California DMV Manual witness examination language is published in this new Article by The San Diego County DUI Law Center. This section deals with examples of language designed to attack the driver's expert and to put in a written decision to suspend:
"Expert Witness Credibility
The hearing officer should watch for signs of partiality in the expert’s testimony related to their credibility as a witness. Impartiality is not always present in expert testimony.
When it is not evident, the testimony may be suspect to credibility considerations. (See Section 12.173 Resolving Credibility) It may occur that the testimony is credible, but incomplete during cross-examination. The hearing officer needs to ask questions that may have gone unanswered during the prior examination. Ask questions to elicit a description of any possible “untold” facts.
• Ask questions that may reveal whether the expert's knowledge of the driver's
drinking pattern and BAC calculations are based upon hearsay.
• Distinguish if the expert's testimony presented as fact is actually speculation as to what may have occurred during the chemical testing.
• Fully explore any tendency of the expert to advocate the attorney's case and note this for the record. You may use this in a finding of fact in your report as a basis of dismissing the expert's testimony, but it must be a matter of record, and not from your personal knowledge.