## Facts

- A Planned Parenthood clinic in the Detroit area was firebombed, and police apprehended Hayward Leslie Brown near the clinic.
- Investigators recovered hair of unknown origin at the crime scene.
- A federal grand jury in the Eastern District of Michigan indicted Brown for (1) possession of three Molotov cocktails as unregistered “destructive devices” under 26 U.S.C. §§ 5845, 5861(d), 5871, and (2) damaging a federally assisted institution by means of an explosive under 18 U.S.C. § 844(f).
- Brown confessed to involvement in the firebombing; investigators later obtained a hair sample from him.
- At trial, the government offered expert testimony using ion microprobe (ion microprobic) analysis to compare trace-element content in the crime-scene hair and Brown’s hair.
- Two government experts, Michael Bayard and Dr. Robert Muggli, used charts derived from ion microprobe testing and a “test group” of 130 hair samples (primarily from White individuals living in Chicago) to opine that Brown was the source of the unknown hair.
- The district court admitted the ion microprobe testimony and related charts, and the jury convicted Brown on both counts.
- Brown appealed, chiefly challenging the admissibility of the ion microprobe hair-comparison evidence.

## Issues

1. Whether ion microprobe hair-comparison evidence was admissible as novel scientific evidence under the Frye “general acceptance” standard.
2. Whether the district court committed reversible error by admitting the ion microprobe expert testimony and charts.
3. Whether any evidentiary error was harmless in light of Brown’s confession and other evidence.

## Decision

- The Sixth Circuit reversed the convictions and remanded.
- The court held that ion microprobe hair analysis, as presented, lacked the required showing of general acceptance in the relevant scientific field and therefore should not have been admitted.
- The court concluded the error was prejudicial, not harmless, because the scientific identification evidence likely carried substantial weight on the question of identity.

## Legal Principles

- Trial courts have discretion over admission of expert testimony, but that discretion is constrained when the proffer involves a novel scientific technique.
- Scientific evidence is admissible only if the underlying principle and method are sufficiently established to have gained general acceptance in the relevant scientific field (Frye standard).
- “General acceptance” is closely tied to demonstrated reliability and sufficient accuracy; unanimity or absolute certainty is not required.
- When improperly admitted scientific evidence bears directly on identity and is presented with expert authority, it may have an outsized effect on the jury and require reversal if not harmless.

## Conclusion

The Sixth Circuit required exclusion of ion microprobe hair-comparison testimony because the government failed to show the technique had achieved general acceptance and demonstrated reliability as an identification method, and it reversed Brown’s convictions because the erroneous admission was not harmless.


United States v. Brown, 557 F.2d 541 (6th Cir. 1977)