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Mass. Supreme Court: Field Sobriety Tests Inadmissible Re: Marijuana

by Christopher Zoukis

The Massachusetts Supreme Court ruled that field sobriety tests (“FSTs”) may not be used as definitive evidence of impairment in cases involving allegations of operating a motor vehicle while under the influence of marijuana. The Court also ruled that FSTs are admissible as contemporaneous observations of the police officer, as a lay witness, who conducted the assessment.

Massachusetts decriminalized the use of marijuana in 2016 but still criminalizes the operation of a motor vehicle while under the influence of marijuana. In order to establish the crime of driving under the influence of marijuana, the Commonwealth must prove beyond a reasonable doubt that “a defendant’s consumption of marijuana impaired his or her ability to drive a motor vehicle safely.”

FSTs have long been admissible to directly establish impairment in drunk driving cases. Indeed, FSTs “were developed specifically to measure alcohol consumption, and there is widespread scientific agreement on the existence of a strong correlation between unsatisfactory performance and a blood alcohol level of at least 0.08%.” Reviewing available studies, however, the Massachusetts Supreme Court found that “there is as yet no scientific agreement on whether, and, if so, to what extent, these types of tests are indicative of marijuana intoxication.”

As such, the Court ruled that FSTs cannot be used “as scientific tests establishing impairment as a result of marijuana consumption.”  Furthermore, the jury must be so instructed.

Since FSTs are still relevant and probative evidence, the Court did not prohibit them in marijuana intoxication cases altogether. Instead, the high court ruled that “to the extent that they are relevant to establish a driver’s balance, coordination, mental acuity, and other skills required to safely operate a motor vehicle, FSTs are admissible at trial as observations of the police officer conducting the assessment.”

The Supreme Court limited the purpose for which FST results are admitted into evidence. When used as evidence of the officer’s observations, the Court made it clear that no testimony as to whether the driver’s performance amounted to a “pass” or a “fail” would be permissible.

“A police officer may not suggest … on direct examination that an individual’s performance on an FST established that the individual was under the influence of marijuana,” instructed the Court. “Likewise, an officer may not testify that a defendant ‘passed’ or ‘failed’ any FST, as this language improperly implies that the FST is a definitive test of marijuana use or impairment.”

The Court also decided the related question of whether a police officer, or any other lay witness, may testify, without being qualified as an expert, as to the effects of marijuana consumption or as to whether a defendant was intoxicated by marijuana. Because, unlike alcohol intoxication, there is no general knowledge as to “the physical or mental effects of marijuana consumption, which vary greatly amongst individuals,” the answer was an unqualified no.

The Supreme Court remanded the case to the district court for further proceedings consistent with its opinion. See: Commonwealth v. Gerhardt, 81 N.E.3d 751 (Mass. 2017). 

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