for
1. The Probative Value Component of Rule 403 Balancing
The prosecutor is certainly correct in arguing that the judge may consider the
speculative character of the defense testimony in assessing the probative value of the
testimony. Virtually all courts and commentators agree that in gauging probative worth under
Rule 403, the judge may consider the facial vagueness or uncertainty of the proposed
testimony. [FN80] A certain or probabilistic opinion possesses more probative value than one
couched as a possibility. Thus, the unavoidably speculative character of the defense testimony
cuts against its admissibility under Rule 403.
*71 If the accused relies on testimony about the general unreliability of the scientific
technique rather than more particularized, speculative testimony about the mistakes the
laboratory technician might have committed, the prosecutor can argue that the circumstantial
character of the testimony diminishes its probative value. Courts and commentators also
concur that in Rule 403 analysis, the judge may consider the circumstantial character of the
evidence. [FN81] The ultimate issue to be resolved by the trier of fact is whether the
technician followed test protocol on the specific occasion when the technician analyzed the
physical evidence in question. In Trombetta cases, the accused rarely has direct evidence of an
error by the technician. General testimony about the untrustworthiness of the scientific
technique is merely circumstantial proof that the outcome of the initial police test was in error.
Even if the jury believes the general testimony, the jury must make a further inference as to
the specific test the technician conducted. The larger the number of intermediate inferences
the jury must draw, the greater the probability that the jury will commit inferential error, and
the lower the probative worth of the evidence. [FN82] To bolster its argument under Rule
403, the prosecution can point to favorable language in several New Jersey opinions. In one
case, the New Jersey Supreme Court stated that the probative value of general testimony about
the unreliability of the Drunkometer was "almost nil." [FN83] In another case, the same court
asserted that general testimony about the unreliability of the breathalyzer "has negligible
probative value." [FN84]
2. The Probative Danger Component of Rule 403 Balancing
The judge's assessment of the probative value of the evidence is only the starting point
in Rule 403 analysis. The judge must also identify the probative dangers that may outweigh the
probative value. [FN85] In Trombetta cases, the prosecutor can frequently make a plausible
case that probative dangers substantially outweigh the probative worth of the defense
testimony. The probative dangers, listed in Rule 403, include the risks of "confusion of the
issues" [FN86] and "undue delay . . . [or] waste of time." [FN87]
In several cases in which prosecutors offered scientific evidence, prosecutors objected
to the admission of defense rebuttal testimony because that testimony was "confusing."
[FN88] In the Brayman case, the Washington Supreme Court noted that one of the state
legislature's motivations for amending that jurisdiction's drunk driving statutes was a desire "to
eliminate defense experts' testimony about blood-breath ratios." [FN89] The legislative history
of the statute suggested to the court that the legislature had a justifiable fear that such defense
*72 testimony would "confus[e] the jury." [FN90] The prosecutor's objection seems especially
credible in Trombetta cases when the defense expert attempts to testify about errors the police
technician might have committed or the outcome of a possible retest. Jurors could
conceivably find it difficult to sort the testimony about what the technician did, what the
technician might have done, and what a second analyst could have done during a retest.
A prosecutor might also argue that the presentation of the defense rebuttal testimony
would be time-consuming. In Brayman, the court indicated that the state legislature was also
concerned that attacks by defense experts on the weight of prosecution scientific evidence
"dragg[ed] things out" [FN91] at trial. Trial and appellate courts alike are familiar with the
horror stories of drawn out "battles of the experts" at trial. [FN92] In one case, the accused
objected to the admission of an electrophoretic analysis of dried bloodstains. [FN93] The
testimony about the reliability of electrophoresis consumed eight days of court time. [FN94]
In another case involving a challenge to the admissibility of moving radar speedmeter
evidence, the scientific testimony about the trustworthiness of moving radar required "over
2,000 pages" of trial transcript. [FN95] In the most famous DNA case to date, People v.
Castro, [FN96] there were "approximately five thousand pages" of testimony and argument
over the reliability of the DNA evidence, in particular the manner in which the laboratory
technicians applied DNA typing technology in that case.
If the prosecutor persuades the trial judge to exercise discretion under Rule 403 to
exclude defense rebuttal testimony, on appeal the accused will find it difficult to persuade an
appellate court to reverse. The appellate courts give the trial judge broad latitude [FN97] and
accord great deference to the trial judge's decision. [FN98] The appellate courts appreciate that
balancing probative value against probative danger is a Procrustean task. [FN99] The trial
judge cannot quantify the competing considerations. [FN100] The trial judge is in the position
of a metaphysician weighing intangibles. [FN101] As a practical matter, appellate courts rarely
second-guess trial court decisions under Rule 403. [FN102]
In Trombetta, the Supreme Court proceeded on the assumption that as a general
proposition, even when the police innocently destroy or contaminate physical evidence after an
initial inculpatory scientific test, the accused will have a fair opportunity to rebut the
inculpatory test result at trial. The Court assumed that the rebuttal testimony would be
admissible. As Section I demonstrated, however, in many cases the Court's assumption will
prove to be mistaken. The unavailability of the physical samples for retest forces the defense
to fall back on two types of rebuttal evidence: general testimony about the unreliability of the
scientific technique in question and more specific, but speculative testimony about the initial
test and a potential retest. These kinds of rebuttal testimony are vulnerable to prosecution
objections under the statutory and decisional evidence law in many jurisdictions.
Defense counsel recently began to realize the evidentiary problems caused by
Trombetta. To surmount those problems, they are now arguing that they have a constitutional
right to override the statutory and decisional evidence law in their jurisdiction and introduce
the rebuttal testimony. Most courts have flatly rejected this argument. [FN103] A few judges,
however, have agreed that the defense argument has merit. By construing state statutes to
permit the admission of defense rebuttal evidence, some courts have endeavored to moot the
defense argument. [FN104] In other cases, dissenters argued in favor of the existence of such
a constitutional right. [FN105] In still other cases, the courts recognized the right in dictum.
[FN106] Most importantly, however, a handful of cases from Alaska, California, and Hawaii
squarely hold that the accused has this constitutional right. [FN107]
The thesis of this article is that this emerging line of authority reaches the right result.
In Trombetta, the Court expressed its concern for the maintenance of a fair, adversary balance
in the criminal justice system. The Court believed *74 that the balance could be maintained
because the accused supposedly has "alternative means" available to rebut the prosecution
evidence. [FN108] But as we have seen, the prosecution can upset the balance by blocking the
admission of defense rebuttal testimony in many jurisdictions. The most direct method of
reinstating the balance is to constitutionalize the accused's right to present the rebuttal
evidence. The cases supporting this right have taken that step.
However, to date all the cases in the line of authority suffer from a common weakness:
the failure to articulate a sound doctrinal basis for the recognition of the constitutional right.
In one case, the court summarily announced that the exclusion of the rebuttal evidence was
"unconstitutional." [FN109] Another court was content to declare in conclusory fashion that
the exclusion denied the accused "a fair trial." [FN110] At most, the courts invoked "due
process" as the source of this constitutional right. [FN111] The balance of this article attempts
to place this line of authority on a sounder doctrinal footing by rationalizing the result under
the accused's implied sixth amendment right to present reliable, critical evidence. [FN112] The
following subsection presents the prima facie case for extending the accused's sixth
amendment right to defense testimony rebutting prosecution scientific evidence. The second
subsection demonstrates that the courts have already applied the accused's sixth amendment
right to override the very types of evidentiary objections which prosecutors are now invoking
to bar the admission of defense rebuttal testimony.
A. The Prima Facie Case for Extending the Accused's Sixth Amendment Right to
Defense Expert Testimony Attacking the Weight of Prosecution Scientific Evidence
Before 1967, statutory and common-law evidentiary rules were generally invulnerable to
constitutional attack. The Supreme Court had not identified a constitutional theory for
evaluating the validity of the rules. In 1967, however, the Court rendered its landmark decision
in Washington v. Texas. [FN113] Washington was charged with murder. Another man named
Charles Fuller had already been convicted of the same killing. At his trial, Washington
attempted to call Fuller as a witness. Washington's attorney made an offer of proof that
Fuller's testimony would exculpate Washington. The prosecutor, however, objected on the
basis of two state statutes. The statutes provided that persons charged or convicted as
co-participants in the same offense could not testify for one another. The trial judge sustained
the prosecutor's objection, and a conviction followed.
In Washington, the Court held that the application of the statutes to bar Fuller's
testimony violated Washington's constitutional rights. Chief Justice Warren wrote for the
majority. As a threshold matter, Warren held that the fourteenth amendment due process
clause incorporates the sixth amendment *75 compulsory process guarantee. Warren next
ruled that as a necessary implication from the express compulsory process guarantee, the
accused has an implied right to present critical exculpatory testimony. Warren used reductio ad
absurdum reasoning to justify the ruling; he asserted that it would be nonsensical to grant an
accused a right to summon witnesses whom he could not even call to the witness stand. The
Chief Justice stated that under the sixth amendment, the accused has a constitutional "right to
put on the stand a witness who [is] physically and mentally capable of testifying to events that
he has personally observed, and whose testimony [is] relevant and material to the defense."
