With marijuana consumption officially legal in Massachusetts, “driving while high” is the biggest concern for police under the recent legalization laws.
Has there been a big increase in incidents of operating under the influence of marijuana in Massachusetts? There is no evidence to suggest legalization causes a spike in impaired driving. A to the degree that marijuana OUI is a problem, it is probably something that has already been with us for some time, prior to marijuana legalization. In fact, people smoked weed and drove before it was legal. Shocking, I know.
Marijuana use is already widespread, even with it illegal in most of the country. About 7.5% of the population have used marijuana in the past month. A legal status change from decriminalization to legalization is unlikely to dramatically increase incidents of “smoking and driving”.
Of course, ensuring public safety on the roads is vitally important. So it is not an irrational concern that legalization could possibly increase the number of people using marijuana and driving.
We will see public campaigns in Massachusetts about the dangers of driving while under the influence of marijuana, as part of the legalization initiative. Drunk driving has decreased over the years because of awareness of the risks and social stigma.
What are the risks of marijuana-impaired drivers?
By all measures, the dangers of driving after using marijuana are significantly less than alcohol. THC impairment is an order of magnitude less dangerous than alcohol impairment. Alcohol has dramatic effects on physical coordination, cognitive ability, and judgment.
THC has a substantially less impact on physical coordination. As far as judgment and perception, the psychoactive effect tends to make people more cautious, as opposed to alcohol which makes people more careless and reckless.
And any direct impact of psychoactive THC varies much more widely in people than alcohol.
But even if there is some measurable public safety risk, as most people would probably assume, a) it already exists and has been out there for decades without causing chaos and destruction on our highways, and b) it is tiny compared to the impact of alcohol and drunk driving.
The bottom line is that any meaningful impact to public safety from possibly impaired marijuana users is unproven and seriously in doubt.
Are marijuana edibles a greater risk for impaired driving?
Maybe. Eating marijuana/THC products, especially if you eat too much, can have a much stronger and longer-lasting psychoactive effect than smoking. Especially for someone who doesn’t know how much to consume.
This was a grave concern for anti-legalization advocates. But there is little to suggest that marijuana edible consumption will spike just because possession became legal this week. Edible purchases on the black market should be unrelated to legalization.
Edibles are widely available at retail in Massachusetts these days. If people haven’t tried them before buying them without knowing how much to take or how they affect them, it could certainly cause some unexpected reactions, and hopefully those people won’t get behind the wheel.
Testing for marijuana impairment
Because of the different physiological effects, there is no agreed-upon chemical measure of THC that establishes impairment. Some states with legal marijuana have enacted a 5ng/ml level blood test standard for THC intoxication, but such measurements are not established by science.
And even if that standard were accepted in Massachusetts, we don’t have forced or mandated blood extraction. In drunk driving law, the solution to measuring alcohol consumption and intoxication is the “breathalyzer”. Breath test machines operate by calculating breath alcohol (BrAC) from deep in the lungs and applying a formula that is roughly equivalent to blood alcohol (BAC). But no such breathalyzer exists to measure THC from a breath sample.
The only impairment testing for marijuana or drugs that police have at their disposal is an evaluation by a trained drug recognition expert or DRE. A DRE has a checklist of tests of physiological measurements and responses that establish a likelihood of being under the influence of drugs, and exactly what drugs those might be.
As this report notes, there are over 100 certified DRE police officers, but not every department has one. And similar to a breath test, a DRE evaluation happens back at the police station, so the drug evaluation happens after a person is arrested. The testing itself takes about an hour. But the officer has to have probable cause for an OUI arrest before any drug use and impairment is evaluated by the DRE.
Much of the science of DREs is questionable at best, and not always admissible in court. DRE’s use the “finger to nose test” as well as the horizontal gaze nystagmus (HGN) eye test. Both of these tests are commonly used by police officers in drunk driving cases. And both have been determined to be inadmissible in Massachusetts courts in drunk driving cases because they are scientifically unproven.
And if you are arrested, you are able to legally decline the DRE evaluation, without it impacting your court case or your driver’s license.
What is a better solution for evidence in OUI drugs?
If scientific testing doesn’t work, what can the police do to prove impairment and driving if they believe it’s a big problem?
One solution is more video evidence of the police stop could be used for legal evidence of impaired driving. Noted attorney and legalization advocate Richard Evans supports this approach.
Both dashcams for vehicle stops and body cams for police interaction would capture whatever poor driving led to the stop and the interaction with the officer that lead him to believe the driver was high. A judge or jury could view how the defendant actually appeared at the time, and make their own determination as to whether the person’s ability to drive a vehicle safely appeared to be compromised.
Unfortunately, neither dashcams nor bodycams are widely used by Massachusetts police departments. Boston has a pilot program going on now. But this kind of transparency would help address OUI drug case evidence as well as many other questions of police evidence and citizen interactions.
Marijuana legalization is a fact in Massachusetts, so we will have to adapt to a new world of laws and standards for both our citizen’s freedom and public safety.