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A Sober Look at Driving High

Operating a car on marijuana might not be as dangerous as drunk driving, but you still shouldn’t do it.

Screenshot of Harold & Kumar Go to White Castle

With a number of American states pondering marijuana legalization and a new Canadian prime minister openly supportive of legitimizing pot in every sense, 2016 could be a big year for weed. But as legalization creeps forward, so do public awareness of and concern about the effects that opening up the weed market could have on society. One of the biggest emerging issues—one that’ll likely have an impact on some upcoming legalization debates—is stoned driving. For the past several years, lawmakers have struggled to figure out how to monitor for, regulate, and punish driving while under the influence of marijuana. But a more important and fundamental battle may involve convincing weed users and advocates that stoned driving is something they should care about—and co-opting pot people to help change cultural norms around weed and driving.

To date most official discussion on stoned driving has revolved around the struggle to detect it. We’ve long had effective tests (e.g., the Breathalyzer) for blood alcohol content that give us a sense of whether someone is impaired by booze. Some people are less impaired than others at the same BAC, but at our legal cutoff of 0.08 percent, it’s fair to say that everyone at that level is under the influence, posing an unnecessary risk to others, even if they’re not all equally sloppy drunk. But when it comes to marijuana, we lack both the proper tests to analyze a driver on-site—and the ability to discern if a particular chemical signal corresponds to impairment.

The best means we have now of testing for weed use (outside of field sobriety tests, which are time-consuming and sometimes ineffective) is a blood test—which can’t be done on the road. Cops have even field-tested saliva tests. But while these tests work well in labs, on the road they tend to yield false results far too often to be of use. And even if saliva tests develop to the point where they can be used by cops on the road, these tests don’t actually tell us whether a person is inebriated. They measure the level of THC, the psychoactive ingredient in weed, in a person’s bloodstream. But chronic users (not just serious tokers, but more likely medical users) often retain traces of THC in their system for days, weeks, even (in some cases) years after smoking—long after the drug’s effects have worn off. This means that states, which today either follow a zero-tolerance policy—dubbing anyone with any THC in them “under the influence”—or use five nanograms per milliliter of blood as a 0.08 percent BAC equivalent, may wind up arresting a ton of legitimate, sober weed users.

Yet figuring out how to make a weed Breathalyzer, chart usage versus impairment, and adjust laws to accommodate chronic users may not be the most important step we can take to address the issue of stoned driving and road safety in the era of legalization. Instead we may need to start by just convincing weed users that stoned driving should be avoided.

Cheech & Chong. Image via

If you watch stoner movies, from Cheech & Chong’s 1978 feature Up in Smoke to, well, 2013’s Cheech & Chong’s Animated Movie, you’ll notice that no one ever seems to worry about driving while high. Hell, toasted cruising is the central, heroic conceit of the quintessential modern stoner movie, 2004’s Harold & Kumar Go to White Castle. The problem is that it’s not just a movie thing: In polls from last year, about 70 percent of Americans thought that driving while impaired by weed wasn’t really a problem; only 29 percent thought it was a serious problem. Some people, like those with chronic pain or anxiety, even argue that weed makes them better drivers. These folks like to back up their claims with mythic studies no one can ever quite pin down that supposedly prove that driving stoned is as safe as, if not safer than, driving sober. This attitude doesn’t seem to be inspiring more pot users to hit the road high in legalized states. But even if stoned driving rates aren’t spiking massively now, this pro-stone-driving, or at best stoned-driving-neutral, cultural norm seriously abets potentially dangerous behavior on the road.

It’s worth noting that the studies people claim show stoned driving to be as safe as (if not safer than) sober driving don’t exist. In October, an essay on the site Aeon did a brilliant job of tracking the myth of these studies back into the rhetorical needs of American weed culture, which have distorted the findings of real studies in a game of self-soothing telephone. But even if there is no golden ticket justifying stoned driving, weed lovers have a ton of other studies to fall back on to excuse their habit, arguing that driving while high is, if not totally neutral, basically harmless.

