Gov. Charlie Baker joined law enforcement officers, highway safety advocates and marijuana regulators Thursday to remind people who "plan to have a really good time" this St. Patrick's Day weekend that "if you feel different, you drive different" and should find alternative transportation.

Representatives from municipal and state police joined Baker and members of the Cannabis Control Commission to launch a new campaign aimed at educating cannabis users of the dangers of impaired driving, and to remind people to safely enjoy whichever substance they might consume. He also touted a bill he filed earlier this year to adopt recommendations of a commission that studied ways to deal with operating under the influence.

"Mostly we do a pretty good job, because of many of the people behind me and many of their colleagues who are out on our highways and streets, of keeping our streets safe," Baker said. "But the simple truth of the matter is there is a lot of evidence and plenty of data to support that after years and years and years of seeing a regular and continued decline in traffic accidents, we have seen those numbers level off and in some cases and some areas actually go up."

After alcohol, marijuana was the most prevalent drug found in the systems of drivers involved in fatal crashes in Massachusetts between 2013 and 2017, the governor's office said. The bill (H 71) he filed in January touches upon detection of impaired drivers, interaction between police officers and drivers who are thought to be impaired, and how cases involving suspected impaired drivers are handled in the state's courts.

Last year, a Department of Public Health study found that nearly 35 percent of adults who reported using marijuana in the past 30 days also reported driving under the influence of marijuana. DPH said baseline data suggest that about 7 percent of all adults drove under the influence of marijuana in the past 30 days and that about 12 percent of all adults rode with a driver who was under the influence of marijuana.

Baker's bill is based on 19 recommendations from the Special Commission on Operating Under the Influence and Impaired Driving. If the Legislature adopts the recommendations, a driver suspected of driving under the influence of marijuana who refuses to take a chemical test for impairment would lose their license for at least six months, the same penalty as for suspected drunken drivers who refuse to take a breathalyzer test.

Also among the group's recommendations is a proposal that the Legislature adopt a statute authorizing state courts to take "judicial notice" that ingesting the active component in marijuana, THC, "impairs motor function, reaction time, tracking, cognitive attention, decision-making, judgment, perception, peripheral vision, impulse control, and memory." The group also suggested that lawmakers amend the open-container law so it can apply to marijuana, meaning drivers could not have loose or unsealed packages of marijuana in an area of the car accessible to the driver.

The special commission, which was created as part of the 2017 law that also established the Cannabis Control Commission, also suggests amending the existing operating under the influence law so that, in court, the state would have to prove only that the driver was impaired to obtain a conviction.

"This bill is a bold legislative initiative comprised of common-sense language that will strengthen the state's impaired driving laws," Assistant Undersecretary for Law Enforcement and Criminal Justice Angela Davis said.

Marijuana became legal for adults to use and grow in December 2016 and since November 2018 retail stores have made the drug more available to consumers around the state. State Police Lt. Col. Chris Mason said troopers have "seen a lot of compliance with the Cannabis Control Commission regulations relative to the storage and transport of marijuana," but have also seen a rise in impairment generally.

"Not all attributed to cannabis or alcohol. Remember, we have a significant opioid issue within the commonwealth," he said. "Another facet of this, I know it's not the topic for today, is impairment through the use of opioids and we've seen that to be a significant issue within the commonwealth."

CCC Commissioner Britte McBride said impaired driving is not a new problem, but that legalization of marijuana means the state has "an enhanced obligation to address the issue of impairment anew."

"Let me tell you what this bill doesn't do because a lot has been made of what the bill does," she said. "To be clear, this bill does not take away personal choice to consume cannabis nor does it re-stigmatize the consumption of cannabis unless that consumption of cannabis is coupled with operating a vehicle while impaired. In that case, yes, this bill does stigmatize operating under the influence; and it should, just as we do with alcohol."

Though the bill would not require marijuana businesses to do anything they are not already required to do under CCC regulations, Keith Cooper, the president of the Cannabis Dispensary Association, said his organization's member companies have agreed to provide educational flyers about the dangers of driving under the influence of marijuana with each purchase.

The commission's recommendations, and Baker's bill, also call for the Municipal Police Training Committee to expand training of drug recognition experts -- the commission said the state's municipal police forces should have at least 351 DREs total, as well as other DREs at the State Police -- and for the state's court system to allow DREs to testify as expert witnesses.

Baker did not make a strong push Thursday to have the Legislature take up his bill quickly and said he expects the bill will get a hearing "sometime later this year" and said he is encouraged by the feedback he's heard from lawmakers.