If you think that DWH — Driving While High — is harmless, you might want to think again.
Two recent studies have concluded that car crashes tend to increase after states legalize marijuana.
The Highway Loss Data Institute found that collision-insurance claims increased by nearly 6% in Colorado, Oregon, and Washington — the first three states to legalize marijuana — compared with neighboring states that hadn't legalized pot.
Researchers at the Insurance Institute for Highway Safety also limited their study to those three states, looking at police-reported accidents, and found a 5.2% increase.
While those somewhat scary statistics should probably guide your thinking on whether you should be driving stoned, you might take a bit of heart from another study. In 2017, the American Journal of Public Health looked at the impact of legalized marijuana on auto fatality rates and found no connection.
Which sounds counterintuitive until you read an explanation like the one the National Transportation Safety Board provided to Congress in 2017. Summarizing several studies, NTSB said, "(A)fter smoking marijuana, subjects … typically drive slower, follow other cars at greater distances, and take fewer risks than when sober. … In contrast, subjects dosed with alcohol typically drive faster, follow at closer distances, and take greater risks."
The consensus thus far, then, is that stoned drivers might be causing more car accidents, but not necessarily worse accidents.
It does seem clear, though, that pot-smoking drivers aren't taking things seriously enough. A 2016 survey of drivers in Colorado and Washington who had used marijuana in the previous month found that 44% of them reported driving while high.
Some states have launched public-education initiatives to discourage driving while high on pot. In Colorado, for instance, the state's Department of Transportation introduced The Cannabis Conversation, a statewide traffic safety campaign.
Perhaps public education campaigns will reduce the numbers of impaired drivers on our roadways, thus making the job of police a bit easier. But the police will still be stuck with the difficult job of determining when, exactly, someone is too stoned to drive.
Unlike the standard breath tests that can determine when someone has drunk too much booze, which are easy to administer and considered generally reliable, the way you measure pot in the system is with a blood draw. This is problematic for two reasons:
Some states have set thresholds on THC blood levels to determine when someone is too high on pot, but defendants have been successful in arguing that they were not impaired.
Researchers are trying to come up with roadside screening technology that will determine when a driver is too impaired on pot. But as it stands, police and prosecutors often have a hard time proving it.
The situation has given rise to a new type of law-enforcement officer called "drug recognition experts." These officers take a two-week course to learn about how specific drugs affect the body and how to examine drivers when they've been stopped.
However, like THC levels in blood, evidence provided to courts by drug recognition experts is subject to serious challenge by defense lawyers. Earlier this year in Massachusetts, in fact, a judge said that a drug recognition expert's evaluation of a man charged with driving under the influence of drugs could not be used.
Still, even though law enforcement needs better tools to detect when you're too high to drive, it's still wise to not get behind the wheel if you're in that condition. You'll be more likely to get in a crash. And if a cop thinks you're too high to be driving, he can still send you to jail.