Washington dealt with a broad incompetency doctrine which purported to bar
testimony by certain types of defense witnesses altogether. Because the case involved a
blunderbuss incompetency doctrine, the Chief Justice's opinion left unanswered the question
of whether the new sixth amendment right spends its force by placing the witness on the
stand. "Did the right expend its force when it placed the defense witness on the stand? After
the [accused] seated his witness, was he then bound by whatever exclusionary rules the
legislatures and courts chose to apply" to the substance of the witness' testimony? [FN115] Or
could the accused also invoke the right to attack evidentiary rules with a more limited
exclusionary impact than an incompetence doctrine -- rules such as hearsay which regulate the
content of a witness' testimony? Many lower courts answered that question in the negative.
[FN116] As the Illinois Supreme Court stated in a post-Washington decision, "[t]here is no
suggestion in Washington that the admission of inadmissible hearsay is constitutionally
required." [FN117]
The Supreme Court confounded the lower courts by its 1973 decision in Chambers v.
Mississippi. [FN118] Like Washington before him, Chambers stood trial for murder. His
theory of the case was that the real murderer was Gable McDonald. McDonald told three
acquaintances that he perpetrated the crime. At trial, Chambers attempted to introduce the
three acquaintances' description of McDonald's statements. Citing the hearsay rule, the
prosecutor objected. The defense countered that McDonald's statements fell within the
declaration against interest hearsay exception. The prosecutor, however, contended that
Mississippi hearsay doctrine adhered to the hoary, common-law view admitting only
declarations against pecuniary or proprietary interest. The prosecutor argued that McDonald's
statements were inadmissible because they disserved only his penal interest. The trial judge
sustained the objection.
After the state courts affirmed Chambers' conviction, the Supreme Court granted
certiorari to decide, inter alia, [FN119] whether the trial judge's exclusion of the hearsay
evidence was unconstitutional. The Court specifically cited *76 Washington [FN120] as
authority for its conclusion that the trial judge's evidentiary ruling was constitutionally infirm.
Writing for the majority, Justice Powell found that McDonald's statements were demonstrably
reliable. The patently disserving character of the statements, their sheer number, and the
presence of some corroboration of McDonald's guilt "provided considerable assurance of [the]
reliability" of McDonald's statements. [FN121] Further, given Chambers' theory of defense,
the excluded hearsay was "critical." [FN122]
In subsequent decisions, the Supreme Court and the lower courts have elaborated on
the scope of this implied sixth amendment right. [FN123] The courts have gone to great
lengths in enforcing that right. The courts, for example, have allowed accused to introduce
testimony otherwise barred by the attorney-client privilege, [FN124] the medical privileges,
[FN125] rape shield laws, [FN126] and various restrictions on the admissibility of
impeachment evidence. [FN127]
Some of the cases recognizing the accused's constitutional right to present rebuttal
testimony attacking prosecution scientific evidence make the sweeping assertion that the
accused has a "constitutional right to present all relevant evidence in his defense to the crime
with which he is charged." [FN128] Although the courts have gone far in protecting the
accused's sixth amendment right, that assertion overstates the extent of the right. It would
trivialize that right -- and revolutionize criminal evidence law -- to extend the right to "all
relevant" defense evidence. The right is more limited. To trigger the right, the accused must
establish two things. First, the accused must show that the evidence is highly material to the
case. Courts generally confine the scope of the right to important or "crucial" evidence.
[FN129] The trend in the case law is to apply the constitutional right to an item of defense
evidence only if the item might generate reasonable doubt and affect the outcome of the trial.
[FN130] In addition, the accused must make at least a minimal showing that the evidence is
trustworthy. [FN131]
1. The Materiality Prong
In many cases, an accused offering rebuttal evidence to attack prosecution scientific
evidence will be able to make the requisite showing. In a high percentage of the cases, the
accused can demonstrate the requisite materiality. Crime laboratory facilities are overburdened.
[FN132] Prosecutors typically do not *77 go to the length of obtaining scientific evidence
unless the evidence will help the prosecutor prove an important element of the charged
offense. If the prosecution relies heavily on scientific evidence to prove such an element, even
minimally probative defense rebuttal testimony can generate the reasonable doubt the accused
needs to gain an acquittal.
In Judge Weinstein's famous survey of the federal trial judges in the Eastern District of
New York, he attempted to determine their understanding of the standard of proof beyond a
reasonable doubt. [FN133] The overwhelming majority responded that they equated the
standard with a probability exceeding eighty- five percent. A significant number of the judges
indicated that in their mind, the standard requires proof exceeding a ninety percent probability.
Defense rebuttal testimony raising a fifteen percent or even ten percent probability of
innocence might result in an acquittal. Defense rebuttal evidence raising any significant doubt
about the reliability of the prosecution's scientific testimony should therefore satisfy the
materiality prong of the test for triggering the accused's implied sixth amendment right.
Often, the accused will be able to establish such a significant doubt. There is a massive
amount of hard evidence that misanalysis is common at forensic laboratories. [FN134] The
published proficiency studies document an alarmingly high error rate. The Forensic Science
Foundation conducted proficiency tests of questioned document examiners. [FN135] The
percentages of error were in the double figures rather than in the single digits. [FN136] The
incidence of error was so high that defense rebuttal testimony about these error rates could
easily give a rational juror "cause for concern" if the prosecution relies primarily or exclusively
on questioned document testimony to prove the defendant's identity as the perpetrator.
[FN137] The prosecution often offers evidence of an immunoassay test of the accused's urine
to establish that the accused had consumed a contraband drug. According to two researchers
for the Office of Technology Assessment of the United States Congress, the proficiency
studies of the immunoassay laboratories reveal that "error rates continue to be high." [FN138]
A study conducted by the Centers for Disease Control (C.D.C.) yielded especially disturbing
findings. [FN139] One of the laboratories participating in the C.D.C. study reported
erroneous results on 66.5 percent of the 160 samples analyzed. Whenever the defense can
demonstrate such high error rates for the scientific technique the prosecution is relying upon,
the accused meets the materiality prong for invoking the sixth amendment right.
It is true that in almost all Trombetta cases, the defense expert must stop short of
stating an opinion couched as a certainty or probability. But because the prosecution has the
onerous burden of establishing guilt beyond a *78 reasonable doubt, [FN140] the accused can
be acquitted by establishing even a good possibility of innocence. When the prosecution relies
heavily on its scientific evidence to prove an essential element of the charged offense, a
defense expert's opinion couched as a possibility can easily suffice to raise a reasonable doubt.
The opinion would thus satisfy the materiality prong.
2. The Reliability Prong
The second prong mandates that the accused come forward with evidence establishing
the trustworthiness of the rebuttal testimony. The lower courts split on the question of the
required showing of reliability. [FN141] Some courts use Chambers as a benchmark and
demand an impressive showing that the defense evidence in question is trustworthy. [FN142]
In Chambers, the inference of the reliability of McDonald's hearsay statements was
overpowering; several factors, including the number of McDonald's incriminating statements,
pointed to the conclusion that his statements were trustworthy. The better view, however, is
the position championed by Professor Westen. Professor Westen, the leading contemporary
authority on the sixth amendment, has argued that the standard is laxer, essentially equivalent
to the standard the Court employs to determine the admissibility of prosecution evidence
under the confrontation clause. [FN143] In Chambers, the Court cited some of its earlier
decisions evaluating the trustworthiness of prosecution hearsay under the confrontation clause
as examples of showings of reliability sufficient to trigger the accused's sixth amendment right.
[FN144] "Chambers stands for the proposition that evidence that is sufficiently reliable by
constitutional standards to be introduced 'against' the accused is sufficiently reliable to be
introduced 'in his favor."' [FN145] When accused have challenged the reliability of
prosecution evidence under the confrontation clause, the Court has accepted relatively minimal
showings of the trustworthiness of the evidence. [FN146]
As in the case of the materiality prong, the accused will often be able to satisfy the
reliability test for triggering the accused's sixth amendment right. Suppose that the accused
offers a defense expert's testimony about the general unreliability of a scientific technique such
as evidence of the technique's inherent margin of error. [FN147] The accused can validate the
testimony by eliciting the defense expert's testimony that many, well-designed experiments
have verified the margin of error. [FN148] Or assume that the accused attempts to *79
introduce a defense expert's more specific testimony that the police analyst might have
committed a particular type of error in conducting the test and that that error might have
skewed the result. The accused could establish the reliability of this testimony by showing that
in proficiency studies conducted by reputable testing agencies such as the Centers for Disease
Control, the particular error is commonplace and frequently results in erroneous outcomes.
