Part 1 of this article […trategies-part-1/] detailed the suggested approaches and checklists of several advocacy experts on how to confront and cross-examine the opposing expert witness.  Those checklists, while all useful, paid inadequate heed to the interplay of courtroom skills and evidence law.  In part 2, this article suggests a more comprehensive paradigm for confronting adverse experts at trial.


  1. Prevention

Better than an effective cross-examination is the condition of having no expert to question.  Although not often successful, challenges to the reliability or general acceptance of the testimony, or to the absence of “fit” [relevant to the particulars of the case even if reliable in general, see, e.g.  ]; or to the testimony not being “helpful” in the particular case because the jury does not need the assistance, all must be explored.  [For expert testimony to meet the Daubert “fit” requirement, it must assist the trier of fact to understand the evidence or to determine a fact in issue…Expert testimony must relate to the specifics of the case at hand.  In re Blood Reagents Antitrust Litig., No. 09-2081 ALL, 2015 U.S. Dist. LEXIS 141909, at *26 (E.D. Pa. Oct. 19, 2015).]

A second component of a “prevention” strategy” is an attack on credentials and qualifications.  Rarely, however, are experts excluded solely because of a lack of knowledge, experience or education.

  1. Narrowing

Where exclusion is not possible, narrowing the permissible range of opinions the expert may give – because the opinions are beyond the scope of the expert’s qualifications or are based on an inadequate theory or foundation – is the next step before the witness begins to testify.

  1. Diminishing the Expert’s Qualifications

It is always a dilemma as to how much to press an expert, on cross, during the “tender” or expert voir dire in front of the jury because regardless of what questions will be asked it is a virtually certainty that the Judge will nonetheless permit the expert to proceed with opinion testimony (and, in some jurisdictions, the Judge will pronounce the witness to be an expert).  But where the qualifications are weak – either in absolute terms or relative to the credentials the examiner’s own expert possesses – this must be highlighted, and if lawyers do not press the issue during the preliminary question it might be deemed waived if attempted during the cross-examination after the opinion has been rendered.

Questions may encompass the expert’s lack of particular work experience or exposure to specific types of evidence or events; the absence of a license, certification or other credential; and/or an emphasis on how the expert’s actual field of concentration is quite different from the issue before the factfinder.

If such a cross is conducted, counsel then has a tactical decision to make given the virtual certain outcome that the expert will not be excluded – to grudgingly concede expertise or to nonetheless make argument in front of the jury.  The difference looks like this:

Grudging Concession: Your Honor, we have nothing further.  The witness has the basic credentials to give an opinion.

The Losing But Pointed Argument: Your Honor, the expert may know a great deal about veterinary care of horses, and has spent the last ten years working with them, but this case involves veterinary care of rare animals in a zoo.  This is not the proper expert for this case.

Where the credentials and experience to not permit a meaningful challenge on cross, counsel opposing the expert may “diminish” by trying to forestall the proponent from fully credentialing the witness.  Sometimes, when opposing counsel says “Your Honor, we will stipulate that the witness is an expert in the subject matter” the proponent forgets that she/he still has the right to present the credentials in order for the jury to value and weigh the opinion.  Then the jury hears no background information and lacks one measure of the quality of the witness’ beliefs and conclusions.

  1. Inhibiting the testimony Via Rule 703

Experts are permitted to rely on inadmissible evidence but may not repeat what is inadmissible unless the probative value of the same outweighs the clear prejudice – the jury using the inadmissible evidence for its truth.  The expert may say “I also spoke with five other people and read seven reports,” but if the reports and what the people said are not admissible under hearsay exceptions or exemptions then the expert has to stop there and not divulge content.

A motion to preclude mention of the inadmissible evidence is sure to tie some experts and lawyers in knots.  In one reported decision, when the lawyer was told the expert could not discuss the contents of reports that were relied on, the attorney withdrew the expert entirely, not understanding that the expert could still proffer an opinion.  Binakonsky v. Ford Motor Co., 4 F. App’x 161, 164 (4th Cir. 2001).  And even where the expert does testify, the inability to reveal contents of interviews or documents may render the presentation less smooth and less persuasive.

  1. Inadequacies in Foundation

Separate from a legal challenge to admissibility is the credibility challenge to the inadequacies in foundation.  Here there are two potential attacks – information the expert never considered; and information the expert relied upon but that can be proved faulty, incomplete or untruthful.  Where opposing counsel can show that some of the underlying ‘facts’ are inaccurate or incomplete, the expert should first be locked in to acknowledging that the opinion rendered was based on a collection of facts and the presumption that each one was accurate; and then the expert should be pressed to concede that if some of those facts are wrong then the opinion might not be valid.  With that concession, counsel then demonstrates, by cross and/or with extrinsic proof, each ‘fact’ that is counter to the expert’s assumption.

  1. Inadequacies in Application

This attack requires a mastery of the expert’s field and may be tried on cross-examination or by extrinsic proof.  It involves a demonstration that the testing or analysis was not performed adequately – application of the Rule 702 and Daubert principle that the expert has reliably applied the principles and methods to the facts of the case.  While a threshold admissibility standard, this same requirement is appropriate for cross-examination and a challenge to the weight of the opinion being offered.

  1. Making the Opposing Witness Your Expert

It is, or should be, rare that experts are diametrically opposed in their opinions and foundational premises.  To the extent possible [and before challenging this expert’s inadequacies or errors], an important task of the cross-examiner is to elicit points of agreement.  This may take any of three forms: having the opposing expert acknowledge your expert’s qualification; establishing agreement with fundamental principles, either principles your expert has testified to or will testify to or those of the field as set forth in a learned treatise; and showing where the opposing expert endorses any of your expert’s conclusions.

All of these ideas are premised on intensive preparation by counsel – immersing oneself in the area of specialized knowledge and engaging in extensive pre-trial preparation with your own expert, both to make her testimony comprehensible and to help identify and best articulate the weaknesses in the opposing expert’s positions.  With that preparation, and knowing the limits of what can be achieved in any particular case, the cross-examination of the opposing expert may prove both less daunting and more fruitful.