## Facts

- James Alphonzo Frye was tried in the Supreme Court of the District of Columbia and convicted of second-degree murder.
- Before trial, Frye submitted to a “systolic blood pressure deception test,” an early lie-detection technique premised on the idea that emotional stress associated with deception produces measurable blood-pressure changes.
- The defense offered the test administrator as an expert to testify that the test results indicated Frye was truthful.
- The government objected to admission of the expert testimony; the trial court sustained the objection.
- The trial court also refused the defense request to conduct the test in the jury’s presence.
- Frye appealed, assigning as error the exclusion of the deception-test evidence.

## Issues

1. Whether expert testimony based on a novel scientific technique (the systolic blood pressure deception test) is admissible when the technique has not been shown to have general acceptance in the relevant scientific field.

## Decision

- The Court of Appeals of the District of Columbia affirmed the conviction.
- The court held the deception-test evidence was properly excluded because the underlying scientific principle had not been shown to have gained general acceptance in its relevant field.
- The trial court did not err in excluding the expert testimony or in declining to allow a jury demonstration of the test.

## Legal Principles

- Expert opinion may be admitted when the subject is beyond common knowledge and requires specialized skill or knowledge.
- Scientific expert evidence derived from a 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.
- Courts may admit expert testimony based on well-recognized science, but will exclude evidence grounded in techniques that remain experimental or insufficiently established.

## Conclusion

The court upheld exclusion of lie-detector-style expert testimony because the systolic blood pressure deception test had not achieved general acceptance in the relevant scientific community, and it affirmed Frye’s second-degree murder conviction.


Frye v. United States, 293 F. 1013 (D.C. Cir. 1923)