How high is too high?

Police say they’re hamstrung in testing drivers for marijuana

Jack Sullivan

WHEN PROHIBITION ENDED IN 1933, law enforcement officials found themselves in an awkward position. They knew driving drunk was a problem, but they didn’t know how to police it. How do you measure drunkenness?

In 1931, an Indiana University professor invented the Drunkometer, in which a person would blow into a balloon and then that air would be released into a potassium solution. The solution would change colors if there was alcohol present. The more it changed colors, the more alcohol there was in the person’s breath. But that didn’t measure whether a person was drunk or how much alcohol was in their system.

Over the years, police developed field sobriety tests and then Breathalyzers came along in the 1960s.

The level of intoxication for driving in Massachusetts was initially set a blood alcohol content of  .15 and over time ratcheted down to .10 and now the current the legal limit of .08
Now, as marijuana fans push for full legalization, the same problem is surfacing again.

Law enforcement officials say there is no way to accurately determine whether someone who is driving is high and there is no standard for determining how high is too high.

Part of the problem is the only tests available for marijuana’s presence – either through urine, blood, or swab – only detect the amount of the drug in the system, not when a person used it. Unlike alcohol, which dissipates in the system within hours, making a breath test an effective measure, marijuana can stay in the blood for days, even weeks.

“It’s a big issue,” said Norwood Police Chief William Brooks, president of the Massachusetts Chiefs of Police Association. “We don’t have the same ability to test a person’s breath the way we can for alcohol. Marijuana stays in the system much longer, so it’s difficult to prove when they actually smoked it. Someone could have it in their system but it’s from days ago and they may not be impaired.”

Police officer conducts field sobriety test in Oregon.

There’s also some evidence that being high on marijuana has a different effect than alcohol. In 1993, researchers at the National Highway Transportation and Safety Administration had test subjects smoke marijuana and then get behind the wheel of a car on a highway, with officials following them.

They concluded the buzzed drivers had a handle on things.

“Drivers under the influence of marijuana retain insight into their performance and will compensate where they can, for example, by slowing down or increasing effort,” the report concludes. “As a consequence, THC’s adverse effects on driving performance appear relatively small.”

Similarly, a 2010 study by Yale University researchers published by the National Center for Biotechnology Information, part of the National Institutes of Health, found those who smoke marijuana had a better grasp on driving than those who drank or used alcohol and marijuana at the same time.

“Surprisingly, given the alarming results of cognitive studies, most marijuana-intoxicated drivers show only modest impairments on actual road tests,” said the study. “Experienced smokers who drive on a set course show almost no functional impairment under the influence of marijuana, except when it is combined with alcohol.”

For some who smoke pot on a daily basis, those findings come as no surprise.

“I honestly don’t think it affects me at all,” said Luke, an 18-year-old high school senior in the suburbs. Luke, who said he smokes every few days, said the police don’t bother with small-time users like him anyway. “I’ve been caught by the police before. They took my stuff, threw the weed on the ground, and took my grinder and bowl with them.”

But those in law enforcement and in the hospital room disagree about the effect of marijuana on those behind the wheel and say they need a measure that will aid in keeping pot-intoxicated drivers off the roads.

A California emergency room doctor who is also a reserve sheriff in San Francisco said he has developed a Breathalyzer-like device to gauge marijuana levels and is set to field test it, with a goal of getting it into police department hands by the end of this year or the beginning of next.

“It only stays in your breath about two hours, whereas in saliva, blood, and urine it can stay positive in your blood for weeks,” said Dr. Mike Lynn, who developed the idea after watching the results of impaired drivers in his emergency rooms. “We will measure breath, not blood. Right now, no one knows when the person last smoked.”

The prototype that Lynn has developed, which he declines to talk about too specifically for fear of revealing proprietary information, would measure both alcohol and marijuana levels in the breath so police would not have to use two separate devices.

What it won’t do, however, is measure THC, the primary chemical in marijuana that produces a high if someone ingests the drug through increasingly popular edibles. In Colorado, the first state to legalize the recreational use and commercial sale of marijuana, edibles accounted for 45 percent of sales in the first year of the law.

“The first generation will not measure [edibles], but we will be able to measure that down the road,” said Lynn, whose company, called Hound Labs, is one of several worldwide trying to create a usable device.

A problem for police right now is the price of chemical tests to detect marijuana, which can run $200 to $400 each, a prohibitive cost for tight department budgets. Breathalyzers cost anywhere from $100 to $400. Lynn is expecting his device to sell for about $400 and, since he claims it will measure both pot and booze, departments will only have to buy one kind and officers will only have to carry one device.

“It doesn’t do much good to have a Breathalyzer that nobody can afford to buy,” he said.

A stumbling block, however, is the lack of standards for what constitutes driving under the influence of marijuana, like the .08 level for alcohol. A dozen states have a zero tolerance for any detectable level of marijuana found in drivers, according to the Governors Highway Safety Association.

Five states have “per se” laws regarding the amount of marijuana someone can have in their system before being considered legally impaired, ranging from 1 nanogram per milliliter of blood to 5 nanograms per milliliter. Massachusetts has no current standard.

“Because there is no device, you need to rely on the other aspects of the field sobriety test that tests cognitive abilities,” said Sam Cole, communications director for the Traffic Safety division of the Colorado Department of Transportation. “The officer may be able to spot marijuana use by smell or odor. Very often it is hard to hide the odor of marijuana, so if there is a noticeable smell, that can trigger probable cause.”

In Colorado in 2014, prior to marijuana becoming legal, driving under the influence of pot constituted roughly 12 percent of the impaired driving convictions. Last year, after it became legal to buy and use, that number went up to 15 percent.

But Cole said that percentage doesn’t include people who were arrested whose case could not be proven because they refused a blood test.

“You are relying on an officer’s skill to identify based on the cognitive ability of the driver,” said Cole. “The one thing Colorado is doing is training more and more drug recognition officers.”

Field tests, though, can be subjective. The field sobriety tests used for marijuana are the same ones used for alcohol. According to the National highway Traffic Safety Administration, the three most commonly used field sobriety tests have wide margins of inaccuracies in predicting someone’s impairment, ranging from 65 percent of proper classification to 77 percent.

Even if the breath analyzer by Hound Labs proves effective, there are no standards for what level will constitute someone being impaired by marijuana. The per se levels set by some states are based on blood samples and would not translate to breath detection. And because there has never been a viable test, standards through research would have to be developed to determine an impairment level.

Brooks said he hopes the breath detector for marijuana can be developed because it would be another tool for police to get impaired drivers off the road. Even so, he said, the decriminalization of marijuana in Massachusetts in 2008 has increased the number of impaired drivers. Legalizing the drug would multiply that exponentially, he said.

“I would just hope people would understand that if they pass this, police will be powerless to do anything about [impaired driving,]” he said. “We’re really at a crossroads here, whether voters are going to decide to add another drug that is going to affect kids and get them thinking it’s okay to smoke and drive.”