5 Rules to Minimize Expert Contamination


Attorneys risk expert contamination when they provide information to an expert about a case. Although you need to discuss the case candidly and openly with your expert, you don’t want to contaminate the expert with information on the case’s weaknesses and problems. Five simple rules will help you minimize the risk of unnecessarily imparting harmful information to your expert.

  1. Use direct communication. The attorney handling the case should deal directly with the expert as much as possible. Don’t communicate with the expert through other attorneys, paralegals, secretaries, or investigators who may not understand the rules of discovery or who may be unaware of the sensitive areas of the case.
  2. Don’t reveal your worries about the case. Don’t volunteer your own fears and misgivings about the case to the expert. The expert need not know that you think a particular witness or a particular aspect of the case is weak or unreliable; what matters are the expert’s opinions and analyses. You can elicit these without disclosing your own misgivings. If you follow this rule, you can relax when the expert is asked during deposition or at trial to describe the entirety of his or her conversations with you on any particular subject.
  3. Don’t editorialize in writing. Minimize editorial comment in written communications with the expert. In sending depositions, interrogatory answers, physical evidence and the like to the expert, it’s seldom necessary to include anything more than a transmittal letter identifying the enclosures.
  4. Stay formal. Keep your written communications with the expert on a formal level even if you and expert know each other well. The expert should always be addressed formally you should sign all communications with your full name. A series of letters addressed “Dear Bonnie” and signed “Keep up the good work! Bill” can put both the author and the recipient in a needlessly compromising light if the letters are read to a jury by opposing counsel.
  5. Don’t give the expert more than is necessary. You shouldn’t supply the expert with unnecessary work product, e.g., deposition summaries, particularly if they contain your subjective evaluation. Many experts are too busy to read deposition transcripts, interrogatory answers, and other evidence in their entirety. You may be tempted to send the expert a summary, e.g., a copy of the letter summarizing the case that defense counsel has already sent to the insurance company. Such letters, however, frequently contain concessions, admissions, or similarly damaging statements, and they shouldn’t be made part of the expert’s potentially discoverable file. Having a younger associate or paralegal prepare objective deposition summaries just for the expert may be expensive and time-consuming, but it’s better than supplying the expert with deposition summaries and letters that weren’t intended to be read by the opposition or to a jury.

For more on practical considerations in dealing with your own expert, turn to CEB’s California Expert Witness Guide, chapter 8. On the use of experts in all phases of litigation, check out CEB’s Handling Expert Witnesses in California Courts. And in CEB’s On Demand program Preparing and Examining Expert Witnesses: Reports, Depositions and Cross-Examination, trial lawyers will take you step by step through the basics of selecting, preparing, and examining an expert witness in state court.

© The Regents of the University of California, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited.

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DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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