It is usually important to explain to your expert witness some of the rules and procedures governing depositions and why these are important to the expert witness.
The authors have found that even very experienced expert witnesses often do not appreciate the law and procedures governing depositions, such as:

• “Off the record” merely means that the court reporter is not recording what is said.

o Off the record remarks can and will be used against your expert witness.
o Experts should always assume that what they say during deposition (or at any time, with anyone, including counsel or an off-the-cuff comment to a colleague) will be “on the record” and potentially used against them. All conversations about the case are discoverable unless privileged.
• Whether the deposition will be videotaped.

• What the standard stipulations mean.
• Lawyers are allowed under the rules to ask all types of probing questions at a deposition. They are also allowed to probe with questions that may lead to information on the expert’s credibility.
o Your expert should not get flustered, but he should roll with the punches and just answer the questions. Remind him that he is getting paid for his time.
o The deposition’s time may be limited, so opposing counsel wasting time on trivialities can actually help the expert witness in the long run.
o Just because opposing counsel can ask your expert a question at deposition in no way means that the answer will be admissible over an objection at trial.
• The rules in your jurisdiction as to what must be answered regarding communications between you as retaining counsel and your expert witness.
• What reading and signing means—the opportunity to review the transcript for transcription errors or to change testimony.
o Your expert should not waive his right to read and sign.
• Discuss the rules in your jurisdiction regarding the appropriateness, limits, and discoverability of conversations between you and your expert at breaks in the deposition.
• Explain to your expert that you are only allowed to object at a deposition for limited reasons.
o In most cases, even with an objection, your expert will still need to answer the question.
o The expert should listen closely to the stated reason for the objection as this may contain helpful information.

Excerpted from the SEAK text:  How to Prepare Your Expert Witness for Deposition