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Cannabis DUIDs: How Much Is Too Much?

March 25, 2014

Saturday night is coming to a close, and after a relaxing evening full of Trainwreck and camaraderie with your friends, it’s time to go home. As a veteran cannabis consumer, you know the short drive home will be a simple task. Besides, it’d been at least an hour since you inhaled anything other than oxygen and a sleeve of Oreos.

It would be easy to shorthand this article by saying, “Don’t smoke and drive,” but there will always be people who won’t accept that their confidence is not the only thing separating them from a DUID (Driving Under the Influence of Drugs).


Should Alcohol and Cannabis Have Separate DUI Laws?

As technological as we humans claim to be, roadside impairment devices have not kept up with the sprinting pace of cannabis policy reform. Lawmakers in Washington and Colorado established per se limits on THC blood levels with the passage of recreational laws, but some scientists and critics believe these limits to be unscientific and arbitrarily derived.

If you are a regular cannabis consumer, it would behoove you to familiarize yourself with the current state of cannabis DUID measurement and understand that there are more factors at play than you might realize.

How Long Is THC in My System?

Two hours have now gone by since your last breath of cannabis and you feel completely sober, being the seasoned, high-tolerance consumer you are. You may feel unimpaired, but the blood running through you is still riddled with THC. This is because your body stores the chemical for long periods of time — especially if you’re a daily consumer.

One 2009 study published in the journal Addiction examined THC blood concentrations in frequent cannabis consumers, both before and after a one-week abstinence period. The results demonstrated perplexing variability among the subjects, some of which had no detectable THC in their system while others had high concentrations even after seven days of no cannabis. Other studies have also noted significant differences in long-term THC retention between occasional partakers and heavy consumers.


How long does THC stay in your system?

Franjo Grotenhermen, a researcher of cannabinoids and toxicology in Germany, explains why these results are problematic for zero-tolerance laws and per se limits.

“This approach effectively sets the legal limit at the technically achievable limit of detection (LOD), making the legal limit a function of the detectability of a drug, rather than the impairment caused by it,” Grotenherman writes. “Zero-tolerance laws will classify many cannabis users as impaired drivers even if they separate drug use and driving by many hours. The same applies to the increasing number of individuals who legally use cannabis for medicinal purposes and, while not acutely impaired, may present with measurable THC concentrations at all times.”

Science exploring the impact of cannabis on motor skills comes in at a slow trickle, so it could be a while before we have enough research to inspire a change in policy. Until then, frequent cannabis consumers should be aware that everything from body weight to metabolism affect the body’s storage of THC.

Measuring Intoxication

The difficulty of establishing THC blood concentrations that accurately reflect impairment is just one facet of the problem. Another is the technology police use to measure that content, adding another murky layer to the issue.

With one blow of a breathalyzer, a police officer will get a pretty good idea of whether or not a driver has had too much to drink. Because of its complex storage and circulation, no comparable test exists for cannabis intoxication. Nevertheless, police continue to rely on underdeveloped testing to determine a DUID case.


How Does Alcohol Affect THC Blood Concentration?

A study published earlier this year assessed the accuracy of roadside testing methods, including oral swabs and observational sobriety evaluations also known as the Drug Evaluation Classification (DEC) Program. Accuracy was measured by comparing the results with off-site blood tests.

The researchers first evaluate Drug Recognition Experts (DREs) who perform DEC evaluations in Canada, Australia, Europe, and the United States. Data was collected across studies beginning in 1985, both from on-site police fieldwork and controlled lab tests. Field evaluation accuracy ranged from about 74% to 90%. Not bad, until you consider that those accuracy rates cannot possibly include any cases of impairment that went undetected. Controlled lab environments reflect much lower success rates: DREs identified only 30% to 53% of subjects who had consumed cannabis.


California Company to Begin Testing Cannabis Breathalyzer

Oral swabs performed considerably better, with accuracy rates falling between 52% and 100%, depending on the brand. “If on-site oral fluid tests had higher levels of device reliability,” researchers noted, “they could be seen as the best technique, given that they have the ability to detect the psychoactive cannabis compounds indicating recent use or impairment and are less subjective than the DEC as performed by police officers. Unfortunately, these devices have not yet achieved an acceptable level of reliability.”

Urine tests are a whole different beast as they measure for both active THC and its inactive metabolites, which are detectable for days (or weeks for regulars) after use. These tests are becoming less popular for DUID evaluations because, a) they can’t pinpoint recent use, b) the test can be adulterated, and c) most police don’t like touching urine.


