In California, it is important to not be considered a "Refusal" in a DUI case as your license can be suspended for a very long time (with no restriction) and mandatory jail is required if convicted.
So if you have trouble blowing or can't provide a good enough breath sample upon being arrested for drunk driving in California, here's what you need to know:
The Vehicle code states that if one is "incapable" of completing a test then he must submit to the other available test. VC §23612(a)(2)(A):
If the person is lawfully arrested for driving under the
influence of an alcoholic beverage, the person has the choice of
whether the test shall be of his or her blood or breath and the
officer shall advise the person that he or she has that choice. If
the person arrested either is incapable, or states that he or she is
incapable, of completing the chosen test, the person shall submit to
the remaining test. If a blood or breath test, or both, are
unavailable, then paragraph (2) of subdivision (d) applies.
Also see People v. Gary Allen Sugarman, (2002) 96 Cal. App.4th 210,
Butler v. Department of Motor Vehicles, (1981) 115 Cal.App.3d 913,
Buchanan v. Department of Motor Vehicles (1979) 100 Cal.App.3d 293, and
McConville v. Alexis, (1979) 97 Cal.App.3d 593.
What if the California DUI investigating officer thinks I may be "on drugs?"
California law states what is required for the blood test in addition to a breath test is VC 23612(a)(2)(C):
A person who chooses to submit to a breath test may also be
requested to submit to a blood or urine test if the officer has
reasonable cause to believe that the person was driving under the
influence of a drug or the combined influence of an alcoholic
beverage and a drug and if the officer has a clear indication that a
blood or urine test will reveal evidence of the person being under
the influence. The officer shall state in his or her report the facts
upon which that belief and that clear indication are based.