B. The Application of the Accused's Sixth Amendment Right to the Types of
Evidentiary Doctrines Which Prosecutors Invoke to Block the Admission of Defense
Rebuttal Testimony
Even though the accused can construct a prima facie case for extending the sixth
amendment right to the defense rebuttal testimony, the trial judge can sometimes justifiably
exclude the testimony. The judge's conclusion that the accused has satisfied the materiality and
reliability prongs does not end the analysis. The accused's sixth amendment right is not
absolute. [FN149] In the Washington-Chambers line of authority, the Court has developed a
balancing test to determine whether the accused's sixth amendment right overrides the
jurisdiction's statutory and common-law evidentiary rules. [FN150] After the accused makes
out a prima facie case for invoking the right, the judge must identify the competing
government interest, that is, the rationale for the evidentiary rule. The judge then balances that
interest against the accused's right. [FN151] Thus, even when the accused can make out a
prima facie case, it is not a foregone conclusion that the accused's sixth amendment right will
prevail over the evidentiary rules cited as bases for excluding defense rebuttal testimony. For
several reasons, however, the accused's contention has an excellent chance of success.
One reason is the prevailing view that when the judge has a bona fide doubt about the
proper way to strike the balance between the competing interests, "[t]he scales . . . are weighted
in favor of the accused." [FN152] One commentator observed that the Supreme Court has
"consistently" struck the balance in the accused's favor. [FN153] In the decided cases, the
scales appear to be "loaded" in the accused's favor. [FN154] The appellate courts send trial
judges a clear signal that in a "close" case, the judge should admit the defense testimony.
[FN155] The Supreme Court twice upheld the accused's right even though doing so *80
necessitated overriding an evidentiary rule that was then the majority rule in the United States.
[FN156] The cases teach that "doubts or borderline cases should be resolved in [the accused's]
favor." [FN157] While still a circuit judge, Justice Kennedy wrote that the prior cases "tip the
scales in favor" of the accused's sixth amendment right. [FN158]
Another reason is that the courts have already invoked the right to override the very
types of evidentiary rules that prosecutors invoke to block the admission of defense rebuttal
testimony in Trombetta cases.
1. Logical Relevance Rules
As Section I pointed out, in some jurisdictions the courts developed judicial notice and
statutory construction theories for excluding defense testimony about the general unreliability
of scientific techniques employed by police criminalists. These courts find a conclusive
legislative or judicial determination that the technique is valid and rule the defense testimony
When the defense testimony passes muster under the materiality and reliability prongs,
that ruling violates the accused's sixth amendment right. Concededly, government branches
such as the legislature and judiciary have wide latitude in defining crimes. [FN159] A
legislature can decide, for example, to criminalize the act of driving with a certain breath
alcohol concentration as well as driving with a particular blood alcohol level. [FN160]
However, even if the legislature defines the criminal offense as operating the vehicle with a
certain breath alcohol concentration, the breath test itself is not an element of the offense. It is
merely evidence which the prosecution uses to prove the accused's commission of the
forbidden act. [FN161]
It violates the accused's sixth amendment right to immunize prosecution evidence from
rebuttal by defense testimony which satisfies the materiality and reliability prongs. When
Congress passed on the proposed Federal Rules of Evidence, Congress assumed that it would
be unconstitutional to instruct a jury that the jury must accept as conclusive a judicially noticed
proposition such as the validity of a scientific technique. Congress amended Federal Rule
201(g) to explicitly state that jurors are "not required . . . to accept as conclusive any *81 fact
judicially noticed." [FN162] Congress added the amendment because it believed that treating a
judicially noticed fact as conclusive in a criminal case would be "contrary to the spirit of the
Sixth Amendment. . . . " [FN163] Several courts have voiced the same belief. [FN164]
Most importantly, the Supreme Court's 1986 decision in Crane v. Kentucky [FN165]
lends support to the belief. In Crane, the accused made a pretrial motion to suppress his
alleged confession. At the hearing, the accused introduced evidence of the circumstances
surrounding the statement. The trial judge denied the motion. At trial, the prosecution
introduced the confession. The accused then attempted to introduce some of the same
evidence to attack the weight of the confession. The prosecutor objected to the admission of
the evidence on relevance grounds, and the trial judge sustained the objection.
On certiorari, the Supreme Court reversed. Citing Trombetta at the outset of its
opinion, the Court emphasized that the accused has a "fundamental constitutional right to a
fair opportunity to present a defense." [FN166] The Court then cited both Washington and
Chambers for the proposition that the general constitutional right subsumes the more specific
right to present favorable evidence. [FN167] The Court independently reviewed the question
of whether the defense evidence in question was relevant to the evaluation of weight to be
given the accused's confession. [FN168] After its de novo review of the evidence, the Court
concluded that the evidence was logically relevant and that its exclusion amounted to
constitutional error.
Crane is a significant extension of the Chambers line of authority. In cases such as
Chambers and Washington, the excluded defense evidence was logically relevant to the
historical merits of the case. In both cases, the evidence tended to show that someone other
than the accused was the perpetrator. In Crane, however, the excluded evidence had no
relevance to the historical merits. It was relevant only to attack the weight of prosecution
evidence, the accused's confession. Crane thus stands for the proposition that the accused's
sixth amendment right attaches to defense testimony which is relevant only to the rebuttal of
damning prosecution evidence. Under Crane, the right therefore applies to defense expert
testimony offered to attack the weight of prosecution scientific evidence. Moreover, under
Crane the court is obliged to make an independent assessment of the logical relevance of the
defense evidence. The Crane Court undertook a de novo review of the relevance of the
evidence; [FN169] and when the issue arose in other contexts, the Court has exercised the
right to *82 independently assess the logical relevance of evidence. [FN170] Thus, a court
cannot shirk that responsibility and routinely defer to an earlier determination -- either judicial
or legislative -- that the evidence in question is irrelevant.
2. Expert Testimony Rules
Just as the accused can rely on the sixth amendment right to attack the exclusion of
defense evidence as irrelevant, the accused can invoke the right to invalidate the exclusion of
the evidence under the expert testimony rules. After Chambers, numerous courts invoked the
right to mandate the admission of various types of expert opinion testimony. A few courts
recognized an accused's right to introduce exculpatory polygraph test results. [FN171] A larger
number of courts relied on the sixth amendment right in holding that an accused had a
constitutional right to introduce various forms of psychiatric and psychological testimony.
he Supreme Court's 1987 decision in Rock v. Arkansas [FN173] strengthens the
argument for applying the sixth amendment to restrictions on the admissibility of expert
testimony. The accused, Vickie Rock, was charged with homicide. Before trial, she had
difficulty remembering the details of the shooting. She twice underwent hypnosis to revive her
memory. Only after hypnosis did she remember the critical detail that her gun had accidentally
misfired. The prosecutor filed a pretrial motion to exclude the accused's hypnotically refreshed
testimony. The trial court granted the motion, and the state supreme court affirmed. The state
court concluded that hypnotically enhanced testimony is so untrustworthy that it is per se
inadmissible. [FN174] Per se inadmissibility was apparently the majority view in the United
States at the time. [FN175]
On appeal, the accused challenged the exclusion of her testimony. The Supreme Court
sustained her challenge. [FN176] Justice Blackmun wrote for the majority. He began his
analysis by citing Washington. [FN177] Under Washington, the accused has a right to call
witnesses, including herself. [FN178] The Justice next conceded that the state has a legitimate
interest in protecting the integrity of the fact-finding process by excluding unreliable evidence.
He also frankly admitted *83 that "[t]he use of hypnosis in criminal investigations . . . is
controversial, and the current medical . . . view of its appropriate use is unsettled." [FN179]
After reviewing the scientific literature, however, he concluded that the prosecution failed to
show that "hypnotically enhanced testimony is always so untrustworthy . . . that it should
disable a defendant from presenting her version of the events." [FN180]
Since the Court's decision in Rock, the lower courts and commentators have assumed
that the accused's sixth amendment right applies to scientific evidence. Some commentators
have expressly concluded that Rock applies to scientific techniques other than hypnotic
memory enhancement. [FN181] Courts have also cited Rock as the basis for admitting novel
types of defense expert testimony such as evidence of a portable breathalyzer test. [FN182]
It is, however, possible to limit Rock to its facts. In Rock, the evidence the accused
attempted to present to the jury was her own lay testimony about the shooting. She did not
attempt to introduce any expert testimony about the reliability of the hypnotic enhancement
technique. But it would be illiberal to limit Rock in this fashion. The primary focus of Justice
Blackmun's opinion was the state of the scientific record on the reliability of testimony
produced by hypnotic enhancement. His immediate concern may have been the reliability of
the testimony produced in court, but in turn the reliability of that testimony depended on the
validity of the scientific methodology used to produce the testimony.
