When cross-examining the opposing expert at trial, stick to that old adage--leading questions only. Asking questions that call for either a "yes" or "no" is the best way to keep the opposing expert from giving that self-serving speech that he's just waiting present to the jury . . . and which he will present just as soon as you ask, frustrated at your own inability to elicit the testimony you want, "Well, what is your opinion based on?"
If you did a good job of deposing the expert before trial, your cross-examination won't be as difficult as it might seem. In fact, it should be constructed entirely of questions you have already asked. Consider this basic outline, which will work in many situations--
- Weaknesses in the witness’s experience and qualifications that call into question his authority to render the opinions he gave on direct.
- Deficiencies in the expert’s preparation to render an opinion.
- Assumptions the expert is making to support his opinion that will be disproved in your case.
- Admissions the expert made in his deposition that support--
- your facts and theories, and
- the qualifications, competence, and credibility of your expert and his methods.
Source note: The first paragraph of this post was written after browsing a chapter of On Trial: Lessons from a Lifetime in the Courtroom, by Henry G. Miller.