Can Smoking Weed a Month Ago Lead to a DUI Conviction?

The problem with weed is that it tends to stay in your system for at least 30 days, because THC is stored in the body’s fat cells. Compare that to cocaine, which is water soluble, flushing out with the user’s urine within 3 days. If you’re a weed smoker that’s never been in trouble with the law, should this physiological “in-your-system-for-30-day” factoid mean anything to you? Yes. Say you end up in a huge car accident with injuries–the police are going to take blood to check for impairment–and that weed you smoked a month ago will be there. Now you’ve got handcuffs. Jail cell. Mugshot all over the internet. High insurance rates for the rest of your life. And so forth and so on.

People primarily think of driving under the influence (DUI) charges as involving alcohol. That’s true most of the time. But technically, it is a crime to operate a motor vehicle with any amount of drug or its metabolite in your body–if the substance is impairing your driving. It can be tough for prosecutors to prove that you were “under the influence” of the drug at the time, but this can be inferred–and that’s the problem with weed. How can a jury determine whether or not a driver is under the influence of marijuana smoked right before the accident, versus smoking two weeks ago during a visit to Jamaica?

Some states have decided to place arbitrary limits on what is considered impairment by marijuana. Colorado, for example, just passed a law this year which “presumes” a driver is impaired if the weed levels are above 5 nanograms per milliliter. Washington State also makes it illegal to drive with a blood level of 5 ng or more of active THC. The Michigan Supreme Court overturned a DUI conviction earlier this year because the conviction was based upon the presence of trace amounts of marijuana. The Michigan court stated that the lower could should have focused upon proof as to whether or not the driver was “impaired” by marijuana while driving. And, shouldn’t that always be the question when it comes to a DUI charge involving drugs? Even prescription drugs can get you a DUI conviction if they impair your ability to drive.

The problem with setting a limit of 5 ng per milliliter is that most experts cannot predict the effects of THC on drivers. The National Highway Traffic Safety Administration (NHTSA) did a study back in 1993, entitled “Marijuana and Actual Driving Performance”. Basically, the study concluded that “THC’s adverse effects on driving performance appear relatively small.” Furthermore, it was found that “THC’s effects differ qualitatively from many other drugs, especially alcohol. Evidence from the present and previous studies strongly suggest that alcohol encourages risky driving whereas THC encourages greater caution”. Robbe HWJ, O’Hanlon JF; Marijuana and Actual Driving Performance Executive Summary, NHTSA, November 1993.

Arizona is in the thick of this debate right now. Medical marijuana is legal in Arizona, yet citizens who smoke via a valid prescription can be convicted of DUI simply because their system shows the presence of marijuana or its metabolites. This issue has made it up to the Arizona’s Supreme Court, as it seems unreasonable to base a DUI conviction upon THC metabolites. Technically, smoking weed leaves a metabolite called “Carboxy-THC” in a person’s system for 30 days, or more. But, this metabolite does not cause a person to get “high”. In other words, this metabolite (technically called an “inactive metabolite”) has no psychoactive effects on the brain, so there cannot be impairment based upon the presence of Carboxy-THC in a person’s system. If, on the other hand, you’ve smoked within the last couple of hours, a blood test may reveal an “active metabolite”, and these can cause impairment. But, how can Arizona prosecutors argue–with a straight face–that a person is guilty of driving under the influence of marijuana when the only thing found is an inactive metabolite which proves there are no psychoactive chemicals in the person’s system that could physically cause impairment? Following me here? Good.

Judges have the awesome responsibility of deciding what is “relevant” evidence. When evidence seems too remote, a judge should exclude that evidence. In Florida, we defense attorneys will file a Motion to Suppress (or Motion in Limine) to keep out any blood results showing the presence of THC metabolites. Even urine results which show 5 ng or more of THC may be suppressed, because such numbers appear to bear no relationship to actual impairment. This conclusion is supported by numerous experts in the field, as well as studies such as the NHTSA study mentioned above. Is evidence that a driver smoked marijuana a month ago relevant to the issue of whether he was impaired? No, and usually judges will agree.

So, where do Orlando DUI marijuana cases come from? If there’s no accident involved, there’s only one reason cops ask for urine on a DUI case–a low blow. That’s right. Blow into the Intoxilizer 8000 and get a result under 0.08, and you’re going to be pissing in a cup soon thereafter. By the way, no privacy here, some government employee will be watching you urinate. Your private parts will be exposed to some random government employee all because a patrol officer didn’t like the low breath results spit out by their rigged Intoxilizer 8000.

There are problems with such urine requests. Namely, if the officer is dumb enough to admit that he requested urine due to a low breath test (yes, some are, I’m just saying, I’ve seen it), that urine test will be suppressed. The reason is simple: an officer may only request urine if he has reasonable cause to believe that the driver is under the influence of substances other than alcohol. To overcome a defense challenge on these grounds, the officer must articulate facts which indicate drug impairment (as opposed to alcohol impairment).