It is especially appropriate to apply the accused's sixth amendment right to defense
rebuttal testimony. Repeatedly, the courts assert that the primary danger posed by expert
testimony is that the lay jurors will overestimate the probative value of the testimony. [FN183]
The California Supreme Court voiced the fear that expert testimony may "cast a spell" over
the jury. [FN184] The same court also stated that a "misleading aura of certainty . . . often
envelops a . . . scientific process." [FN185] The District of Columbia Court of Appeals
asserted that jurors often attribute a "mystic infallibility" to scientific evidence. [FN186]
Similarly, the Maryland Court of Appeals wrote that jurors naively overestimate the objectivity
and certainty of expert testimony. [FN187]
The courts' concern about this supposed danger helps explain many of the restrictions
on the admissibility of expert testimony. Section I pointed out that *84 in some jurisdictions,
prosecutors can object to defense testimony on the ground that the defense expert's opinion
lacks the requisite degree of certainty. The requirement for a certain degree of certainty in the
expert opinion relates to this supposed danger:
[The courts] fear that the lay jurors will assume that virtually all scientific testimony is
infallible. If we work from that premise, it makes sense to limit expert testimony to opinions
that merit the weight we think that jurors will accord the opinions. If jurors are likely to give
scientific evidence certain or conclusive weight, it is arguable that only scientific opinions of
that degree of certitude should be admitted. [FN188]
Similarly, the limitations on the use of hypothetical questions are partially attributable to
this fear. Many, if not most, courts assume that jurors tend to uncritically credit the ultimate
opinion stated by an expert; [FN189] awed by the witness' stature as an expert, the jurors may
be inclined to accept the ultimate opinion merely because ipse dixit. Suppose that there is no
evidence of the truth of a particular assumption underlying the expert's opinion. The courts
suspect that even if an expert acknowledges that his opinion rests on a purely hypothetically
assumed fact, the jury might accept the opinion. The net result would be that the jury would
overvalue the opinion. Like the courts' insistence on opinions couched as probabilities or
certainties, the requirement for proof of the assumed facts represents an effort to ensure that
the expert opinions admitted in court possess the great weight which jurors presumably ascribe
to them. Before the court will permit an expert to opine based on an assumed fact, there must
be some evidence that the assumption is correct.
Thus, the overarching concern inspiring the expert testimony rules is preventing the
jury from overestimating the probative value of expert testimony. It is Catch 22 reasoning to
invoke the rules to exclude defense rebuttal testimony. The accused's rebuttal testimony does
not present that risk. The risk is most acute when the prosecution introduces scientific
evidence and the defense is denied an opportunity to offer expert testimony to rebut the
scientific evidence. If unrebutted, prosecution scientific evidence presents a grave risk that the
jury will overvalue the evidence. The exclusion of the defense rebuttal testimony compounds
the risk. But, the admission of the testimony will counteract the risk. In sum, when defense
rebuttal testimony satisfies the materiality and reliability prongs for triggering the accused's
sixth amendment right, it will usually be wrong-minded to mechanically invoke the expert
testimony rules to bar the defense testimony.
3. The Legal Relevance Doctrine Under Rule 403
Like the logical relevance and expert testimony rules, the legal relevance doctrine has
succumbed to attack under the accused's sixth amendment right. [FN190] The best example is
the Supreme Court's 1988 decision in Olden v. *85 Kentucky. [FN191] Olden, a black man,
was charged with raping a Ms. Matthews, a Caucasian woman. At trial, the accused offered
evidence that Ms. Matthews was having an affair with another black man, Mr. Russell. The
accused attempted to introduce the evidence to bolster his theory that Ms. Matthews had
consented to intercourse with him, later realized that Russell would be jealous, and finally
"concocted the rape story to protect her relationship with Russell. . . . " [FN192]
The prosecutor objected to the defense evidence on legal relevance grounds. The trial
judge sustained the objection. The trial judge stated that the evidence had extreme potential
for prejudice in the technical sense under the legal relevance doctrine. If the evidence were
admitted, it might generate "extreme prejudice against Matthews" [FN193] in the jury's mind
and tempt them to decide the case on an improper basis. [FN194] A bigoted juror might
improperly discount Ms. Matthews' credibility simply because she was involved in an interracial
affair. The Court acknowledged that in applying the legal relevance doctrine, a trial judge has a
measure of discretion. Nevertheless, the Court held that the exclusion of the defense evidence
was unconstitutional. The Court emphasized that Matthews' testimony was "central, indeed
crucial, to the prosecution's case." [FN195] The Court struck the balance in the accused's
favor because the evidence in question had great potential to demonstrate the falsity of
Matthews' testimony. [FN196]
Olden makes it far more difficult for trial judges to justify the exclusion of defense
rebuttal evidence under the rubric of legal relevance. In Olden, the trial judge's fear of a
bigoted reaction by jurors was plausible. If that reaction had materialized, a wrongful acquittal
could have resulted. Thus, the prosecution had a significant stake which might have
countervailed over the probative value of the excluded defense evidence. The Olden Court's
decision to mandate the admission of the evidence reflects the value which even the members
of the Rehnquist Court attach to the accused's "fundamental" [FN197] right to present a
defense. As one court remarked, "[t]he states' interests in the evidentiary rules at issue in
Chambers and Washington were surely more significant than . . . purely procedural interest[s]"
[FN198] such as the consumption of time entailed in the presentation of rebuttal testimony by
defense experts. The countervailing probative dangers listed in Rule 403 are legitimate
considerations; but standing alone, they will rarely override the accused's interest in presenting
rebuttal testimony that satisfies the materiality and reliability prongs.
California v. Trombetta [FN199] is one of the Supreme Court's most famous criminal
law decisions in the past decade. Much has been written about the decision by commentators
[FN200] and other courts. [FN201] In these analyses, the commentators and courts have
conceived of Trombetta as exclusively a discovery decision. The evidentiary implications of
the decision, however, have been almost completely ignored. The purpose of this article has
been to highlight those implications. In Trombetta, the Court characterized the lost defense
evidence as speculative. The Court, however, failed to foresee that prosecutors would seize
upon the speculative character of defense rebuttal testimony as a basis for objecting to the
introduction of the testimony the Court assumed to be routinely admissible.
There are undoubtedly those who would argue that in Trombetta fact situations, the
fairest solution is to exclude the prosecution's scientific evidence whenever police conduct
prevents an independent retest of the physical evidence by defense experts. However, our
hypothesis is that the police acted in good faith, the initial test result was inculpatory, and the
exculpatory value of the lost defense evidence is highly conjectural. Under these facts, the
Trombetta Court is probably correct in concluding that the exclusion of highly relevant
scientific evidence is too Draconian.
The best analogy may be the dead man's or survivors' evidence acts. The early English
view was that parties were incompetent to testify. [FN202] At first, the American courts
adhered to that view. In the middle of the 19th century, however, there were sweeping
legislative reforms in most states. [FN203] The legislature generally abolished the
incompetency. However, "a compromise was forced upon the reformers" [FN204] -- the dead
man's acts. The acts provided that if one party to a transaction such as the formation of a
contract was dead at the time of trial, the other party was incompetent to testify against the
decedent's estate about the transaction. The argument ran that since death had silenced one
party, in fairness the law should silence the other. [FN205]
In time, most students of the law of evidence came to share Bentham's assessment that
the dead man's acts were "blind and brainless." [FN206] From a systemic perspective,
Bentham was certainly correct. The death of one party deprived the trier of fact of one of the
most important sources of information *87 about the transaction. The dead man's acts
aggravated the problem by preventing the jury from hearing from the other key source of
information, the surviving party. It would, however, be a mistake to entertain a naive faith in
the "curative" power of additional evidence: [FN207] Presenting a trier of fact with more and
more marginally relevant information does not necessarily improve the caliber of the final
decision. In some cases, deluging the trier with additional information may lower the quality of
the ultimate factual findings. But denying the trier the benefit of two of the potentially most
helpful sources of information will rarely advance the search for truth. On balance, the dead
man's acts were bad policy because they deprived the trier of fact of such valuable information.
Similarly, it would be unwise to exclude evidence of a highly relevant scientific analysis of
physical evidence, conducted by a police laboratory, to compensate for the defense's inability
to retest physical evidence which the police innocently disposed of or contaminated.
The optimum solution is the outcome proposed by this article: maintaining a fair,
adversarial balance in Trombetta cases by extending the accused's sixth amendment right to the
defense rebuttal evidence. When the rebuttal evidence passes muster under the materiality and
reliability prongs, the accused has a crucial interest in submitting that evidence to the trier of
fact. After Crane v. Kentucky, [FN208] it is clear that the accused's right attaches to testimony
which is logically relevant only to rebutting incriminating prosecution evidence. In striking the
balance under the sixth amendment test which the Court has announced, the judge admittedly
must consider the competing considerations underlying the evidentiary rules cited in the
prosecution's objection. However, those considerations should rarely be potent enough to
override the accused's stake. It is particularly inapt to invoke the expert testimony rules to bar
the admission of the defense evidence. Many of those rules are inspired by the courts' fear of
the risk that the trier of fact will overvalue scientific testimony. That risk is greatest precisely
when the judge admits the prosecution evidence but excludes the defense expert's rebuttal.
