Also known as:testifying experts · testifying-expert · expert witness
Written by attorneys — see sources 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.
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How its tested
Common Examples
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Criminal Mental State Limitation
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.
DNA Profile Basis Opinion
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.
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.
General Acceptance Test
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.
Frye v. United States293 F. 1013, 1014 (D.C.Cir.1923)
Appellant, defendant below, was convicted of the crime of murder in the second degree, and from the judgment prosecutes this appeal. The case was submitted on November 7, 1923, and decided on December 3, 1923, by the Court of Appeals of the District of Columbia with Associate Justice Van Orsdel writing the opinion.
In the course of the trial counsel for defendant offered an expert witness to testify to the result of a deception test made upon defendant. The test is described as the systolic blood pressure deception test, and it is asserted that blood pressure is influenced by changes in the emotions of the witness, the systolic blood pressure rises being brought about by nervous impulses sent to the sympathetic branch of the autonomic nervous system.
Scientific experiments, it is claimed, have demonstrated that fear, rage, and pain produce a rise of systolic blood pressure, and that conscious deception or falsehood, concealment of facts, or guilt of crime, when accompanied by fear of detection while the person is under examination, raises the systolic blood pressure in a curve which corresponds to the struggle going on in the subject's mind between fear and attempted control of that fear as the examination touches the vital points in respect of which he is attempting to deceive the examiner.
Prior to the trial defendant was subjected to this deception test, and counsel offered the scientist who conducted the test as an expert to testify to the results obtained. The offer was objected to by counsel for the government, and the court sustained the objection. Counsel for defendant then offered to have the proffered witness conduct a test in the presence of the jury, and this also was denied.
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.
Joiner v. General Electric Co.522 U.S. 136, 142–43 (1997)
Robert Joiner began work as an electrician in the Water & Light Department of Thomasville, Georgia, in 1973. This job required him to work with and around the City’s electrical transformers, which used a mineral-oil-based dielectric fluid as a coolant. Joiner often had to stick his hands and arms into the fluid to make repairs. The fluid would sometimes splash onto him, occasionally getting into his eyes and mouth. In 1983 the City discovered that the fluid in some of the transformers was contaminated with polychlorinated biphenyls.
Joiner was diagnosed with small-cell lung cancer in 1991. He sued petitioners in Georgia state court the following year. Petitioner Monsanto manufactured PCB’s from 1935 to 1977. Petitioners General Electric and Westinghouse Electric manufactured transformers and dielectric fluid. In his complaint Joiner linked his development of cancer to his exposure to PCB’s and their derivatives, polychlorinated dibenzofurans and polychlorinated dibenzodioxins. Joiner had been a smoker for approximately eight years. His parents had both been smokers, and there was a history of lung cancer in his family.
Petitioners removed the case to federal court. Once there, they moved for summary judgment. Joiner responded that there were numerous disputed factual issues that required resolution by a jury. He relied largely on the testimony of expert witnesses. In depositions, his experts had testified that PCB’s alone can promote cancer and that furans and dioxins can also promote cancer. They opined that since Joiner had been exposed to PCB’s, furans, and dioxins, such exposure was likely responsible for Joiner’s cancer.
The District Court ruled that there was a genuine issue of material fact as to whether Joiner had been exposed to PCB’s. But it nevertheless granted summary judgment for petitioners because there was no genuine issue as to whether Joiner had been exposed to furans and dioxins. The testimony of Joiner’s experts had failed to show that there was a link between exposure to PCB’s and small-cell lung cancer. The court believed that the testimony of respondent’s experts to the contrary did not rise above subjective belief or unsupported speculation.
The Court of Appeals for the Eleventh Circuit reversed. It held that because the Federal Rules of Evidence governing expert testimony display a preference for admissibility, it applied a particularly stringent standard of review to the trial judge’s exclusion of expert testimony. The Supreme Court granted petitioners’ petition for a writ of certiorari.
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.
Baker v. General Motors Corp.522 U.S. 222, 246 (1998)
Ronald Elwell worked as an engineering analyst for General Motors Corporation from 1959 until 1989. For fifteen years he was assigned to the Engineering Analysis Group studying the performance of GM vehicles in product liability litigation, particularly those involving fires. He assisted GM lawyers in defending such suits.
Beginning in 1987 the Elwell-GM employment relationship soured. GM and Elwell first negotiated an agreement under which Elwell would retire after serving as a GM consultant for two years. When the time came for Elwell to retire, however, disagreement again surfaced and continued into 1991. A month later Elwell sued GM in a Michigan County Court alleging wrongful discharge and related tort and contract claims. GM counterclaimed that Elwell had breached fiduciary duties by disclosing privileged and confidential information and misappropriating documents.
Following a hearing, the Michigan trial court on November 22, 1991, enjoined Elwell from consulting or discussing with or disclosing to any person any of General Motors Corporation's trade secrets, confidential information or matters of attorney-client work product relating in any manner to the subject matter of any products liability litigation whether already filed or to be filed in the future which Ronald Elwell received, had knowledge of, or was entrusted with during his employments with General Motors Corporation. In August 1992 the parties settled for an undisclosed sum. They jointly submitted a stipulated permanent injunction that the Michigan court entered without further hearing. The injunction comprehensively enjoined Elwell from testifying, without the prior written consent of General Motors Corporation, either upon deposition or at trial, as an expert witness, or as a witness of any kind, and from consulting with attorneys or their agents in any litigation already filed, or to be filed in the future, involving General Motors Corporation as an owner, seller, manufacturer and/or designer of the product(s) in issue. The separate settlement agreement stated that court-ordered testimony would in no way form a basis for an action in violation of the Permanent Injunction or this Agreement.
In February 1990 Beverly Garner died when the engine of her 1985 Chevrolet S-10 Blazer caught fire after a Missouri highway collision. Her sons Kenneth and Steven Baker filed a wrongful-death product liability suit against GM in Missouri state court in September 1991. They alleged a defective fuel pump caused the post-collision fire. GM removed the case to federal court on diversity grounds. GM defended on the merits that the fuel pump was not faulty and that impact injuries alone caused the death. The Bakers sought to depose Elwell and call him at trial. GM objected on the basis of the Michigan injunction. After in camera review of the injunction and settlement agreement the Missouri federal district court permitted Elwell's deposition and trial testimony. The court relied on alternative grounds that Missouri public policy favored disclosure of relevant nonprivileged information and that the injunction was modifiable.
At trial Elwell testified in support of the Bakers' fuel-pump defect claim. He identified a 1973 internal GM memorandum concerning fuel-fed engine fire risks. The jury returned an $11.3 million verdict for the Bakers. The district court entered judgment on the verdict. The Eighth Circuit reversed. It held that Elwell's testimony should not have been admitted because the Michigan injunction controlled. Missouri's public policy favoring full faith and credit outweighed any disclosure policy. The Supreme Court granted certiorari to decide whether the full faith and credit requirement stops the Bakers from obtaining Elwell's testimony in their Missouri action.
What discovery obligations attach once a party designates an expert as a testifying witness?
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.
How does Rule 704(b) limit a testifying expert in a criminal case?
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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May a testifying expert rely on data generated by a non-testifying laboratory without triggering confrontation concerns?
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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What must a party show to overcome work-product protection for materials shared with a non-testifying consultant?
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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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