Medical Marijuana & Driving Safely: Compatible or Paradox?

A recent news article titled; “In the medical marijuana age, how high is too high to drive?” introduced the idea of writing new traffic law to define legal limits for drugged driving. 

This concept was brought to light in Colorado by state Senator Steve King.  Twelve years ago Colorado legalized the use of marijuana for medical purposes and reportedly more than 85,000 people have been certified by the state health department to use it.  Looking at the time period from 2006 to 2010, there were more than 300 fatal accidents involving drivers who tested positive for cannabis.  These sobering facts are the main reason for introducing the concept of a legal limit for marijuana intoxication.

Other state legislators are making the connection between drugged driving and traffic fatalities.  In California, Assemblywoman Norma Torres reportedly wants to set a zero-tolerance ban on driving under the influence of any drug, including marijuana.

Critics of these proposals argue that the ways that cannibis affects the human body are different than alcohol, the practical testing hasn’t been developed, and medical science hasn’t concluded what limit should be set as acceptable versus unacceptable for driving while having previously used medical marijuana (or other drugs for that matter).

How are states handling this now and what do they propose?

“According to the National Conference of State Legislatures, 17 states have what are known as “per se” laws regarding drugs and driving. That means anyone driving with traces of an illegal or impairing drug in his or her system is breaking the law. This is closer to a “zero tolerance” policy than the 0.08 percent blood alcohol content states have for drunk driving.

However, of those states that have per se laws, Arizona, Delaware, Michigan, Nevada and Rhode Island also allow medicinal marijuana, setting up an inherent conflict in their laws.

Marijuana is currently on unsure legal footing: Even as states are beginning to create a legal framework for allowing use of the drug, the federal government still classifies marijuana as a schedule I drug alongside LSD and heroin and has recently begun raiding dispensaries and arresting cultivators. The drug’s tenuous legal hold has created “a mess for enforcement for impaired driving,” says Chris Cochran, deputy director of public information for the California Office of Transportation Safety.

…In an attempt to create something like the clear standard that exists for alcohol intoxication, Nevada set a limit for THC in the blood at 2 nanograms of THC per milliliter of blood. That’s about 2 billionths of a gram of THC – one gram is about the weight of a paperclip – in one drop of blood.

In Colorado, state King’s bill would set a limit of 5 nanograms of THC per milliliter of blood. And in Washington state, the ballot initiative that would legalize recreational use of marijuana would also set a limit of 5 nanograms of THC per milliliter of blood.

Advocates of medical marijuana say the science isn’t supportive of adopting such specific limits. They worry that this approach will cause drivers who aren’t impaired but have lingering traces of THC in their blood to lose their drivers’ licenses. [emphasis added]

Research has not found a consistent intoxication standard similar to a 0.08 percent blood alcohol content.

While most “over the road” truckers have substance abuse screening programs in place (FMCSR Part 382,, many commercial fleet operators are not regulated in this area.  The question remains, will drivers who get approved for medical use of marijuana and report for duty on Monday morning drive safely?  What happens if they are involved in a tragic collision with fatalities and the circumstances lead to extended litigation with discovery of the alleged “impairment” of the driver?

Would these laws (as proposed in Colorado and California) be enforceable and/or helpful in curbing driving “under the influence” of medical marijuana?

Do these proposals go far enough?  Is it equally important to document what concentration of antihistamines, Valium, antipsychotics, barbiturates, and codeine ( is “too much” in a person’s system to drive safely?

Come join our discussion on this and other topics at our networking group on Linked In! (search groups for “SafetyFirst Client Networking”)

4 thoughts on “Medical Marijuana & Driving Safely: Compatible or Paradox?

  1. I believe there should be extensive research into this matter. There has to be limits as to what levels in the blood constitutes intoxication. Research was done to evaluate alcohol levels in the blood, the same should apply to marajuana.

    • Is driving and using cannabis ‘safe”? The real question is, compared to what? Driving and: Eating? Drinking coffee? A beer? distracted by a car full of kids? Loud stereo? Pretty girls? Fatigued? My answer is: It depends. Here’s a study done for the US DOT: . Their conclusion is it’s effect on drivinmg is no worse than a blood alcohol content under 0.08%, which is still legal last I checked. The study notes that cannabis users are not nearly as reckless and agressive as drinkers.

      Compare that to the millions of drivers who are on prescription and OTC drugs. That nice lady with a back problem tooted on Oxycontin, or the guy on the way home from the dentist with a mouth full of Novocain, never mind the enraged boozer. The mind boggles. But for some reason, people focus on a drug who’s worse side effect is the munchies.

      Montana PBS did a pretty good program called “clearing the smoke: the science
      of cannabis.” I recommend it. While it does not address cannabis and driving per se, it does focus on the institutionalized ignorance that pervades federal agencies on the topic, and they make getting permission to do further studies very difficult. So the ignorance persists.

      I’m not championing the stuff, but I hate to see people support laws and penalties based on opinion, not fact.

  2. If you’re going to legalize the stuff, then it falls into the same category as booze. If you’re “impaired” and driving, then you’re busted. Anyone advocating a Zero-Tolerance policy is simply not in touch with reality. There has to be some set limit, otherwise, people who are 99.9% clear-headed who had last smoked 6 or even 12 hours ago, could still test positive, and to me, THAT would be unlawful. You’re busting someone for driving while impaired, when they’re NOT driving while impaired! At the same time, we legally allow alcohol consumption up to a .08% BAC level. If one’s argument is that pot is illegal and therefore should have a Zero Tolerance, they’re missing the point! These are 2 separate issues! Traces of pot would be breaking the law for usage, not for impairment of a motor vehicle. Each is a totally different issue, with overlapping possibilities, hence the threshold. Also, there should be no difference whether you were smoking it for medical reasons or recreational reasons. If you are IMPAIRED, you should not be driving, PERIOD! You don’t get an exemption, or free ticket to hurt or kill someone, just because your doctor wrote you a scrip. The only real, unanswered question here, is at what limit do you consider someone to be “impaired”?

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