When the prosecutor objects to material, reliable defense testimony, the prosecutor is seeking
"the perpetuation of an unfair advantage." [FN209] In our adversary system of criminal
justice, [FN210] that type of advantage is both intolerable and unconstitutional.
FNa Professor of Law, University of California, at Davis, California; former chair,
Evidence Section, American Association of Law Schools.
FNaa Scofield & Volk, Sacramento, California. The authors would like to express their
appreciation to Mr. Joseph de Ulloa, Class of 1991, and Mr. David Kornbluh, Class of 1992,
University of California, at Davis Law School, who served as the authors' research assistants on
this project.
FN1. People v. Lepine, 215 Cal. App. 3d 91, 101, 263 Cal. Rptr. 543, 548 (1989).
FN2. 467 U.S. 479 (1984).
FN3. Id. at 482.
FN4. Id.
FN5. Id. at 485.
FN6. Id. at 489.
FN7. Id.
FN8. Id.
FN9. Id.
FN10. In Arizona v. Youngblood, 488 U.S. 51, 57 (1988), the Court commented on the
value of the lost evidence in Trombetta. The Court stated that "no more can be said than that
it could have been subjected to tests, the results of which might have exonerated the
defendant." Id. See also Note, Arizona v. Youngblood: Adherence to a Bad Faith Threshold
Test Before Recognizing a Deprivation of Due Process, 34 SO. DAK. L. REV. 407 (1989)
(noting that the in Trombetta and Youngblood, the Court emphasized the speculative
character of the lost evidence).
FN11. Trombetta, 467 U.S. at 490.
FN12. Id.
FN13. Id.
FN14. Id.
FN15. Id.
FN16. Id.
FN17. Id.
FN18. Id.
Sovereign Admissions: A Comment on United States v. Santos, 43 N.Y.U. L. REV. 108
(1968); Goldstein, The State and the Accused: Balance of Advantage in Criminal Procedure, 69
YALE L.J. 1149 (1960).
FN20. 488 U.S. 51.
FN21. For a general discussion of genetic marker tests, see P. GIANNELLI & E.
FN22. 488 U.S. at 55.
FN23. Id.
FN24. Id. at 56.
FN25. Id. The Court notes, however, that "here, unlike Trombetta, the State did not
attempt to make any use of the materials in its own case in chief." Id.
FN26. Id.
FN27. Id. at 59.
FN28. Lepine, 215 Cal. App. 3d at 101, 263 Cal. Rptr. at 548.
FN29. Id. at 96, 263 Cal. Rptr. at 545-46.
FN30. E.g., Barcott v. State, 741 P.2d 226, 228 (Alaska 1987).
FN31. Davis v. Commonwealth, 8 Va. App. 291, 293-94, 381 S.E.2d 11, 12 (1989).
FN32. Trombetta, 467 U.S. at 490.
FN33. Kurzman & Fullerton, Drug Identification, in SCIENTIFIC AND EXPERT
EVIDENCE 521, 554-56 (E. Imwinkelried 2d ed. 1981); Risinger, Denbeaux & Saks,
Exorcism of Ignorance as a Proxy for Rational Knowledge: The Lessons of Handwriting
Identification 'Expertise,' 137 U. PA. L. REV. 731, 770-71 (1989).
FN34. Lepine, 215 Cal. App. 3d at 94, 263 Cal. Rptr. at 544 (the prosecution objected
to the defense evidence as "irrelevant, speculative and potentially confusing").
FN35. Id. See also People v. Thompson, 215 Cal. App. 3d Supp. 7, 265 Cal. Rtpr. 105,
(Dept. Super. Ct. 1989).
FN36. FED. R. EVID. 401.
FN37. State v. Brayman, 110 Wash. 2d 183, 191, 205, 751 P.2d 294, 298, 305 (1988).
FN38. Imwinkelried, The Basic Legal Challenges to Per Se Statutes: Admissibility,
Sufficiency and Constitutionality, 1 D.W.I.J. 77, 90-93 (July/Aug. 1986).
FN39. Id. at 92.
FN40. Id.
FN41. Id. at 91-92.
FN42. Fuenning v. Super. Ct. in & for Cty. of Maricopa, 139 Ariz. 590, 596, 680
P.2d 121, 127 (1984) ("the defendant may attack the accuracy of the test on any relevant
ground, including inherent margin of error"); Burg v. Municipal Court, 35 Cal. 3d 257, 266
n.10, 673 P.2d 732, 737 n.10, 198 Cal. Rptr. 145, 149 n.10 (1983); Lepine, 215 Cal. App. 3d at
94, 100, 263 Cal. Rptr. at 544, 548-49; Thompson, 215 Cal. App. 3d Supp. at 13, 265 Cal. Rptr.
at 108 ("several states . . . allow general evidence refuting the accuracy and reliability of breath
test readings to go to the trier of fact"); People v. Cortes, 214 Cal. App. 3d Supp. 12, 18, 263
Cal. Rptr. 113, 115-16 (Dept. Super. Ct. 1989) ("Evidence of the range of individual
blood-breath ratios cannot be excluded"); People v. Brown, 143 Misc. 2d 270, 274-75, 540
N.Y.S.2d 650, 653 (Crim. Ct. 1989) ("The margin of error in the breathalyzer test should be
considered by the trier of fact in deciding whether the evidence sustains a finding of guilt
beyond a reasonable doubt."). See also Davis, 8 Va. App. 291, 381 S.E.2d 11.
FN43. See, e.g., People v. Herst, 197 Cal. App. 3d Supp. 1, 3, 243 Cal. Rptr. 83, 84
(Dept. Super. Ct. 1987) ("[g]eneral evidence of . . . a possibility of error in the partition ratio
will not suffice to rebut this presumption"); Lepine, 215 Cal. App. 3d at 95, 263 Cal. Rptr. at
545 ("Herst supports the proposition that general evidence concerning partition ratio
variability is irrelevant"); Cortes, 214 Cal. App. 3d Supp. at 16, 263 Cal. Rptr. at 114
(quoting Herst, 197 Cal. App. 3d. Supp. at 4 n.1, 243 Cal. Rptr. at 83, n.1, the court states that
"[t]he jury should not consider any conclusions made by any witness regarding the Defendant's
blood alcohol concentration based upon breath alcohol results which use a partition ratio other
than 2100 to 1"); State v. Lowther, 740 P.2d 1017, 1020 (Haw. Ct. App. 1987) (commenting on
City of Columbus, 24 Ohio App. 3d 173, 174, 493 N.E.2d 1002, 1003 (1985), the court stated
that the City of Columbus court in effect held that "the reliability of the Intoxilyzer has been
legislatively resolved and is not subject to attack by Defendant"); State v. Vega, 12 Ohio St. 3d
185, 188-89, 465 N.E.2d 1303, 1305, 1307 (1984) (the statute manifests a "legislative
determination" which renders "general [defense rebuttal] testimony" "nonrelevant"); City of
Columbus, 24 Ohio App. 3d at 174, 493 N.E.2d at 1003-04. Commenting on Vega, 12 Ohio
St. 3d 185, 465 N.E.2d 1303, the court declared that
[a]n accused may not use expert testimony to attack the general reliability of intoxilyzers as
valid, reliable breath-testing machines in view of the fact that the General Assembly has
legislatively provided for the admission of such tests. . . . [T]he efficiency of [the] testing
process is not subject to challenge, since it is presumed accurate. . . . [T]he trial court properly
excluded testimony which challenged the ability of intoxilyzers to accurately measure the
alcohol content of breath -- for example, quarreling with ratios between breath-alcohol content
and blood-alcohol content; the varying ability of persons to provide deep lung samples of
breath; the margin of error expected of intoxilyzers.
FN44. Davis, 8 Va. App. at 298, 381 S.E.2d at 15 (the Davis Court found that while the
use of the term "per se" suggests that blood alcohol level is conclusive proof it held that it is
not. The court called the evidence a fact which creates a rebuttable presumption that the
measurement reflects the blood alcohol concentration at the time of driving).
FN45. Vega, 12 Ohio St. 3d at 189, 465 N.E.2d at 1307.
FN46. Lepine, 215 Cal. App. 3d at 98, 263 Cal. Rptr. at 547.
FN47. Id. at 95, 263 Cal. Rptr. at 545.
