Marijuana Field Test Are Ruled Unreliable By The Courts


The Massachusetts Supreme Judicial Court has come to the ruling that field sobriety tests that are typically used in drunk driving incidents cannot be used as solid evidence to prove a driver was operating under the influence of marijuana.

Because both the physical and cognitive effects of weed differ from person to person, higher power deemed that a police officer does not have the right to make the distinction whether or not a motorist is “high” upon testing the subject.

“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,” the court explained.

Unlike alcohol, police are not equipped to determine whether or not the driver is definitively high.

While police officers cannot tell whether or not the subject was under the influence of marijuana based on traditional sobriety tests or their own formulated opinion, they can, however, testify to certain “roadside assessments”. These include observations of typical symptoms such as bloodshot eyes, drowsiness, a strong odor of marijuana, slow or erratic driving and lack of coordination.

The court added that it will be up to the jury to determine whether or not the individual in question was under the influence of weed after reviewing the officer’s roadside assessments.

“Jurors are permitted to utilize their common sense in assessing trial evidence,” the court explained.


Despite recreational cannabis now being legal in the state of Massachusetts, driving under the influence of cannabis remains illegal.

Yet, Massachusetts justices stated there is no reliable scientific test for marijuana impairment at this current time, making it challenging to assess on a case-by-case basis.

Martin Healey, the Chief Legal Counsel for the Massachusetts Bar Association also admitted as much and ceded that the court’s decision makes it increasingly arduous to make a definitive ruling on a subject’s level of impairment.

“[the decison] does continue to tie the Commonwealth’s hands and police officers’ hands in evaluating and testifying in court regarding someone operating under the influence of marijuana,” Healey said to WBZ NewsRadio 1030.


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