The state's highest court is ruling that police can arrest a person for drugged driving based on an officer's observations alone.
The Supreme Judicial Court ruling came in the case of a man arrested for alleged drugged driving in Brighton in 2015.
The man was acquitted of drugged driving at trial, but later challenged the legality of the arrest because narcotics and a handgun were found in his car.
The high court says the arrest was constitutional, as it was based on the observations of the police officer.
Legal experts say that it is an important decision because police don't have a reliable test for high drivers as they do for drunk ones.