Driving While High Study Could Foreshadow MA's Future

SALEM, MA — Massachusetts officials are likely to pay close attention to an AAA study released Thursday. The study showed the percentage of Washington state drivers involved in fatal crashes who tested positive for marijuana doubled in the five years after the state legalized pot in 2012.

Nearly 9 percent of drivers involved in fatal crashes in Washington tested positive for THC, the main ingredient in cannabis, between 2008 and 2012 — the five-year period before the drug was legalized in Washington. According to the study, that percentage rose to 18% between 2013 and 2017. The study did not try to determine if marijuana played a role in those crashes.

In Massachusetts, where cannabis sales started in late 2018, it's too soon to measure the impact of recreational marijuana on highway safety. States that have legalized the drug have struggled to set and enforce impaired driving rules. That's because no data reliably shows what level of THC impairs driving, the chemical’s effects vary by user, and THC testing often can’t be performed until hours after a crash, AAA said.

In Massachusetts, impaired driving laws and penalties for cannabis users mirror those of operating under the influence of alcohol.

"The results are concerning because the analysis suggests legalization of recreational marijuana may contribute to an increase in the rate of THC-positive drivers involved in fatal crashes," said Fran Mayko, AAA Northeast spokeswoman. "AAA’s message is if you’ve used marijuana, don’t drive...And if you plan to drive, don’t use marijuana."