When it comes to drunk driving, a host of robust and well-trusted studies show how drastically an elevated BAC can impact road safety, making an individual 9 to 20 times more likely to get into a fatal crash (depending on demographic). Yet early critical research on pot was not nearly as rigorous—a shortcoming that may have poisoned the well of trust and acceptance for critical findings. Meanwhile, more recent studies seem to indicate that, while weed does affect reaction time, peripheral vision, multitasking, and other functions, stoned folks tend to be better at recognizing and correcting for their impairments than drunk folks. And whereas drunk folk are always impaired, chronic stoners can build up resistance to the stupefying effects of weed. Some studies argue that ultimately stoned driving doesn’t significantly increase the risk of getting into or causing a fatal crash. Some go so far as to suggest that medical or full weed legalization can decrease crashes—maybe because people who’d otherwise drink wind up under weed’s less impairing influence, or even stay at home to smoke instead of going out to a bar and driving home.

Image via Flickr user Rafael Castillo

Yet even if states with legalized weed use aren’t seeing an increase in fatal pot-related car crashes, that doesn’t mean it’s safe to drive high. Stable or decreasing crash rates in such pot friendly states could correspond to general improvements in car and road safety. It’s possible to argue that crash numbers might have been even lower with fewer high drivers on the road.

In direct contrast to the rosy picture some paint of stoned driving, researchers have argued that the compensations drivers make when high (slowing down, looking around) don’t actually help them to overcome impairments when things go south on the road. And impairment isn’t a quantum state; the higher you are, the worse impairment gets—especially for novice users. Despite variations from person to person, studies suggest that crossing a certain threshold of THC in the blood correlates (on average) to a 2.2-to-6.6-fold increase in crash risk. The risks get much higher when people consume both booze and pot; that’s an increase in risk by as much as 14-fold. Granted, some have argued that these risks are overblown—that a mild high is still no more dangerous than driving on a solid antihistamine or that cognitive and experimental research reach very different conclusions about risk. But the fact remains that when you drive stoned you are impaired and you may not be able to correct for that. And while that may not drastically increase your risk of getting into a crash, it is ultimately an irresponsible act—getting into a giant metal block and hurtling down the road without the total control needed to minimize your chance of damaging not just yourself, but others who didn’t sign on to the risks of your impairment.

Even if we can convince people that there’s risk in driving high—that it’s irresponsible and immoral—we still need to figure out how to get them to care about or act on that knowledge. We’ve seen this struggle play out historically with alcohol. Although drunk driving was a crime in parts of the United States as far back as 1910, and a serious public health concern for experts by the 1920s, most people didn’t think too much of driving while inebriated. Up until the 1980s it was recognized as a risk and perhaps an ethically bad thing to do. Yet people often turned a blind eye to drunk driving as a universal fault in humans, or even an inevitable right of passage for kids. It didn’t help that, up until the mid-20th century, detecting inebriation was a subjective art. And even after that, standards for measuring alcohol consumption were not as solid and accepted as they are now.

Mothers Against Drunk Driving billboard. Image via

We turned those attitudes around in the ’80s thanks to the efforts of groups like Mothers Against Drunk Driving, which aggressively publicized drunk driving’s horror stories and backed tons of laws and programs making it a much more serious crime. Unfortunately, this process may not work as well for high driving as it did for drunk driving, considering that the scale and horrors of the problem seem to be significantly lower. Any attempt to trumpet the pain and blood of high driving may also be read by a skeptical pro-weed population, used to scare tactics and misinformation about the gentle herb, as misrepresentative propaganda. And given how little we know about usage-versus-impairment, at this point any reporting aggressively linking weed to terrible wrecks would probably be problematic and overblown.

Rather than convincing people that high driving is as dangerous as drunk driving or touting the notion that legalization will fill the roads with weaving idiots, we need to convince pro-pot people that there is a real risk in high driving—and that they need to promote awareness of it through existing channels. A fact-based approach (using the same avenues discussed in the above-mentioned Aeon essay) dispelling the safer-than-sober myth could change our cultural norms, communicating exactly what weed does to your driving ability, how you cannot fully control for it, and why, while it may not massively increase your risk, it’s still not cool. We can disseminate the knowledge that, much like you would wait a few hours to drive after taking a drink, you should wait a few hours after a toke to get behind the wheel as well.

If early on in pot’s legal proliferation we can establish a prevailing cultural norm of designated drivers, we can minimize the number of high drivers and risks they create. That would go a lot further in making the roads safer than developing “THC Breathalyzers” or the like. Using that space—linking visibly improved safety with the perception of high driving as a rarity—we could perhaps have a less hurried discussion about measuring pot impairment. Ideally we’d be able to set up a means of field sobriety detection and give those flagged a chance to appeal based on some measure of their resting THC levels. But developing acceptance that high driving is a real risk is a prerequisite for any constructive conversations toward that ideal.

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