Experts and hearsay- Fairfax criminal defense lawyer addresses their boundaries

Experts [EWs] in criminal trials are limited by the following Virginia rule of evidence: “In criminal cases, the opinion of an expert is generally admissible if it is based upon facts personally known or observed by the expert, or based upon facts in evidence.” Virginia Evidence Rule 2:703(b)(opens in new tab). As a Fairfax criminal defense lawyer, I want the expert witnesses (EWs) hired by my side to be able to testify on as wide a range of otherwise beneficial hearsay evidence as possible and want to hem in the hearsay that prosecution EWs may reference. A recent unpublished Virginia Court of Appeals opinion says that “we have held that [EWs] do not violate the [Virginia Supreme Court’s] Simpson rule when they rely on (1) standardized data used as a tool by the expert and without which the expert could not form an opinion or (2) qualitative information gathered through observations unrelated to the specific facts of a case…” Bahoujabour v. Commonwealth of Virginia, Record No. 2147-24-4 (Va. App. 2026) (unpublished). What is the Simpson rule? In “criminal proceedings, expert witnesses may not ‘base [their] opinion on facts not in evidence.’ Simpson v. Commonwealth, 227 Va. 557, 565 (1984).” Bahoujabour. 

Does Virginia evidentiary law allow prosecutors to present the testimony of experts in drug trafficking, gang activity and behavior of sexual trauma victims?

Applying the foregoing approach with trial experts, Bahoujabour affirms the defendant’s convictions for rape and domestic assault and battery, rejecting Bahoujabour‘s arguments that the trial court’s allowing a domestic violence and trauma expert to testify that sexual trauma “survivors may ‘cry[], scream[], yell[],’ laugh ‘eerie[ly],’ ‘shut[] down,’ ‘mov[e] really quickly,’ lose focus, or become distracted easily.” The expert also testified that: “Based on published research regarding her own client observations, [Commonwealth’s Attorney’s expert witness] Stockenstroom testified that victims commonly report remaining in an abusive relationship due to pressure created by physical, psychological, emotional, and financial abuse cycles. She also opined that domestic violence or sexual abuse violence survivors may delay reporting their experiences for fear of retribution, embarrassment, or safety.” Bahoujabour. In that regard, Bahoujabour says that the Virginia Court of Appeals’ decision in Kern v. Commonwealth of Virginia, 2 Va. App. 84 (1986) and Funderburk v. Commonwealth of Virginia, 6 Va. App. 334 (1988) “recognize that an expert’s opinion is often rendered in the form of an analytical conclusion derived from data collected in their field—put simply, ‘information and knowledge . . . within the expertise of the [expert].’… Framed this way, the data undergirding the expert’s analytical conclusions is not ‘fact’ offered for adjudication by the fact finder; it merely enables the expert to render their testimony in the first place.” Bahoujabour (citation omitted.) As an unpublished appellate opinion, Bahoujabour is not binding on any trial nor appellate judge, but does rely upon binding appellate opinions, and as a Fairfax criminal defense lawyer, I have heard at least two Virginia trial judges state their giving general reliance even on unpublished Virginia appellate opinions. Nonetheless, the foregoing caselaw is likely to be used by trial judges to continue to permit the junk science testimony of so-called narcotics EWs, gang EWs and various other crime EWs presented by prosecutors.

What’s good for the goose is good for the gander

At the same time, the foregoing legal principles must be permitted by trial judges to apply also to experts for criminal defendants. Virginia judges are generalists, so your Virginia criminal defense attorney should be ready not only with the relevant court opinions to show the judge (with a copy to the assistant commonwealth’s attorney / prosecutor), but also with appropriate legal memoranda filed before trial, and appropriate pretrial discussion, as appropriate. In case your trial judge nonetheless will bar certain data to be reference by your expert witness,  your Virginia criminal defense attorney needs to consider whether s/he will simply get that data into evidence after all, whether, for instance, by testimony, records custodians, or the business records rule in Virginia Code § 8.01-390.3(B). Furthermore, I am ready to argue that if a court is going to accept into evidence a breath certificate of analysis in a Virginia DUI prosecution under Virginia Code § 18.2-266, Due Process (under the federal Constitution’s Fifth and Fourteenth Amendments) and principles of self authentication should permit the defense expert to testify about the underlying data obtained by subpoena by the defense from the Virginia Department of Forensic Science. 

What should my Virginia criminal defense lawyer do if my trial judge bars my expert witness from addressing a particular set of data?

Your Virginia criminal defense lawyer needs have and act on a mental and/or written flowchart for handling any realistically possible trial contingency, whether that be the barring of certain testimony from your experts or otherwise. Before you hire a criminal defense attorney, talk with them about how they will handle this and other material trial risks.

Fairfax criminal defense lawyer Jonathan Katz approaches your defense as an integrated holistic whole, going to court with a full toolkit, knowing how to use each of those tools, and knowing only to use the tools needed at the right time and in the right way against Virginia felony, misdemeanor and DUI prosecutions. For your free in-person initial confidential consultation with Fairfax criminal lawyer Jon Katz about your court-pending prosecution, call us for an appointment, at 703-383-1100, Info@KatzJustice.com or (text) 571-406-7268.