The THC detox: Myths, facts, and tips

Researchers believe blood tests are better indicators of intoxication, but given their invasive nature and complexity, they are impractical for on-site use. The authors conclude that current testing methods are not up to snuff, and that more research is necessary to improve measurement, per se limits, and our understandings of cannabis motor impairment.

Know the Law and Your Limits

Shoddy testing and unreasonable THC limits might be a frustrating reality, but it’s our reality nonetheless. For now, they are the cost of forward movement toward legalization, and eyes are turned toward us to act them out responsibly. Knowing the law and, more importantly, your cannabis limits will go a long way while research plays catch-up.

Laws and procedures can vary widely across state and country borders. Some areas like California have vague “effect-based” DUID laws, where a person is only tested if detectably impaired. Other states like Washington and Colorado have an objective cut-off THC blood concentration of 5 ng/mL. And then there are states like Arizona and Georgia who have even less tolerance for drugged drivers, giving DUIDs for any trace of cannabis or its metabolites in the body.


Cannabis Detox Symptoms and Withdrawal Remedies

This puts many of us, patients and adult consumers alike, in an unsettling position where the extent of our personal control goes no further than our actions and decisions behind the wheel. We have just one job: to recognize our impairment honestly and resist driving after recent use. After all, you would hope that an unimpaired driver would never make it as far as that off-site blood test.

Image Sources: Nicholas A. Tonelli, MorganFranjo Groterherman, Jeffrey Smith, Adrianna Broussard

  • Ima Straight

    Make no mistake, there is no way to drive legally in WA if you have used MMJ at any time for weeks! I used it once (for a completely medical reason: horrible muscle spasms preventing me staying asleep so I could get to work). Two weeks later I was given a UA test that showed 4 Ng. I was immediately thrown in jail for “impairment”. Total BS. Cost me $600 to bail and get to work.

    It’s ALL about the money, folks. Not traffic safety. Not whatsoever.

    The legal system is extremely dependent on fines and fees. In places like Seattle, it is the #1 line item in the budget for income! There is huge infrastructure built up around it: very costly attorneys, bail bondsmen, parole officers, police officers, judges, testing labs, ‘treatment’ programs, driving schools, special licenses, 12 step ‘donations’; on and on and on. Since legalization, I’d be very interested to learn the spike in the incomes for these mostly parasitic industries.

    These metabolite tests (urinalysis) are also bigoted: females process fat-based chemistry a little differently. People who are overweight do as well. And people who are older process everything more slowly too. So random, non-evidence-based, MMJ legal threshold levels favor the slim young male. They’re the best drivers already, right?

    I hope to someday see a class-action suit against these random laws made by uneducated,vindictive minions to the ‘crime’ industry. Legalization, whether medical or recreational, is really ENTRAPMENT when it comes to rubber meets the roadside. It’s called “legal”, but they will crucify you for actually believing that and going about your life.

    The only way you are actually 100% safe is not to drive or not to use.

    • Stimpy

      Same issue in AZ. One legal judgement seemed to defeat the very odious ‘metabolite’ thresholds. Then another judgement seemed to reverse that back to where it started. Don’t know where this issue is now.

    • Zachfim

      I don’t know if you realize this but you’re a genius. If we could get social media on a tangent about how police tend to discriminate against fat people, old people, and females in legal states, then it would put a lot of pressure for the states to fix this.

  • Stimpy

    I love it that ‘Drug Recognition Expert’ shares the same acronym (DRE) as ‘digital rectal exam’. And I thought that only men older than 45 or so
    dreaded the DRE. Seems like we should all dread that.

  • Craig Abbott

    1 thc is found in most of our foods. 2. weed is the ONLY i cant say drug more like a vitamin that you smoke, you can become sober really fast being pulled over. that being said if i can sober up instantly when i get upset how is that a drug i mean a drug fucks you up. if im taking the medicine for medical purposes it’s probably not going to fuck you up like that but again you can become sober, you cant do that with alcohol , you cant sober up after drinking. so if i can sober up on weed and not on alcohol i dont see how you can test anyone ever given the simple fact that some people can have the shit in their system for weeks after and some have none, so its fair to arrest the people who do not detox weed like others. i mean that makes sense if you could kick yourself in the arss and fly i mean in that specific world where you could kick yourself in the arss and fly does that make any sense at all