FN48. See, e.g., State v. Downie, 117 N.J. 450, 468, 569 A.2d 242, 251 (1990); Romano
v. Kimmelman, 96 N.J. 66, 80, 474 A.2d 1, 9 (1984); People v. Donaldson, 36 A.D.2d 37, 40,
319 N.Y.S.2d 172, 176 (1971); State v. Johnson, 42 N.J. 146, 170-71, 199 A.2d 809, 822-23
(1964); State v. Manfredi, 577 A.2d 1338, 1339 (N.J. Super. 1990) (citing Downie, 117
N.J. 498, 569 A.2d 242); Brown, 143 Misc. 2d at 274, 540 N.Y.S.2d at 652; People v. Gower,
42 N.Y.2d 117, 121-22, 366 N.E.2d 69, 71, 397 N.Y.S.2d 368, 370 (Ct. App. 1977) (the court,
however, does not use the term of art, "judicial notice").
FN49. C. MCCORMICK, EVIDENCE § 332, at 931 (3d ed. 1984).
FN50. Downie, 117 N.J. at 468-69, 569 A.2d at 251; Brown, 143 Misc. 2d at 273, 540
N.Y.S.2d at 652 ("Our neighboring state of New Jersey . . . found that the new scientific
challenges to the breathalyzer regarding the variability of the 2100:1 breath-blood ratio were
inadmissible. . . . The court held that in light of Romano v. Kimmelman, 96 N.J. 66, 474 A.2d
1 (1984), which requires that judicial notice be given to breathalyzer test results in drunk
driving prosecutions, the new evidence could only be offered to make a record for a future
FN51. Youngblood, 488 U.S. at 56 (commenting on Trombetta, 467 U.S. 479); Note,
supra note 10.
FN52. See generally Giannelli, The Admissibility of Laboratory Reports in
Criminal Trials: The Reliability of Scientific Proof, 49 OHIO ST. L.J. 671 (1988).
FN53. See FED. R. EVID. 406.
FN54. Imwinkelried, The Constitutionality of Introducing Evaluative Laboratory
Reports Against Criminal Defendants, 30 HAST. L.J. 621, 644 (1979) [hereinafter The
Constitutionality of Introducing Evaluative Laboratory Reports Against Criminal Defendants].
FN55. P. GIANELLI & E. IMWINKELRIED, supra note 21, § 3-2, at 87.
FN56. There might appear to be a method of mooting the problem of unproven,
hypothetically assumed facts by cross-examining the prosecution witness. Some jurisdictions
take the position that if an expert testifies in response to a hypothetical question on direct
examination, the cross-examiner may vary the assumptions in the hypothesis even if there is no
evidence in the record to support a finding of the new assumption. C. MCCORMICK, supra
note 49, at 37 n.19; 4 F. BUSCH, LAW AND TACTICS IN JURY TRIALS 143 (1961). Some
states permit the cross-examiner to pose a hypothetical question even when the expert did not
testify in response to a hypothesis on direct. E. IMWINKELRIED, THE METHODS OF
ATTACKING SCIENTIFIC EVIDENCE § 11-2(B), at 375-76 (1982) [hereinafter THE
NOTEBOOK 173 (1981). The defense can argue that it is entitled to put hypothetical
questions to the prosecution's expert about the effect of possible errors on the test outcome
even if on direct examination the expert did not testify on the basis of hypothetically assumed
The accused, however, cannot be confident that the trial judge will accept this argument. The
judge might foreclose the use of a hypothetical question on cross-examination. Although some
jurisdictions permit the use of hypothetical questions on cross even when the expert did not
rely on a hypothesis during direct examination, that view is not universal. J. MCELHANEY,
supra, at 173. Even if the judge allows the use of a hypothetical question for the first time on
cross-examination, the judge might treat the formal cross-examination as a functional direct
examination. Thus, the cross-examiner is the questioner initially resorting to the hypothetical
question technique. Consequently, the judge might insist that as on direct examination, the
cross-examiner include assumptions in the hypothesis only if there is evidence in the record to
sustain a finding of the truth of the assumption.
CRIMINAL EVIDENCE]. See also Zaremski & Goldstein, Hypothetical Questions and
Discovery of Facts Underlying Opinion, in FORENSIC SCIENCES ch. 5 (1990).
FN58. COURTROOM CRIMINAL EVIDENCE, supra note 57, at § 1407.
FN59. Id. at § 1410.
FN60. Alabama Power Co. v. Robinson, 447 So. 2d 148, 152 (Ala. 1984); Edwards v.
California Sports, Inc., 206 Cal. App. 3d 1284, 1287, 254 Cal. Rptr. 170, 171 (1988); Hyatt v.
Sierra Boat Co., 79 Cal. App. 3d 325, 337- 38, 145 Cal. Rptr. 47, 54 (1978); People v. Sundlee,
70 Cal. App. 3d 477, 484, 138 Cal. Rptr. 834, 837 (1977); Clark v. Ross, 284 S.C. 543, 552-53,
328 S.E.2d 91, 97-98 (Ct. App. 1985); C. MCCORMICK, supra note 49, at § 14; 3 B.
WITKIN, CALIFORNIA EVIDENCE § 1849, at 1806 (3d ed. 1984).
FN61. C. MCCORMICK, supra note 49, § 14, at 37.
FN62. Clark, 284 S.C. at 552-53, 328 S.E.2d at 97-98.
FN63. E.g., Sundlee, 70 Cal. App. 3d at 484, 138 Cal. Rptr. at 837.
FN64. Some courts relax the requirement when factors beyond the proponent's control
preclude the proponent from gathering evidence to prove the truth of the assumed fact.
Vandermark v. Ford Motor Co., 61 Cal. 2d 256, 391 P.2d 168, 37 Cal. Rptr. 896 (1964), is
illustrative. In Vandermark, the plaintiff brought a personal injury action against an automobile
dealer and manufacturer. The plaintiff sustained injuries when he lost control of the car which
one defendant sold to him and which the other defendant manufactured. A key issue at trial
was the cause of the failure of the brake master cylinder piston to retract. Unfortunately, the
damage to the vehicle, caused by the accident, prevented the plaintiff's expert from definitively
determining whether the master cylinder assembly had been properly installed and adjusted
before the accident. Nevertheless, at trial the expert attempted to opine about the possible
causes of the failure. The trial judge struck the opinion as speculative. The appellate court held
that the trial judge erred. In so holding, the court stated:
[P]laintiffs were entitled to establish the existence of a defect and defendants' responsibility
therefor by circumstantial evidence, particularly when, as in this case, the damage to the car in
the collision precluded determination whether or not the master cylinder assembly had been
properly installed and adjusted before the accident.
Id. at 260, 391 P.2d at 170, 37 Cal. Rptr. at 898. See also People v. Guntert, 126 Cal. App. 3d
Supp. 1, 10, 179 Cal. Rptr. 426, 430 (Dept. Super. Ct. 1981) (the court should consider
"whether a party offering . . . evidence had had a reasonable opportunity to investigate
evidence of the condition at a prior time").
56, at § 6-6(C)
FN66. Id. § 6-6(C), at 221.
FN67. See FED. R. EVID. 702-04.
THE STUDY OF EVIDENCE 444 (2d ed. 1986) [hereinafter MATERIALS FOR THE
FN69. See, e.g., Mayhew v. Bell S.S. Co., 917 F.2d 961 (6th Cir. 1990). See also Joseph,
Less Than Certain Medical Testimony, 14 TRIAL 51 (Jan. 1978).
FN70. Brown v. Parker-Hannifin Corp., 919 F.2d 308, 311-12 (5th Cir. 1990); Lanza v.
Poretti, 537 F. Supp. 777 (E.D. Pa. 1982); Vuocolo v. Diamond Shamrock Chemicals Co., 240
N.J. Super. 289, 573 A.2d 196 (1990); Becker v. Lake County Memorial Hosp. West, 53
Ohio St. 3d 202, 560 N.E.2d 165 (1990); Collins by Collins v. Straka, 164 Ill. App. 3d 355, 361,
517 N.E.2d 1147, 1151 (1987); Garza v. Keillor, 623 S.W.2d 669, 672 (Tex. Ct. App. 1981).
FN71. E.g., United States v. Bowers, 660 F.2d 527, 529 (5th Cir. 1981); State v. Clark,
324 N.C. 146, 159, 377 S.E.2d 54, 62-63 (1989); People v. Babbitt, 45 Cal. 3d 660, 684-86, 755
P.2d 253, 264-66, 248 Cal. Rptr. 69, 80-81 (1988); Welch v. State, 677 S.W.2d 562 (Tex. Ct.
App. 1984).
FN72. E.g., Lohrmann v. Pittsburgh Corning Corp., 782 F.2d 1156, 1160 (4th Cir.
FN73. FED. R. EVID. 403.
FN74. E.g., Brown v. Parker-Hannifin Corp., 919 F.2d 308, 311-312 (5th Cir. 1990);
Nelson v. Trinity Medical Center, 419 N.W.2d 886, 892 (N.D. 1988).
FN75. FED. R. EVID. 702.
FN76. COURTROOM CRIMINAL EVIDENCE, supra note 57, at §§ 131-33.
FN77. In explaining its decision to exclude evidence attacking the general reliability of
the breathalyzer, the Ohio Supreme Court agreed with the dissent in the court below which
characterized the evidence as "speculative." Vega, 12 Ohio St. 3d at 186, 465 N.E.2d at 1305.
