At trial, the defendant offered an expert witness to testify about the results of a systolic blood pressure deception test previously conducted on him. The theory of the test was that conscious deception produces a distinctive rise in systolic blood pressure that can be distinguished from ordinary nervousness caused by the examination itself. The government objected to the expert testimony, and the trial court sustained the objection. The court also refused the defendant's offer to have the expert perform the test in the jury's presence.
Issue
Whether expert testimony based on the results of a systolic blood pressure deception test was admissible, and whether the trial court erred in excluding that evidence because the underlying scientific principle had not yet achieved sufficient acceptance.
Rule
Expert testimony deduced from a scientific principle or discovery is admissible only when the thing from which the deduction is made is sufficiently established to have gained general acceptance in the particular field to which it belongs. Courts may admit expert testimony from well-recognized scientific principles, but not from principles still in the experimental stage without such general acceptance.
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One of 10 multiple-choice questions for this case. Pick an answer to see why.
In a robbery trial in Cleveland, Omar Bennett offers a neuroscientist from Lakefront Behavioral Labs to testify that a new "cortical hesitation scan" showed Omar was truthful when he denied involvement. The method has been described in a handful of preliminary studies, but most neurologists and psychologists have not accepted it as a reliable indicator of deception.
Should the trial court admit the expert testimony about the scan results?
Explanation. The governing rule is that testimony deduced from a scientific principle or discovery is admissible only when the underlying principle is sufficiently established to have gained general acceptance in the particular field to which it belongs. The fact that the subject is beyond common knowledge is not enough by itself. Here, the method remains only preliminarily supported and lacks general acceptance among the relevant authorities, so exclusion is proper. (Derived from Frye v. United States (1923).)