By James J. Mangraviti, Jr., Esq.

There is a long-standing policy in American law encouraging vigorous, thorough cross-examination of expert witnesses.  Attorneys are generally given wide latitude when cross-examining experts.  What is and is not allowed to be asked during cross-examination is in the discretion of the trial judge, subject to the applicable rules of evidence in the jurisdiction in question.  A trial judge’s ruling on an evidentiary matter such as the scope of cross-examination will only be overturned on appeal for an abuse of the judge’s discretion.  Despite the fact that cross-examination is meant to be vigorous and thorough, there are some restrictions on the extent of cross-examination of an expert.  These include the following:

• Irrelevant questions.  (Keeping in mind that the expert’s credibility is a relevant issue.  Questions concerning the expert’s potential bias or pecuniary interest in the case, the factual bases for the expert’s opinions, and the expert’s qualifications are also relevant.)
• Questions where the evidentiary (i.e., probative) value of the answer is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.
• Limits on the use of extrinsic evidence to prove prior bad acts on the part of the expert on collateral matters.
• Harassing questions or questions that would cause the expert undue embarrassment.
• Impeachment with a prior inconsistent statement when, in fact, the prior statement is not inconsistent.
• Impeachment with a so-called “learned treatise” when the text in question has not been properly established as a reliable authority.
• Questions that would violate a privilege.

Experts should be familiar with the major legal principles regarding the allowable scope of cross-examination.

James J. Mangraviti, Jr., Esq., has trained thousands of expert witnesses through seminars, conferences, corporate training, training for professional societies, and training for governmental agencies including the FBI, IRS, NYPD, Secret Service, and Department of Defense.  He is also frequently called by experts, their employers, and retaining counsel to train and prepare individual expert witnesses for upcoming testimony.  Mr. Mangraviti assists expert witnesses one-on-one with report writing, mentoring, and practice development.  He is a former litigator who currently serves as Principal of the expert witness training company SEAK, Inc. (  Mr. Mangraviti received his BA degree in mathematics summa cum laude from Boston College and his JD degree cum laude from Boston College Law School.  Mr. Mangraviti has designed dozens of expert witness training programs and has personally taught experts in a group setting over 200 times since 1997. He is the co-author of thirty books, including:

How to Be an Effective Expert Witness at Deposition and Trial: The SEAK Guide to Testifying as an Expert Witness; How to Be a Successful Expert Witness: SEAK’s A–Z Guide to Expert Witnessing; How to Write an Expert Witness Report; How to Prepare Your Expert Witness for Deposition; The Biggest Mistakes Expert Witnesses Make and How to Avoid Them; and  How to Market Your Expert Witness Practice: Evidence-Based Best Practices.

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