Commonwealth v. Gerhardt
477 Mass. 775
| Mass. | 2017Background
- Trooper observed a vehicle with no rear lights, smelled burnt marijuana, and recovered partially-smoked "roaches"; driver Gerhardt admitted smoking and said it was hours earlier.
- Trooper administered standard field sobriety tests (FSTs): horizontal gaze nystagmus (HGN), walk-and-turn (WAT), one-leg stand (OLS), and simple cognitive tasks; trooper concluded Gerhardt was impaired.
- Gerhardt was charged with operating under the influence of drugs (marijuana) under G. L. c. 90, § 24 and sought a Daubert-Lanigan hearing to exclude FST evidence linking performance to marijuana impairment.
- District Court reported four questions to the Appeals Court about admissibility of FSTs and lay testimony on marijuana effects; SJC granted direct review and remanded for further findings before deciding.
- The SJC considered scientific literature showing mixed results on whether standard FSTs correlate with marijuana impairment and distinguished alcohol-context reliability from marijuana-context uncertainty.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| May police testify to administration/results of standard FSTs in marijuana prosecutions as they do for alcohol? | Commonwealth: FST observations are probative and admissible like in alcohol cases. | Gerhardt: Scientific uncertainty about marijuana makes FSTs unreliable and inadmissible as impairment evidence. | No. Officers may describe "roadside assessments" (observations of performance) but may not state pass/fail or that results established marijuana impairment. |
| May a lay witness opine that a person is "high" on marijuana? | Commonwealth: Officers' lay opinions on intoxication are useful to jurors. | Gerhardt: Effects of marijuana are not within common knowledge; lay opinions risk unreliability. | No. Lay witnesses may not offer an opinion that another person is "high" on marijuana. |
| May an officer (non-expert) testify to physical signs (bloodshot eyes, lack of coordination, etc.)? | Commonwealth: Such observable signs are admissible as lay testimony. | Gerhardt: Risk of impermissible inference to marijuana impairment. | Yes, officers may testify to observed physical characteristics but may not say those signs mean the driver was under the influence of marijuana. |
| May jurors rely on their common experience about marijuana effects? | Commonwealth: Jurors may use common sense to weigh evidence. | Gerhardt: Juror common sense should not substitute for expert proof given scientific uncertainty. | Yes. Jurors may use common sense, but FST evidence alone is insufficient to convict; judges should give limiting instructions. |
Key Cases Cited
- Daubert v. Merrell Dow Pharms., 509 U.S. 579 (Daubert admissibility framework for scientific evidence)
- Commonwealth v. Lanigan, 419 Mass. 15 (adopting Daubert principles in Massachusetts)
- Commonwealth v. Sands, 424 Mass. 184 (HGN requires expert testimony)
- Commonwealth v. Canty, 466 Mass. 535 (limits on lay opinion about intoxication)
- Commonwealth v. Daniel, 464 Mass. 746 (proof required in DUI prosecutions)
- Commonwealth v. Jackson, 384 Mass. 572 (use of limiting instructions)
- Commonwealth v. Lykus, 367 Mass. 191 (jurors as ultimate factfinders)
- Commonwealth v. Thomas, 476 Mass. 451 (admissibility and weight when scientific consensus lacking)