Cross-Examining Expert Witnesses

Cross-examining the expert for the adverse party is one part of a trial that makes an attorney really feel like lawyer. We’ve seen hundreds of lawyers on television and in movies tear up an opponent with a sizzling cross, and we can’t wait to do the same in our case.

However, attacking an adversary’s expert is not always best for a client’s case. An attorney should first consider what that expert might say that would be beneficial to his client’s case. The attorney can focus on the areas in which the adversary’s expert agrees with the expert he has hired to testify for his client, for example, or that adversary expert can be used to acknowledge something favorable about the plaintiff’s injuries. The attorney can bring out those favorable admissions from the expert before attacking him either directly or indirectly.

The most direct way to attack an expert is by challenging his underlying theories, assumptions or logic. If an attorney can show that the expert used flawed reasoning or made an error in computation, the expert’s credibility may be destroyed. However, this frontal attack is dangerous in that the expert usually knows the field better than the attorney and may be able to deftly sidestep the attack. That is why many attorneys choose to attack experts from various other angles.

One such attack is on the expert’s credentials, which are often spelled out in his resume or curriculum vitae, but can also be supplemented by an internet search. An attorney might focus not on what the expert has accomplished, but on what he hasn’t. Failure to attain board certification, failure to publish articles, lack of work experience in the field pertinent for this case are just some of the usual attacks that can cause a jury to question the witness’ expertise.

Just as all experts have qualifications that may be subject to attack, they all have biases that may be exploited. One way to do so is to attack the expert based upon the amount of money he is paid for testifying. This is usually fruitful only if his fees are outrageous, or if an inordinate percentage of his income comes from testifying in court, particularly for just one side of the bar (a hired gun). For example, if the expert testifies for plaintiffs 90% of the time, an attorney might delicately suggest that if the expert had not given a report favorable to the plaintiff in this case, his future livelihood was at stake.

One of the most effective cross-examination techniques involves showing how the expert’s opinion differs from other experts in the field. The attorney needs to have at the ready a publication by a recognized authority that contains statements which disagree with that which the expert has already testified. If a plaintiff’s expert testifies that the machine manufactured by the defendant in 1950 should have included a particular guard, an authoritative book which indicates that such guards were not generally available until much later or that such a guard would make the equipment more dangerous would be effective to impeach the expert.

Finally, an expert is subject to attack if the facts on which he relied in forming his opinions are disputed. Did he assume the opening between the machine’s rollers was two inches when the evidence suggests it was actually four inches? The attack here is not so much on the expert himself but on the foundation upon which his opinions rest.

The approach this firm takes towards cross-examining experts varies from case to case and from one type of expert to another. An expert physician testifying as to medical causation and/or damages must be handled differently than an expert engineer testifying as to defect and causation. The general precepts outlined above are often considered for each expert before a particularized plan is established for that expert witness. No matter which of the potential avenues of attack listed above are employed, the goal is to recast that expert’s testimony in a light most favorable to our client, whatever that may be in a given case.

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