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Development of the Marijuana Breathalyzer: A Speedbump in Legalization

Larry Rankin is a non-user who is fascinated by the ins and outs of the ongoing marijuana legalization process.

It would seem the tide has turned in the marijuana legalization debate. Unlike in years past, pro-legalization seems to have all the momentum, and it should. Everything out there that is credible has shown the effects of marijuana to be less destructive than many legal drugs, such as alcohol, tobacco, antidepressants, etc. From the standpoint of a safer high, there just isn’t any obvious, rational reason why marijuana shouldn’t be legalized.

That is until we get into the practicality of legalizing it. Marijuana is like a round peg in a square world: it just doesn’t want to fit. For example, it can be grown naturally, so anyone can grow it in their backyard, which makes regulation and taxation a bit of a headache, but perhaps the biggest problem with legalizing Marijuana is the fact that it stays in your body so long.

Most drugs leave the body within a day or less after use. Yet it is not unusual for THC to embed itself in the user’s fat cells for over a month. There have even been cases in which heavy users have stopped and THC is still present as much as a year after cessation. (1)

The problem this presents is in monitoring if users are under the influence when they shouldn’t be: behind the wheel, at work, etc.

The Shortcomings of the Blood Test

With alcohol there is the simplicity of the roadside breathalyzer, a tried and true system for measuring one’s sobriety. Though there are currently myriad companies chasing the perfect roadside marijuana tester, with many like Hound Labs in California claiming success, we are still a long way from an established pedigree that will hold up under the scrutiny of law. (2)

We do have the certainty of blood tests to determine if someone has enough THC in their system to be deemed “high,” but a blood test can only effectively be used after the fact, not for the prevention of marijuana related accidents. (1) For example, a roadblock can catch drunk drivers before potential injury and the loss of life because of the breathalyzer. A blood test would likely only be of relevance in casting blame after the incident occurs.

And that is if you believe marijuana significantly hinders one’s ability to drive. And what is “high,” anyway?

How Marijuana Impacts the Senses

The prevailing scientific literature indicates that marijuana doesn’t much hinder the performance of singular tasks, but given multiple tasks, such as is almost always the case in real world scenarios, the marijuana user is prone to distraction. This is all in large part due to the fact that the marijuana user’s brain is more active than a non-user. All this unnecessary activity causes problems with things like peripheral vision, understanding the passage of time, multi-tasking, and even balance. (1)

These are all senses that we use to keep our vehicles on the road. That said, some studies have shown that people under marijuana’s influence are (at least comparatively) safer than drivers under the influence of alcohol. This is because people who are high on marijuana tend to be aware of that fact, while those inebriated by alcohol do not. (1) In essence, the research shows that marijuana users are more careful drivers than those who are drunk.

Due to the effect on the senses, prudence dictates that people should not drive while high, but for argument’s sake, let’s say that marijuana was proven to not be a significant hindrance to everyday driving: what about activities like driving semis or buses or large equipment?

A double-standard regarding acceptable inebriation levels based on the nature of equipment being used is not without precedent. For example, truck drivers with a BAC above trace amounts (say more than what a person may accidently ingest while using mouthwash) will be given a DUI, while a person of average size can operate their personal vehicle after a couple of drinks with no fear of repercussion. This is because a semi requires more concentration to operate safely than a normal sized vehicle.

But whether it is decided we need to detect inebriation levels for drivers of all vehicles or just some, marijuana represents a regulatory problem. THC is still in the body well after use, regardless of whether or not a person is actively stoned. Testing preventively is very difficult. The current answer is to allow employers to determine whether or not any THC is acceptable for employment based on vocation type, but as legalization becomes the rule and not the exception, this becomes an unreasonable restriction.

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How can a business justify telling employees what they can or can’t ingest away from work and off duty if it is a legal substance? For example, a doctor on call is required to stay sober because while on call they could be asked to perform at any moment. The employer is justified in making this requirement for the safety of patients. However, Doctors are not forbidden to ever drink alcohol, because it is a legal activity that can be enjoyed safely by adults.

The same is true of marijuana, and as it becomes entirely legal, the lack of a marijuana breathalyzer and the nature of THC to stay in our body will make determining who is high a real challenge.

How Far Away is a Breathalyzer System?

Most authorities on the matter agree that it is just a matter of time before a reliable roadside marijuana “breathalyzer” is developed, and it is conjectured by many that the winning system won’t even measure breath, but saliva.(1)

Whatever ends up being the prevailing system, the next obstacle will be proving its reliability, which will likely also take years, and then it is a matter of training law enforcement to use it properly, which again adds to the projected release date of an effective system.

Just to add a little perspective, Dr. Marilyn Huestis, a leading researcher on the effects of marijuana, projected regarding a roadside marijuana test that, “we’ll see these kinds of tests used by law enforcement…within 3-5 years.” (1) This projection was made in a Popular Science article written 4 years ago.

It isn’t even so much that the technology to test THC levels on the spot doesn’t currently exist; it’s that such systems don’t lend themselves to accurate use outside a controlled laboratory with uncooperative test subjects. In a knee jerk reaction, Australia even implemented a saliva-based roadside Marijuana Test way back in 2004. Though it was based on a system that worked well in the laboratory, the roadside version proved to be virtually useless. (1)

How High is High?

But when a reliable roadside test is finally developed, we still have the major issue of determining exactly what it is to be under the influence of marijuana. All regular users will have THC in their system at all times, regardless of whether they are high or not. As a result, the threshold can’t be zero.

So how much THC represents being high? Both Colorado and Washington have decided this number is 5 nanograms or more per milliliter of blood. (1) And what hard science is this based on? When you dig into the data, you find out it’s a guesstimate. They’re using quasi-science to make an educated guess at the threshold in which both regular users and occasional users will be significantly impaired.

But though this number is fairly arbitrary, it’s a jumping off point. The same is true with alcohol. We don’t really know what level makes a particular individual drunk. The threshold used to be .1 BAC for a DUI. Now most states have it at .08. This number isn’t based on any hard science. A first-time drinker driving legally at a BAC of .07 might be lit and a hazard to others, while a seasoned drinker driving illegally at .1 BAC may drive safely. (1)

With this sort of thing there has to be a starting point. There has to be a set level that we can agree upon as being “in the ballpark” of correct, even though drugs, whether it be alcohol, tobacco, marijuana, or Tylenol, affect everyone differently. 5 nanograms today may be changed to 3 or 7 with the perspective of time.

Final Thoughts

The lack of a marijuana breathalyzer is a bona fide obstacle to legalization. Unlike all the same old nonsense that anti-marijuana legalization activists continue to repackage and regurgitate, trying to bide time before the inevitable, this is a problem not imagined or exaggerated that will take time and effort to entirely overcome.

That said, the train remains on the rails and continues to chuck along. Breathalyzer systems will continue to develop and refine. Regulatory measurements will continue to be honed and adapted for increased relevance and accuracy. We will make marijuana fit because it is far less costly than its exclusion.



1. “How Will Police Regulate Stoned Driving?” Popular Science [online]

2. “Don’t Hold Your Breath for a Marijuana ‘Breathalyzer’ Test” Scientific America [online]

This content reflects the personal opinions of the author. It is accurate and true to the best of the author’s knowledge and should not be substituted for impartial fact or advice in legal, political, or personal matters.

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