1. Make Him or Her Your Own Expert. Professor McElhaney suggests you look for places where your opponent’s expert agrees with your theories in the case. For example, if, in a personal injury case, both experts mostly agree on the severity of the damages and future treatment, but differ on causation, focus on where there is agreement. He says:
“Note that the defendant’s own doctor admits that the plaintiff will be subject to sudden seizures for the rest of his life; that this form of epilepsy can only be treated, not cured; and that the plaintiff’s condition can put him out of work as a machinist and means he can never drive again.
If you have a strong case on causation, you may decide it is better to make this witness your own on the issue of damages than to try to beat him down on the subject of cause.” (Litigation (ABA 1995) 165.)
2. Attack His or Her Qualifications. “No matter how well-qualified the witness,” McElhaney reminds us, “there is always a higher level he has not reached.” (Id.) Used subtly, this can also serve to bolster your expert’s credibility if he/she has better credentials.
3. Narrow His or Her Expertise. Professor Mauet points out that, “[o]ften an expert will appear to be highly qualified, yet his actual expertise and experience are in areas different from those involved in the case. The cross-examination technique is to build up the witness’ real expertise, then show that this particular expertise is not directly applicable to the type of case on trial.” (Fundamentals of Trial Techniques (3rd Ed. 1992) at 266.)
4. Attack His or Her Facts. I see two possibilities here. One is if you can establish an opinion rests on a faulty or controversial factual premise, such as a date, measurement or time. The other, highlighted by McElhaney, capitalizes on the fact the expert did not do factual investigation himself, but is relying instead on the reports of others. He gives an example of an effective examination:
“Q. Doctor, can we agree that your opinion can be no better than the information on which it is based?
A. Well, yes, I guess so.
Q. If the information you have is not accurate, then the opinion would have to suffer too?
A. Of course.
Q. Which is why you would rather gather the information yourself than have to trust some source you have not worked with before?
Q. But you were not given an opportunity to do that in this case?
A. Well, not exactly. No, I wasn’t.” (Litigation, 167.)
5. Vary The Hypothetical. McElhaney explains this approach as follows:
“You are permitted to change the facts around to see at which point they alter the expert’s opinion — depending on whether the question on direct examination originally was asked as a hypothetical.
You can insert facts you feel were left out on direct, or take out facts you feel should not have been included.” (Id.)
Let me go on record here that I view this as an advanced technique, and an opportunity to ruin an otherwise solid cross-examination. Ideally, you would have covered this ground with the witness in a pre-trial deposition, so you know what the answer should be and can hold the witness accountable if he/she strays. Otherwise, an experienced expert might hand you your head on a stick if you are not meticulously prepared.
6. Use The Expert To Bolster Your Own Credibility. Mauet suggest it can be “useful to cross-examine an expert to establish your own expertise in the subject. You can do this by defining technical terms or describing technical procedures and having the expert agree that you have defined or described them correctly. Use a treatise to obtain accurate definitions and descriptions. If this expert disagrees, you can impeach him with the treatises.” (Fundamentals, 267.)
7. Establish His or Her Compensation Bias. Mauet writes: “Inquire into professional fees charged and whether they have already been paid.” But he reminds us to “[k]eep in mind . . . that trials are a two-way street. Your opponent can do to you what you contemplate doing to him. Before pursuing this approach, make sure your own experts are less vulnerable than your opponent’s.” (Id., 266.)
8. Identify Additional Steps The Expert Did not Take. Mauet suggests we “[d]emonstrate that the witness did not do all the things a thorough, careful expert should have done. Demonstrate that a variety of tests could and should have been performed to arrive at a reliable opinion in this case.” (Id., 267-68.)
There. Now go get ‘em.