Also known as: testifying experts · testifying-expert · expert witness
Written by attorneys · grounded in primary & secondary sources — see below
An expert witness identified by a party as one expected to testify at trial. The designation triggers disclosure obligations including production of a report and availability for deposition that do not apply to experts retained only for consultation.
Thaddeus Tran faces federal charges requiring proof of specific intent. The government designates Dr. Elena Voss as its testifying expert to explain financial records. At trial Voss stops short of stating whether Tran possessed the required intent, leaving that inference for the jury alone.
Tori Taylor is prosecuted for assault. The state calls forensic analyst Marcus Reed as its testifying expert. Reed bases his match opinion on a DNA profile generated by an out-of-state lab and explains the profile only to show the foundation for his independent conclusion.
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Tamara Tan sues a pharmaceutical company alleging injury from a medication. Her testifying pharmacologist cites a journal article on direct. On cross-examination defense counsel calls the pharmacologist's attention to a contrary passage in the same journal. The passage is read into the record but not received as an exhibit.
Tobias Thomas offers expert testimony that a novel blood-pressure deception test proves the defendant lied. The trial court excludes the testimony after finding the underlying technique has not gained general acceptance in the relevant scientific community.
Tiffany Torres designates an engineer to opine that a product defect caused her injuries. The expert's data show only modest temperature increases. The court excludes the opinion because the leap from those data to the conclusion of causation creates too great an analytical gap.
Tanner Thompson obtains a judgment in State A that includes an award of expert witness fees. When Thompson seeks enforcement in State B, the court recognizes the fee component as part of the enforceable judgment under full faith and credit principles.
The designation requires production of a written report containing the expert's opinions, the facts and data considered, and exhibits to be used. The expert must also be made available for deposition. These obligations do not apply to experts retained solely for consultation.
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The expert may not state an opinion on whether the defendant possessed a mental state or condition that constitutes an element of the crime or a defense. That determination remains exclusively for the trier of fact.
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Yes, when the out-of-court report is offered only to explain the basis of the expert's independent opinion and was not prepared primarily to accuse a targeted individual.
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Opinion work product containing mental impressions and legal theories remains protected even if substantial need is shown. The court must still shield those core materials from disclosure.
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…Center conceded liability for the lost transparencies and the issue of damages was tried before a jury. At trial, Gasperini's expert witness testified that the "industry standard" within the photographic publishing community valued a lost transparency at $1,500. See id. , at 227. This industry standard, the expert explained,…