Now that marijuana has been legalized in Massachusetts for those over 21, I am seeing more and more people being charged with operating a motor vehicle while under the influence of marijuana.  Questions I am frequently asked include: “how can they prove I was under the influence of marijuana?” and “what type of evidence will they use in my trial for operating under the influence of drugs (marijuana)?”

The Supreme Judicial Court recently offered guidance to the trial courts regarding the admissibility and use of the results of so-called Standardized Field Sobriety Tests at trial, as well as promulgating a model jury instruction to be used in OUI-marijuana trials.

The Standardized Field Sobriety Tests promulgated by the National Highway Traffic Safety Administration consist of a battery of three tests that, when administered properly, are decent predictors of impairment by alcohol.[1]  The tests are the Horizontal Gaze Nystagmus Test (HGN), the One-Legged Stand Test (OLS), and the 9-Step Walk and Turn Test (WAT).  In Massachusetts, the courts have long held that only an expert can testify as to the results of the HGN test, and since most police officers are not qualified as experts on that issue, HGN test results are very rarely used at OUI trials.  Interestingly, the NHTSA itself admits that if only the OLS and WAT are used, without the HGN, then the SFST are much less reliable at predicting alcohol impairment.  But that’s an issue for another blog.

With respect to the crime of operating under the influence of marijuana, “there is as yet no scientific agreement on whether, and, if so, to what extent, these types of tests are indicative of marijuana intoxication. The research on the efficacy of [S]FSTs to measure marijuana impairment has produced highly disparate results.”  Commonwealth v. Gerhardt, 477 Mass. 775, 776 (2017).

In Gerhardt, a recent case involving an allegation of operating a motor vehicle while under the influence of marijuana, a Worcester District Court trial judge certified 4 questions to be answered by the Supreme Judicial Court of Massachusetts.  The 4 questions were these, viz.:

  1. Whether police officers may testify to the administration and results of SFSTs in prosecutions for operating under the influence of marijuana as they do in operating under the influence of alcohol prosecutions?
  2. Are the effects of marijuana consumption sufficiently within the common knowledge and experience of a lay person, such that a non-expert witness may offer opinion evidence whether a person is ‘high’ on marijuana?
  3. May a police officer, who has not been qualified as an expert witness, testify to the effects of marijuana on a person such as bloodshot eyes, lack of coordination and/or balance, reaction times, slow speech, paranoia, or relaxed responses?
  4. May a juror rely on their own experience and common sense about the effects of marijuana as they may do in an operating under the influence of alcohol prosecution?”

Here is how the SJC responded:[2]

  1. Whereas a police officer may offer testimony in an OUI-liquor case that the driver took field sobriety “tests,” in marijuana impairment cases, a police officer must refer to “roadside assessments,” so as not to lend an air of scientific validity that may not be warranted.  An officer also may not testify that a defendant “passed” or “failed” any of the assessments, and may not testify that the defendant’s performance of the assessments indicates impairment.
  2. “Because the effects of marijuana may vary greatly from one individual to another, and those effects are as yet not commonly known, neither a police officer nor a lay witness who has not been qualified as an expert may offer an opinion as to whether a driver was under the influence of marijuana.” That is, a police officer or other non-expert cannot testify that the defendant was “high” on marijuana.
  3. While a police officer may testify to what he or she observes of the defendant driver – such as blood shot eyes, drowsiness, and lack of coordination, a police officer is not permitted to offer an opinion that these characteristics mean that the driver is under the influence of marijuana.
  4. The SJC apparently thought this could have been answered by the trial judge, and it answered tersely in the affirmative that, “[j]urors are permitted to utilize their common sense in assessing trial evidence.”

So, that’s the state of the law as of today.  A police officer may ask a driver suspected of being high on marijuana to perform SFSTs, and may testify about his or her observations of the driver’s performance.  However, at trial the officer may not refer to “tests,” or opine that the driver failed, or state that the driver was high on marijuana.  As a result of earlier decisions, a non-expert police officer also may not testify as to performance on the HGN.

The Gerhardt case will probably lead to police departments and the State Police sending more of their offices to training to become “drug recognition experts,” or DREs.  We shall see.

I have also recently seen several cases where individuals have been charged with driving with an open container of marijuana in their vehicle.  I’m not sure what a “closed container” of marijuana would consist of, since, to my knowledge, marijuana does not come in a sealed package.  I will write on that topic as I learn more.  Please drive safely, and do not drive while impaired by any substance.

Attorney Kevin D. Quinlan

The Law Offices of Kevin D. Quinlan

2 South Main Street, Suite 201

P.O. Box 248

Uxbridge, MA  01569

(508) 723-6384



[1] “These tests were developed specifically to measure alcohol consumption, and there is wide-spread scientific agreement on the existence of a strong correlation between unsatisfactory performance and a blood alcohol level of at least .08%.”  477 Mass. 776.

[2] Because the Massachusetts SJC is not an Article III court, it does not require a “case or controversy,” and is able to issue “advisory opinions.”

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