Also known as: expert opinions · expert testimony · opinion testimony · expert witness testimony · Rule 702 testimony
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Opinion testimony by a witness qualified through knowledge, skill, experience, training, or education on a subject requiring scientific, technical, or other specialized knowledge. The testimony must be relevant and rest on reliable principles and methods applied reliably to the facts of the case. Courts serve as gatekeepers to exclude opinions lacking sufficient factual support or a reliable methodology.
Esther Eisenberg, a forensic engineer, testified that a manufacturing defect caused a machine failure even though she had not observed the machine in operation. The court admitted her opinion because the personal knowledge requirement of Rule 602 does not apply to expert testimony. Her conclusions rested on data of the type reasonably relied upon by engineers in the field.
Ethan Evans offered expert testimony that a chemical exposure caused the plaintiff's illness based solely on animal studies never validated in humans. The district court excluded the opinion after finding the methodology untested and lacking peer review or known error rates. The gatekeeping function required exclusion of the unreliable evidence.
Edgar Evers, a toxicologist, concluded that a defendant's product caused the plaintiff's specific symptoms, yet the underlying studies addressed only general causation. The court found too great an analytical gap between the data and the proffered opinion. It therefore excluded the testimony on reliability grounds.
Elena Estrada, an automotive engineer, testified that a tire design was defective based on specialized technical analysis. The court applied the flexible reliability inquiry to the engineering testimony rather than limiting review to scientific methods alone. It admitted the opinion after confirming appropriate standards and controls.
Enzo Eastwood sought to introduce expert testimony on a novel lie-detection technique. The court required the proponent to show the method enjoyed general acceptance in the relevant scientific community. Because the technique lacked such acceptance, the testimony was excluded.
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.
View caseEmmett Egan presented expert economic analysis to quantify the ratio of punitive to compensatory damages in an insurance bad-faith case. The court considered the expert's methodology to ensure the ratio remained within constitutional bounds. The testimony helped the jury evaluate the appropriate amount without producing an arbitrary award.
In 1981, Curtis Campbell was driving with his wife Inez in Cache County, Utah, when he attempted to pass six vans on a two-lane highway. This caused an oncoming driver, Todd Ospital, to swerve onto the shoulder, lose control, and collide with a vehicle driven by Robert G. Slawson and his wife, killing Ospital and permanently disabling Slawson. Campbell's insurer, State Farm Mutual Automobile Insurance Company, declined settlement offers of the $50,000 policy limit from Slawson and Ospital's estate despite early investigations indicating Campbell's fault and advice from its own adjuster. A jury in the underlying tort actions found Campbell 100 percent at fault and returned a judgment of $185,849 against him. State Farm refused to pay the $135,849 excess over policy limits or post a supersedeas bond. The Campbells then entered an agreement with Slawson and Ospital's estate under which the claimants would not seek satisfaction of the judgment in exchange for the Campbells pursuing a bad-faith action against State Farm, being represented by the claimants' attorneys, and assigning 90 percent of any recovery to them. The Campbells sued State Farm for bad faith, fraud, and intentional infliction of emotional distress. The trial court bifurcated the case into two phases before separate juries. In phase one the jury found State Farm's refusal to settle unreasonable. In phase two the jury heard evidence that State Farm's decision was part of a nationwide Performance, Planning and Review policy implemented since 1979 to cap payouts and meet corporate profit goals, including testimony from former Utah employees and experts about practices in multiple states over twenty years. The jury awarded $2.6 million in compensatory damages and $145 million in punitive damages. The trial court reduced the compensatory award to $1 million and the punitive award to $25 million. Both sides appealed. The Utah Supreme Court reinstated the $145 million punitive damages award after applying the three guideposts from BMW of North America, Inc. v. Gore and relying on the nationwide evidence, State Farm's wealth, and the statistical likelihood of punishment in only one of 50,000 cases. The United States Supreme Court granted certiorari.
View caseThe witness must demonstrate knowledge, skill, experience, training, or education sufficient to assist the trier of fact on the subject. Qualification is assessed relative to the specific issues in the case rather than requiring formal academic credentials in every instance.
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Courts evaluate factors including whether the theory has been tested, subjected to peer review, possesses a known error rate, maintains controlling standards, and enjoys general acceptance. The inquiry remains flexible and case-specific rather than applying a rigid checklist.
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Appellate courts review the decision for abuse of discretion. The trial court's gatekeeping determination receives substantial deference provided the court adequately assesses both relevance and reliability.
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Yes. An expert may rely on facts made known at trial, supplied through hypothetical questions, or drawn from materials of a type reasonably relied upon by experts in the field even without personal observation.
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