Driving While Stoned: The Penalties and Gray Area in Marijuana Law

smoking a joint
Marijuana users should know the penalties they could face if they get behind the wheel. | Pedro Pardo/AFP/Getty Images

As of November 2017, some 29 states had legalized marijuana for medicinal use. By 2018, eight of those states will allow the recreational use of pot, too. Add in the millions of Americans who smoke weed illegally and you have a small army of stoned individuals hanging out in public at all hours.

At your local bar or drum circle, that’s not a problem. On the other hand, when driving your kids home from school, you don’t want to run into a guy who just took a round of bong hits. Likewise, marijuana users need to know the risks they face if they get behind the wheel high. State penalties for stoned driving are mostly as harsh as they are for drunk driving. Nothing kills a buzz like 120 days without your license or $1,500 in fines.

However, there is no “pot breathalyzer” yet, and officers usually need special training necessary to otherwise judge intoxication via weed. Overall, confusion reigns, and the arrests of people who hadn’t used marijuana before driving have made the situation worse. Here’s what everyone needs to know about pot and driving, down to the gray areas in the law.

1. The risks of driving while high

While there is agreement among scientists that driving under the influence of marijuana creates a more dangerous situation, there is no consensus of just how much danger. A 2016 paper from the Society for the Study of Addiction found the increase in crash risk “of low to medium magnitude.” That assessment scaled back some of the hyperventilating following the legalization of recreational marijuana.

Even government agencies have a hard time saying how marijuana affects motorists. In February 2015, NHTSA released a study on alcohol and drug use among drivers. Once again, they found clear evidence of impairment among drunk drivers, down to the degree. Drug users proved harder to gauge. “At the current time, specific drug concentration levels cannot be reliably equated with a specific degree of driver impairment,” the report concluded.

2. Smoking versus edibles

marijuana brownie samples
It’s hard to tell how impaired edibles will make a person. | Frederic J. Brown/AFP/Getty Images

In March 2017, a paper from Oxford’s Journal of Analytical Toxicology revealed some interesting findings about edible pot. (Edibles include candies, brownies, cookies, and other foods with THC infusions.) For starters, “impairment on cognitive performance tasks was only observed at the higher doses,” researchers found. Only people who had consumed a great deal showed it. On the other hand, the quantity of the drug found in user’s blood was low. In short, it’s much harder to accurately tell how high someone is with current testing methods.

3. The current legal limit

worker displays various types of marijuana
THC stays in the body for days. | David McNew/Getty Images

While this figure will be hard for most people to gauge, the legal limit set by many states is 5 nanograms of THC per milliliter of blood. However, this limit has proven problematic for law enforcement agencies. Just as edible pot users may not appear to be high, regular marijuana users may exceed that limit even though they did not smoke any weed before driving.

A 2014 Colorado case showed how that could happen. While on her way home one night, Abby McLean stopped at a DUI checkpoint and was arrested on suspicion of driving while high. At the police station, blood tests showed she had five times the legal limit. Here’s the thing: She hadn’t smoked at all. THC stays in your body’s fat cells for days — sometimes longer than a week. Current testing levels don’t account for that.

4. How ‘legal’ states have adapted

Blue police light on top of a police car at night
Police look for signs of impairment. | Getty Images

With pot already legal in many states and California on the way, law enforcement agencies are scrambling to get their system in place or up to date. In Colorado, the 5 nanogram limit remains in place. However, the Department of Transportation allows leeway to cops who arrest drivers “on observed impairment.” That phrase appears to be a reference to hard-to-detect edibles. Even if you test below the limit, officers may not let you drive away.

5. Further testing at police stations

police officer
A drug recognition expert might conduct more tests at the police station. | Andrew Burton/Getty Images

In cases where cops have suspicion a driver is high but cannot prove it, they may call in a drug recognition expert (DRE). Though it only takes two weeks of training to become a DRE, many departments may only have one on the job every shift. (Some departments may have none on staff.) These experts will run drivers through a battery of tests at the station to make a determination of their intoxication.

6. The California conundrum

palm trees against a sunset in California
California will face challenges with the legalization of recreational marijuana. | lunamarina/iStock/Getty Images

If you haven’t heard, recreational marijuana use is legal in America’s largest state as of January 2018. Yet California is far from ready to deal with it. According to Rich Glenn of the Santa Clara Sheriff’s Office, judgment calls will be the norm. “The challenge for law enforcement is that a lot of it is going to be based on initial driving indicator tests and then field sobriety tests,” he told San Jose Mercury News. “But there is no kind of concrete scientific way to measure it.” In other words, court cases may soon become the norm.

7. Regular vs. occasional users

person with marijuana-shaped sunglasses
Regular users could have high THC levels for days. | Nelson Almeida/AFP/Getty Images

As learned in the Abby McLean case in Colorado, regular pot users will need to take extra care when taking to the road. High THC levels may still appear in the blood hour or days after consumption. On the other hand, the occasional user may be able to avoid an arrest if police do not detect impairment through field testing. In McLean’s case, it took a trial case and a lesser plea for her to avoid a conviction. Low-income drivers would face the usual hardships and an elevated risk if legal help became necessary.

8. The easiest work-around

A closeup view of marijuana
Your best bet is not to drive if you might have marijuana in your system. | Bruce Bennett/Getty Images

Though driving with marijuana in your system may be less dangerous than driving drunk, any impaired driver presents risks to themselves and others. The easiest way to avoid danger and trouble with the law is refusing to drive after consuming weed. A ride is only a few clicks on a smartphone away these days. Compared to a DUI rap or the cost of hiring a lawyer to defend you, that’s small change. As for the deficiencies in testing for THC, states need to update and correct their system. Otherwise, expect a glut of cases in traffic court.

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