You Okay to Drive?

You know what a breathalyzer is. Every adult has some idea of how one works and what safe alcohol levels are. But do you know what a safe level of cannabis in your system is? Do you know how it’s measured? And what’s the equivalent of a breathalyzer for cannabis? The answer, right now, is that there really isn’t one.

This is a topic of concern for two groups.

First, law enforcement. A sobriety test that’s subjective doesn’t mix well with innocent until proven guilty. A concrete, measurable and unambiguous test makes the job of law enforcement – and subsequent court proceedings – immeasurably easier.

Second, consumers. Yes, if you’re a cannabis user, this is important to you too. Experienced drinkers – and even inexperienced ones – know their personal math of drinking. A shot, glass of wine or glass of beer contain around the same amount of alcohol (the craft beer revolution has complicated this, but only slightly). A drinker has at some point cross referenced their body weight and their number of drinks, and using the legal limit, figured out how many drinks they can safely have. For cannabis, there’s no comparable system yet.

Self reporting, or doing your own field sobriety test, is impractical. I’ve seen drunks weave the full width of a sidewalk and insist they just walked a straight line. Trying to self-assess your cannabis intoxication seems likely to be almost as unreliable. So how does an honest consumer, who doesn’t want to be a danger to himself or others, know where the borderlines are between safety and danger?

One important component is already built into current medical laws and proposed tax and regulate legislation – clear labeling and consistent amounts. So that, like the equal impact of a shot and a beer, edibles, vape and other ways of consuming cannabis can be equivalated without an advanced math degree.

The legal limit in Washington and Colorado is 5 nanograms of cannabis in your system. With Colorado trend-setting in so many ways, that has a decent chance of becoming a widely adopted standard. But how much is that in terms of amount smoked? It depends – on how deeply the smoker inhaled, on the THC content of the marijuana being smoked, and apparently on individual metabolisms, which affects cannabis effects far more than they do alcohol absorption. No matter how you look at it though, 5 nanograms is a very small amount. A recent, admittedly not broad enough to be scientifically citable test done by CNN found stoned drivers driving safely and reliably with over 20 nanograms in their systems. http://www.tokeofthetown.com/2013/02/cnn_high_driving_test_shows_five_nanogram_thc_limi.php

According to Paul Armentano, Deputy Director of NORML (National Organization for the Reform of Marijuana Laws), “Breath test technology is simply a detection test, not a per se indicator of whether subjects are ‘under the influence.’ To date, no such data exists correlating THC/breath detection levels with behavioral impairment (as opposed to breathalyzer detection of alcohol at levels above .08 in blood, which have been correlated as valid predictors of alcohol-induced driver impairment). No scientific study that I am aware of has even attempted to correlate the detection of THC in breath with actual behavioral or psychomotor impairment of any kind. (Moreover, studies that have attempted to correlate THC/blood levels with a significantly increased risk of traffic accident have largely failed to do so.)”

That would seem to support relying not on machines or tests, but again on the subjective measures that are currently our only option. Says Armentano, “Ultimately, if law enforcement’s priority is to better identify drivers who may be under the influence of cannabis, then the appropriate response is to identify and incorporate specific performance measures that accurately distinguish those cannabis-influenced drivers from those who are not, such as via the use of modernized SFSTs (standardized field sobriety tests) or even the use of performance technology such as My Canary — a mobile app that tests memory, balance, time perception and reflexes (mycanaryapp.com) rather than relying on the detection of compounds that are not consistently associated with behavioral impairment.”

How is impairment assessed in RI? We asked RI State Police Lieutenant Malloy: “We use probable cause, but we will call a drug specialist on site. Drug specialists are specially trained. They are in finite supply, but they help identify in the field what people are under the influence of. Of course, we need and are hoping for more of them in RI. The Horizontal Gaze Nystagmus Test and well-known walk-a-line test are not always accepted evidence by Rhode Island judges. But a specialist can make a more binding judgment call.”

There are currently a number of saliva-based testing kits, which return results within a few minutes. Five different brands are being road tested right now by Colorado troopers. There are also companies working on actual breathalyzers – although none of them are predicted to be available for testing for a few years. And so far, none of these can detect cannabis from edibles, only inhaled cannabis. Blood tests, on the other hand, don’t have the necessary time-sensitivity – they can tell if cannabis has been in your system, but not when it got there. And the question of whether it’s the amount of THC in the system or actual impairment that we should be trying to measure will be open for some time.

So if you have a medical license or are planning ahead for legalization, what’s the takeaway from all this? “If in doubt, don’t drive. Get an Uber,” says officer Malloy.