Similarly, in Lepine, 215 Cal. App. 3d at 94-95, 263 Cal. Rptr. at 544-45, the trial judge
sustained a prosecutor's objection that defense rebuttal evidence was "speculative."
FN78. MATERIALS FOR THE STUDY OF EVIDENCE, supra note 68, at Ch. 16.
FN79. FED. R. EVID. 403.
FN80. Imwinkelried, The Meaning of Probative Value and Prejudice in Federal Rule of
Evidence 403: Can Rule 403 Be Used to Resurrect the Common Law of Evidence?, 41
VAND. L. REV. 879, 884-85 (1988).
PROCEDURE: EVIDENCE § 5213, at 259-60 (1978).
FN82. Id. § 5214, at 271; Imwinkelried, supra note 80, at 885.
FN83. Johnson, 42 N.J. at 171, 199 A.2d at 823.
FN84. Downie, 117 N.J. at 453, 569 A.2d at 243 (citing Johnson, 42 N.J. at 171, 199
A.2d at 823).
FN85. MATERIALS FOR THE STUDY OF EVIDENCE, supra note 68, at 262.
FN86. FED. R. EVID. 403.
FN87. Id.
FN88. E.g., Lepine, 215 Cal. App. 3d at 94-95, 263 Cal. Rptr. at 544-45.
FN89. Brayman, 110 Wash. 2d at 205, 751 P.2d at 305.
FN90. Id.
FN91. Id. See also State v. Manfredi, 242 N.J. Super. 708, 710, 577 A.2d 1338, 1339
(1990) ("long trials complicated" by expert testimony).
FN92. Myers, The Battle of the Experts: A New Approach to an Old Problem in
Medical Testimony, 44 NEB. L. REV. 539 (1965).
FN93. People v. Reilly, 196 Cal. App. 3d 1127, 242 Cal. Rptr. 496 (1987).
FN94. Id. at 1135, 242 Cal. Rptr. at 501.
FN95. State v. Aquilera, 25 Crim. L. Rep. (BNA) 2189 (Fla. County Ct., May 7, 1979).
FN96. 144 Misc. 2d 956, 957, 545 N.Y.S.2d 985, 986 (Supp. 1989).
FN97. United States v. Barron, 707 F.2d 125 (5th Cir. 1983).
FN98. Doty v. Sewall, 908 F.2d 1053, 1058 (1st Cir. 1990) (citing 1 S. CHILDRESS &
FN99. Comment, Evidence -- Other Crime -- Balancing Relevance and Need Against
Unfair Prejudice to Determine the Admissibility of Other Unexplained Deaths as Proof of the
Corpus Delicti and the Perpetrator's Identity, 6 RUT.-CAM. L.J. 173, 177 (1974).
FN100. Teitelbaum & Hertz, Evidence II: Evidence of Other Crimes as Proof of
Intent, 13 N.M.L. REV. 423, 433 (1983).
FN101. Hall, The Trial of a Recidivist and Proof of Other Crimes, CASE &
COMMENT 47-48 (Sept.-Oct. 1979).
FN102. Doty, 908 F.2d at 1058; United States v. Simpson, 910 F.2d 154, 157 (4th Cir.
1990); Barron, 707 F.2d 125.
FN103. E.g., Vega, 12 Ohio St. 3d at 186, 465 N.E.2d at 1305 ("an accused is not
denied his constitutional right to present a defense" by the exclusion of evidence attacking the
general reliability of the breath-testing instrument).
FN104. E.g., People v. Mertz, 68 N.Y.2d 136, 146, 497 N.E.2d 657, 662, 506 N.Y.S.2d
290, 295 (1986) ("To foreclose a defendant's introduction of evidence seeking to establish that
his BAC while operating was less than .10 may raise doubt as to constitutionality. . . . ").
FN105. E.g., Vega, 12 Ohio St. 3d at 190, 465 N.E.2d at 1308 (1984) (Brown, J.,
dissenting) (the accused has a "constitutional right to present all relevant evidence in his
defense to the crime with which he is charged").
FN106. E.g., Champion v. Dept. of Public Safety, 721 P.2d 131 (Alaska 1986) (This
case involved the failure of the state to preserve a breath sample rather than excluding defense
rebuttal evidence. The court held that the failure denied the motorist a fair hearing and thus
violated due process).
FN107. See, e.g., Barcott v. Dept. of Public Safety, 741 P.2d 226, 228-29 (Alaska 1987)
("due process requires consideration of the margin of error inherent in the breath testing
procedure used in this case; . . . the defendant has a constitutionally guaranteed right to attack
the accuracy of a breath alcohol test"); Thompson, 215 Cal. App. 3d Supp. at 14, 265 Cal. Rptr.
at 109 ("the exclusion of the general evidence denied appellant a fair trial"); Lowther, 740 P.2d
at 1019, 1021 ("the trial court unconstitutionally excluded relevant expert testimony . . .
proferred by Defendant").
FN108. Trombetta, 467 U.S. at 490.
FN109. Lowther, 740 P.2d at 1019.
FN110. Thompson, 215 Cal. App. 3d 14, 265 Cal. Rptr. at 109.
FN111. Barcott, 741 P.2d at 228; Lowther, 740 P.2d at 1019.
FN113. 388 U.S. 14 (1967).
FN114. Id. at 23.
FN115. Imwinkelried, Chambers v. Mississippi, __U.S.__ (1973): The Constitutional
Right to Present Defense Evidence, 62 MIL. L. REV. 225, 240 (1973).
FN116. E.g., People v. Scott, 52 Ill. 2d 432, 288 N.E.2d 478 (1972), cert. denied, 410
U.S. 941 (1973).
FN117. Id. at 439, 288 N.E.2d at 482.
FN118. 410 U.S. 284 (1973).
FN119. The trial judge also denied Chambers permission to treat McDonald as a
hostile witness and use leading questions to interrogate him at trial. Chambers argued that the
denial of permission violated his sixth amendment confrontation right. The Supreme Court
accepted Chambers' argument. Id. at 295-98.
FN120. Id. at 302.
FN121. Id. at 300.
FN122. Id. at 302.
FN123. See EXCULPATORY EVIDENCE, supra note 112.
FN124. Id. at § 10-5.a.
FN125. Id. at §§ 10-5.c-d.
FN126. Id. at § 9-4.
FN127. Id. at ch. 8.
FN128. Lowther, 740 P.2d at 1021 (quoting the dissent in Vega, 12 Ohio St. 3d 185,
465 N.E.2d 1303).
FN129. EXCULPATORY EVIDENCE, supra note 112, § 2-4.a, at 49-50.
FN130. Id. § 2-4.b, at 50-55.
FN131. Id. § 2-4.a, at 41-47.
FN132. Peterson, Ryan, Houlden & Mihajlovic, The Uses and Effects of Forensic
Science in the Adjudication of Felony Cases, 32 J. FORENSIC SCI. 1730, 1749- 50 (1987).
FN133. United States v. Fatico, 458 F. Supp. 388, 405-06 (E.D.N.Y. 1978).
FN134. See generally Giannelli, supra note 52.
FN135. Risinger, Denbeaux & Saks, supra note 33, at 738-51.
FN136. Id.
FN137. Id.
FN138. Miike & Hewitt, Accuracy and Reliability of Urine Drug Tests, 36 KAN. L.
REV. 641, 651-57 (1988).
FN139. Hansen, Caudill & Boone, Crisis in Drug Testing: Results of CDC Blind Study,
253 J. A.M.A. 2382 (1985).
FN140. In re Winship, 397 U.S. 358, 361 (1970).
FN141. EXCULPATORY EVIDENCE, supra note 112, § 2-4.a, at 41-47.
FN142. Id. § 2-4.a, at 42-44.
FN143. Westen, The Compulsory Process Clause, 73 MICH. L. REV. 71, 155 (1974).
FN144. Id.
FN145. Id.
FN146. EXCULPATORY EVIDENCE, supra note 112, § 2-4.a, at 44-47; Haddad,
The Future of Confrontation Clause Developments: What Will Emerge When the Supreme
Court Synthesizes the Diverse Lines of Confrontation Decisions?, 81 J. CRIM. L. &
CRIMINOLOGY 77, 78, 83 (1990); The Constitutionality of Introducing Evaluative
Laboratory Reports Against Criminal Defendants, supra note 53, at 629-35.
FN147. E.g., Barcott, 741 P.2d at 228-29.
FN148. People v. Collins, 94 Misc. 2d 704, 710, 405 N.Y.S.2d 365, 369 (Sup. Ct. 1978)
(excluding sound spectrography evidence because of the "preliminary and incomplete
experimentation" with the underlying premises of the technique); State v. Smith, 50 Ohio App.
