Victory for Science in OUI-Marijuana Prosecutions

Are the standardized field sobriety tests reliable scientific tests that can determine impairment by marijuana? In short, the answer is no. The Massachusetts Supreme Judicial Court issued a decision this week addressing this question. Murphy & Rudolf’s own Attorney Tansley has been litigating this case since 2013.

The standardized field sobriety tests were developed to detect alcohol impairment. An operator’s performance on the walk and turn (WAT) and the one leg stand (OLS) have been scientifically proven to correlate with alcohol impairment and BAC levels exceeding the legal limit of .08. As a result, police officers are permitted to testify in court that it is their opinion that an operator was impaired based on poor performance in these tests.

The same is not true of marijuana. Scientific research remains inconclusive on the reliability of these standardized tests to determine if an operator is under the influence of marijuana. Given this lack of scientific agreement, the Supreme Judicial Court ruled that officer testimony should be limited. Moving forward when testifying about suspected marijuana impairment:

  1. officers must refer to the “one leg stand” and “walk and turn” as assessments rather than tests
  2. officers may not testify that an operator “passed” or “failed” the assessments
  3. officers may not suggest or testify that performance on the assessment established that the operator was under the influence of marijuana.

Officers are still permitted to testify about their observations of the operator during these assessments, however, “it must be made clear to the fact finder that the WAT, the OLS, and the other field sobriety tests do not directly test marijuana impairment.” Gerhardt decision, p. 17. Defendants will be entitled to an instruction given to the jury that clearly states, “evidence of how a defendant performed in roadside assessments, standing alone, is never enough to convict a defendant of operating under the influence of marijuana.” Model Jury Instructions, Gerhardt decision.

Attorney Tansley is pleased that her client’s case will progress with only relevant and scientifically valid evidence presented to the judge or jury.

If you need a Massachusetts OUI Attorney contact Murphy & Rudolf, LLP at (508) 570-3037 and we can help you with your case.

SJC decision:

Boston Globe article:

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