Expert testimony at Virginia DUI and criminal trials has its limits for both the defense and prosecution

Expert testimony is involved in many of my Virginia DUI and criminal trials. As a Fairfax DWI lawyer, I further address in this article some of the key aspects of the law governing experts in Virginia criminal trials, including when the defense calls a forensic toxicologist to testify about such items as GERD / acid reflux, margins of uncertainty with breath and blood testing for alcohol and drugs, and other aspects of DUI cases.

What hurdles must be cleared to present expert testimony in Virginia DUI and criminal trials?

Expert testimony is permitted in Virginia DUI and criminal cases when the expert, as follows, is qualified beyond the following first sentence, as detailed in the following text: “In a civil proceeding, if scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education may testify thereto in the form of an opinion or otherwise… In a criminal proceeding, expert evidence is admissible if the standards set forth in subdivision (a)(i) of this Rule are met and, in addition, the court finds that the subject matter is beyond the knowledge and experience of ordinary persons, such that the jury needs expert opinion in order to comprehend the subject matter, form an intelligent opinion, and draw its conclusions.” Virginia Supreme Court (Va. S. Ct.) Rule 2:702.

May expert witnesses in Virginia DUI or criminal trials rely on the diagnoses and conclusions of other experts?

Often expert testimony relies on the mixed fact-expert conclusion of another expert. This can for instance arise when a Virginia DUI defendant raises a GERD / acid reflux defense, and the where the defendant’s GERD was diagnosed by a physician who does not testify at trial. I tell my clients in advance not to automatically expect that a non-physician testifying forensic toxicologist will be permitted to state whether the defendant has GERD, let alone whether s/he had GERD at the time the defendant submitted to breath testing in the DUI case. The following caselaw quote — particularly the last sentence — is important to know for this and all other Virginia and criminal defense work:

“The issue whether a witness is qualified to render [expert testimony]  is a question submitted to the sound discretion of the trial court. Poliquin v. Daniels, 254 Va. 51, 57, 486 S.E.2d 530, 534 (1997); King v. Sowers, 252 Va. 71, 78, 471 S.E.2d 481, 485 (1996); Tazewell Oil Co. v. United Va. Bank, 243 Va. 94, 110, 413 S.E.2d 611, 620 (1992). The record must show that the proffered expert witness has sufficient knowledge, skill, or experience to render him competent to testify as an expert on the subject matter of the inquiry. King, 252 Va. at 78, 471 S.E.2d at 485; Griffett v. Ryan, 247 Va. 465, 469, 443 S.E.2d 149, 152 (1994); Noll v. Rahal, 219 Va. 795, 800, 250 S.E.2d 741, 744 (1979). The fact that a witness is an expert in one field does not make him an expert in another field, even though the two fields are closely related. Tazewell Oil Co., 243 Va. at 110, 413 S.E.2d at 620; VEPCO v. Lado, 220 Va. 997, 1005, 266 S.E.2d 431, 436 (1980).” Combs v. Norfolk & Western Railway Co., 256 Va. 490, 497 (1998).

Should my Virginia DUI or criminal defense lawyer present expert testimony at my trial?

Talk to your Virginia DUI or criminal defense lawyer whether you should arrange for expert testimony your trial. If your lawyer recommends an expert witness — if within your litigation budget — the right expert needs to be identified and obtained, and that person’s testimony needs to be well prepared.

Virginia DUI lawyer Jonathan Katz has successfully defended hundreds of people charged with driving under the influence of alcohol, drugs and both. Learn the major defensive difference that Jon Katz can make in your case through calling 703-383-1100 to schedule a free in-person confidential consultation with Jon about your court-pending case.