2d 183, 192, 362 N.E.2d 1239, 1245-46 (1976) (excluding testimony about a modification of
the Harrison-Gilroy gunshot residue test because no one, "including [the witness], has ever
conducted any experiments to attempt to objectively determine" the accuracy of the modified
4-4(B), at 123-24.
FN149. United States v. Bifield, 702 F.2d 342, 350 (2d Cir.), cert. denied, 461 U.S. 931
(1983); Hughes v. Matthews, 576 F.2d 1250, 1258 (7th Cir.), cert. denied, 439 U.S. 801 (1978).
FN150. EXCULPATORY EVIDENCE, supra note 112, at § 2-3.
FN151. Id.
FN152. Westen, supra note 143, at 107. See also Westen, Confrontation and
Compulsory Process: A Unified Theory of Evidence for Criminal Cases, 91 HARV. L. REV.
567, 592 (1978).
FN153. Clinton, The Right to Present a Defense: An Emergent Constitutional
Guarantee in Criminal Trials, 9 IND. L. REV. 711, 756 (1976).
FN154. Note, Defendant v. Witness: Measuring Confrontation and Compulsory
Process Against Statutory Communications Privileges, 30 STAN. L. REV. 935, 990 (1978).
FN155. Commonwealth v. Drew, 397 Mass. 65, 75 n.10, 489 N.E.2d 1233, 1241 n.10
FN156. Imwinkelried, The Case for Recognizing a New Constitutional Entitlement:
The Right to Present Favorable Evidence in Civil Cases, 1990 UTAH L. REV. 1, 5 (citing
Rock v. Arkansas, 483 U.S. 44, 57 (1987) and Chambers v. Mississippi, 410 U.S. 284, 299
(1973)). In Rock, the Court held that an accused had the right to testify about facts
remembered only after hypnotic induction. At the time of the Rock decision, it may have been
the prevailing view in the United States that hypnotically enhanced testimony was per se
inadmissible. In Chambers, the Court ruled that the accused had the right to introduce a third
party's declaration against penal interest over a prosecution hearsay objection. In the opinion,
the majority conceded that the "materialistic limitation on the declaration-against-interest
hearsay exception [restricting the exception to statements against proprietary and pecuniary
interest] appears to be accepted by most States in their criminal trial processes." Chambers, 410
U.S. at 299.
FN157. Note, Hypnosis and the Right to Testify: An Evidentiary and Constitutional
Dilemma for Connecticut, 9 BRIDGEPORT L. REV. 359, 409 (1988).
FN158. Chipman v. Mercer, 628 F.2d 528, 531 (9th Cir. 1980).
FN159. See generally Allen, Structuring Jury Decisionmaking in Criminal Cases: A
Unified Constitutional Approach to Evidentiary Devices, 94 HARV. L. REV. 321, 342-48
FN160. Brayman, 110 Wash. 2d 183, 751 P.2d 294.
FN161. State v. Ulrich, 478 N.E.2d 812, 821, 824 (Ohio Ct. App. 1984).
FN162. FED. R. EVID. 201(g).
NO. 650, 93d Cong., 1st Sess. 6 (1973).
FN164. Barcott, 741 P.2d at 230 ("due process will not allow the results of a chemical
test . . . to be conclusively presumed accurate"); Lowther, 740 P.2d at 1020 ("'[T]he Legislature
may not declare the weight to be given to evidence or what evidence shall be conclusive proof
of an issue of fact"').
FN165. 476 U.S. 683 (1986).
FN166. Id. at 687.
FN167. Id. at 690.
FN168. Id. at 691.
FN169. Id.
FN170. In a number of other cases, the Supreme Court exercised the power to
independently assess the logical relevance of evidence. EXCULPATORY EVIDENCE, supra
note 112, § 5-2b, at 118-21. On occasion such as in Tot v. United States, 319 U.S. 463 (1943),
the Court disagreed with a legislative determination of relevance.
FN171. See, e.g., State v. Dorsey, 87 N.M. 323, 532 P.2d 912 (Ct. App.), aff'd on other
grounds, 88 N.M. 184, 539 P.2d 204 (1975); State v. Sims, 52 Ohio Misc. 31, 369 N.E.2d 24
(1977); P. GIANNELLI & E. IMWINKELRIED, supra note 21, at § 8-3(D).
FN172. See, e.g., Parisie v. Greer, 671 F.2d 1011 (7th Cir. 1982), vacated, 705 F.2d 882
(7th Cir. 1983), cert. denied, 464 U.S. 918 (1983); Hughes v. Matthews, 576 F.2d 1250 (7th Cir.
1978); Hendershott v. People, 653 P.2d 385 (Colo. 1982), cert. denied, 459 U.S. 1225 (1983).
FN173. 483 U.S. 44.
FN174. Rock v. State, 288 Ark. 566, 573, 708 S.W.2d 78, 81 (1986), vacated, 483 U.S.
44 (1987).
FN175. Casenote, The Admissibility of Hypnotically Refreshed Testimony: Rock v.
Arkansas, 30 B.C.L. REV. 573, 594 (1989).
FN176. Rock, 483 U.S. at 55.
FN177. Id. at 52.
FN178. Id.
FN179. Id. at 59.
FN180. Id. at 61.
FN181. See, e.g,. Note, Rock v. Arkansas: Hypnotically "Refreshed" Testimony or
Hypnotically "Manufactured" Testimony?, 74 CORNELL L. REV. 136 (1988). See also
Casenote, supra note 175, at 594-98 (generally discussing the extension of the accused's
constitutional right by the Rock Court).
FN182. Patrick v. State, 295 Ark. 473, 478, 750 S.W.2d 391, 393 (1988).
FN183. Reed, Practical Pitfalls in Handling Scientific Evidence, in SCIENTIFIC AND
FN184. People v. Collins, 68 Cal. 2d 319, 320, 438 P.2d 33, 33, 66 Cal. Rptr. 497, 497
FN185. People v. Kelly, 17 Cal. 3d 24, 32, 549 P.2d 1240, 1245, 130 Cal. Rptr. 144, 146
(1976) (quoting Huntingdon v. Crowley, 64 Cal. 2d 647, 656, 414 P.2d 382, 390, 51 Cal. Rptr.
254, 262 (1966)).
FN186. United States v. Addison, 498 F.2d 741, 744 (D.C. Cir. 1974).
FN187. Reed v. State, 283 Md. 374, 385, 391 A.2d 364, 370 (1978).
FN188. MATERIALS FOR THE STUDY OF EVIDENCE, supra note 68, at 444.
FN189. Imwinkelried, The Standard for Admitting Scientific Evidence: A Critique
from the Perspective of Juror Psychology, 28 VILL. L. REV. 554, 562-63 (1983).
FN190. See generally EXCULPATORY EVIDENCE, supra note 112, at ch. 7.
FN191. 488 U.S. 227 (1988).
FN192. Id. at 230.
FN193. Id at 231. See also Wealot v. Armontrout, 740 F. Supp. 1436 (W.D. Mo. 1990).
FN194. The advisory committee to Federal Rule 403 states that "[u]nfair prejudice'
within [this] context means an undue tendency to suggest a decision on an improper basis. . . .
" FED. R. EVID. 403 advisory committee's note.
FN195. Olden, 488 U.S. at 233.
FN196. Id. at 232.
FN197. Chambers, 410 U.S. at 302.
FN198. United States ex rel. Veal v. Wolff, 529 F. Supp. 713, 722 (N.D. Ill. 1981), rev'd
on other grounds, 693 F.2d 642 (7th Cir. 1982).
FN199. 467 U.S. 479; Annotation, Prosecution's Failure to Preserve Potentially
Exculpatory Evidence as Violating Criminal Defendant's Due Process Rights Under Federal
Constitution -- Supreme Court Cases, 102 L. Ed.2d 1041 (1990).
FN200. E.g., Reidinger, Good Faith, Bad Evidence, 75 A.B.A. J. 48 (Feb. 1989); Note,
supra note 10.
FN201. E.g., State v. Matafeo, 71 Haw. 183, 787 P.2d 671 (1990); People v. Sheppard,
701 P.2d 49 (Colo. 1985); State v. Leroux, 18 Conn. App. 223, 557 A.2d 1271 (1989);
Annotation, Consumption or Destruction of Physical Evidence Due to Testing or Analysis By
Prosecution's Expert as Warranting Suppression of Evidence or Dismissal of Case Against
Accused in State Court, 40 A.L.R.4th 594 (1985).
FN202. C. MCCORMICK, supra note 49, § 65, at 159.
FN203. Id.
FN204. Id.
FN205. Id.
FN206. Id. § 65, at 160.
FN207. Graham, "There'll Always Be An England:" The Instrumental Ideology of
Evidence, 85 MICH. L. REV. 1204, 1211 (1987).
FN208. 476 U.S. 683.
FN209. Lepine, 215 Cal. App. 3d at 101, 263 Cal. Rptr. at 548.
FN210. S. LANDSMAN, supra note 19.