using cross examination to uncover expert witness bias

Utilizing expert witnesses, as well as challenging the opinions of opposing experts, is one of the essential functions of today’s litigator. This article addresses the issue of uncovering expert witness bias using different techniques that are base upon theories of varying degrees of truthfulness.

As skilled practitioners have noted, it is important for attorneys to determine their “’theory’ of the cross: specifically, it must [be] determined if the suggestion to the jury is that the witness is truthful, honest but mistaken, or purposely exaggerating or shading [their] testimony to help one particular party.” Ben Rubinowitz & Evan Torgan, “Exposing an Expert Witness’s Bias during Cross-Examination: Collateral Attack,” New York Law Journal, 2013. An attorney’s strategy should vary depending on what the theory of the reason for the witness’s bias is. For example, in a case where a lawyer believes that an expert witness is intentionally trying to mislead a jury, the goal of the cross-examination should be to unearth the reason for that bias. Id. The types of questions an attorney should ask in such an instance should be ones that help demonstrate that particular experts are not as credible as they would have the jury believe. Id.

Generally speaking, practitioners who wish to expose bias experts have perhaps the best opportunity to do so by making use of cross-examination, through a technique known as the collateral attack. In fact, “[revealing] bias through the [utilization] of the collateral attack is one of the greatest and most time-tested [methods] available to counsel.” Id.

One basis for a collateral attack is to demonstrate that a given expert witness has a financial bias. However, as some practitioners warn, “to make the cross-examination on collateral matters even stronger, there are other avenues of attack that should be explored by before focusing solely on financial interests. While many of these avenues will eventually lead back to financial bias, and are indeed intertwine with the expert’s financial interests, these lines of questioning often provides independent [provider] for a compelling cross-examination.”Id.

So how does an attorney go about making a successful collateral attack? First, practitioners must do their homework. The internet is a valuable tool for researching information about and gathering ammunition against opposing expert witnesses. For example, “Not only are publications posted on the internet but disciplinary actions against the expert, resumes or curricula vitae, price lists, websites and jury verdict reporters, among other things, are posted there as well.” Id. By gathering as much information on an adverse witness before trial, attorneys will have the best opportunity to demonstrate bias by determining whether the expert has a financial, personal, or other motives for testifying. See id.

Collateral attacks can be particularly useful in cases where bias expert witnesses have exaggerated their credentials. An attorney who has thoroughly researched an expert and can expose any “exaggeration on the part of the expert regarding…credentials.” Finds that, “not only will that expert’s credibility quickly fade, but the attorney who called that witness to the stand will likely lose credibility with the jury as well.” Id.

Many avenues are open to litigators who wish to challenge expert witnesses. Attacks can be made via Motions in Limine, on voir dire, and during oral argumentation. However, perhaps one of the best ways to prove bias is through the collateral attack, which attorneys can make during cross-examination and which, if well-researched, may assist practitioners in diminishing or even eliminating the credibility of opposing expert witnesses.