Defense counsel generally should match expert for expert with the prosecution by locating and preparing defense experts including breath test operators and supervisors, physicians, forensic chemists, toxicologists, and, when relevant, accident reconstruction engineers. Physicians, nurses, medical technicians, chemists and accident reconstruction engineers are relatively easy to find. A qualified expert on breath tests who is not already employed by or retained by the state, on the other hand, is much more difficult to find.
In a prosecution for gross vehicular manslaughter while intoxicated, driving while under the influence of alcohol or drugs and causing injury, driving with a blood-alcohol level of 0.10 percent or greater and causing injury, and being under the influence of a controlled substance (cocaine), the trial court did not err in permitting the People's expert, the chief forensic toxicologist at a county crime laboratory, to testify regarding the combined effects of alcohol and cocaine. Given the paucity of studies on the subject, it was quite proper to allow the expert to draw an inference based on her extensive knowledge of physiology, pharmacology, depressants and stimulants and, specifically, alcohol and cocaine. Work in a particular field is not an absolute prerequisite to qualification as an expert in that field. With the understanding that the expert had neither been trained in nor conducted studies on the combined effects, and that her opinion was based upon inference, the jury could properly weigh her testimony that cocaine would not counteract the noxious effects of alcohol against defendant's contrary testimony. People v. Coyle (1994, 6th Dist) 22 Cal App 4th 1679, 28 Cal Rptr 2d 488, 94 CDOS 1628, 94 Daily Journal DAR 2821, review gr (Cal) 31 Cal Rptr 2d 125, 874 P2d 900, 94 CDOS 4054, 94 Daily Journal DAR 7523 and reprinted for tracking pending review (6th Dist) 28 Cal App 4th 66.
Opinion on field sobriety test false positives: Erroneous statistical data elicited by defendant from expert on field sobriety tests regarding alleged percentage of sober persons who fail field sobriety tests opened door for State on cross-examination to point out error that manual from which statistical evidence was drawn did not use terms "sober" or "intoxicated" but instead provided statistics for persons with blood alcohol content of .10 or more who failed tests. Schmidt v. State, 816 N.E.2d 925 (Ind. Ct. App. 2004), transfer denied, 831 N.E.2d 743 (Ind. 2005).
In prosecution for DUI, third offense, trial court abused its discretion in denying defendant's motion for appointment and payment of expert witness to challenge reliability of Breathalyzer tests where issue of reasonableness of time between arrest and administering of test was particularly important in case, and thus defendant could not have safely proceeded to trial without appointment of expert to testify about reliability of tests following delay between time of arrest and administering of tests. People v. Jacobsen (1994) 205 Mich App 302, 517 NW2d 323.
Selecting and preparing expert witnesses—Breath-test expert
Since the defense attorney cannot expect the state's chemist to bring out or embrace the literature that is unfavorable to breath tests, locating an expert breath-test witness for the defense can make the difference between "guilty" and "not guilty" verdicts in many cases. Ideally, such an expert holds advanced degrees in chemistry, has attended schools on the operation of breath-testing devices, is familiar with the literature on the subject, and personally participated in experiments. The best places to search for such an expert are in college chemistry departments, professional societies, and independent testing laboratories. However, in many areas it is impossible to find a breath test expert to testify for the defense because there are none. About the only way to cope with such a situation is to locate a qualified chemist and persuade him to study information on the breath-test device. If qualified by intense recent study of the literature and experience with the particular testing device, any chemist would be qualified concerning the accuracy of the test, and could give an opinion regarding the defendant's intoxication based on the blood-alcohol content shown by the police-administered test.
Although experts in DUI case can be expensive and labor intensive, they are generally worth the effort if feasible. Experts are seldom utilized unless serious bodily injury or death are present; however if possible, experts should be used more frequently.