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Litigation: The hybrid fact/expert witness is a trap for the unwary

A look at what the Federal Rules of Civil Procedure require

In litigation, we typically assume that there are two types of witnesses: the fact witness who has direct knowledge of the issues in the case and the expert witness who will use her specialized knowledge, skill and/or experience to assist the judge and/or the jury understand the evidence. But oftentimes, these two witnesses are morphed into one — an expert in a particular field who has first-hand knowledge of, or involvement in, the underlying facts. This type of witness is called the hybrid fact/expert witness. The most-cited example of this hybrid witness is the treating physician but, there are many more examples in the commercial context — the employee accountant, engineer or scientist, among many others, who are experts in their particular fields and who may have familiarity with the facts of a particular case. Use of these types of fact/expert witnesses can enhance the effectiveness of the testimony they offer but, as recognized in Sullivan v. Glock, Inc., the disclosure requirements under Rule 26 of the Federal Rules of Civil Procedure can indeed become a “trap for the unwary.”

The disclosure requirements for hybrid witnesses pre- and post-2010 amendment

Contributing Author

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Stacey A. Bell

Stacey A. Bell is an attorney at BakerHostetler and can be reached at or 212.589.4632. She has a diverse complex commercial litigation background...

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