When Massachusetts voters in 2016 approved recreational marijuana, the measure required investigation into the impact of weed-impaired driving. But neither the ballot question nor the final version of the bill sets limits on marijuana consumption, intoxication and a person’s ability to drive a car.

The law did set up the special commission, which got to work only a month before recreational sales were scheduled to begin.

The commission, which includes lawyers, law enforcement, professors and government officials, is charged with researching how Massachusetts can address drug-impaired driving and making recommendations to the Legislature no later than January.

The commission held its first meeting in June, when members spent time discussing the value of drug-recognition officers.

The panel is mulling expansion of the drug-recognition program throughout the state as one approach to policing impairment, though civil rights advocates are against it.

Critics say the drug-recognition analysis are overly subjective and lack supporting scientific research.

“There’s also a concern with specialized policing units and how much racial bias plays into their actions,” said Rahsaan Hall, director of racial justice for the American Civil Liberties Union of Massachusetts. Studies have shown that people of color are more likely than white people to be stopped by police, put in handcuffs, pepper-sprayed, pushed to the ground or shot by the police.

State Rep. William “Smitty” Pignatelli, D-Lenox, said he understands people want an answer to the question on impaired driving enforcement but said the Legislature is holding off on making decisions regarding drugged driving until the commission reports its findings.

“People are generally concerned about this. There’s a police training program to tell what drugs a person is under, but right now, I don’t think there is a perfect science to it,” said Pignatelli, who expressed interest in creating a blood-weed standard but isn’t sure how one could be accurately administered.

“If you smoke marijuana two weeks ago, technically, it’s still in your system,” he said. “Does that mean you’re too impaired to drive? What is the equivalence of a blood-alcohol test?”