How Stoned is Too Stoned to Drive? The Feds Want To Know

Aaron Cole
by Aaron Cole

Puff, puff, pass that bill. Federal authorities want to know how stoned is too stoned for drivers, according to a provision in the recently signed Federal Highways Bill.

The new law directs U.S. Department of Transportation Secretary Anthony Foxx to study the effects of marijuana on drivers and present those findings to Congress by the end of 2016.

As more states legalize marijuana — Oregon and Alaska joined Washington and Colorado with legal pot, and 12 states have decriminalized possession — Congress asked the department to determine how to train police to spot stoned drivers and how to test them.

According to a Gallup Poll this year, 47 percent of American surveyed said they thought marijuana would make the roads less safe in states with legalized cannabis.

Authorities in Colorado initially struggled with how to test drivers and measure levels of THC in their systems. Colorado’s threshold of 5 nanograms of THC to qualify as “too stoned to drive” was met with opposition in 2012. Medical marijuana proponents said the per se limit was too low, but the limit was passed into law anyway.

Interestingly, Westword’s pot critic in Denver, William Breathes, had a resting THC level three-times the legal limit the newspaper discovered in 2013.

This year, the University of Iowa discovered that the marijuana equivalent for 0.08 blood-alcohol content (the legal limit for drunk driving in many states) is roughly 13 nanograms of THC. But marijuana and alcohol are very different drugs. Marijuana lasts far longer in users’ blood streams and is difficult to metabolize.

“Everyone wants a Breathalyzer which works for alcohol because alcohol is metabolized in the lungs,” Andrew Spurgin, a postdoctoral research fellow with the UI College of Pharmacy said in a statement announcing the results. “But for cannabis this isn’t as simple due to THC’s metabolic and chemical properties.”

Nonetheless, the feds want to know how stoned is too stoned, and how many stoned drivers are drunk too. (Anecdotally: Many Denver police officers say that they issue more DUI and driving while stoned tickets at the same time than they issue drugged driving tickets alone.)

It looks like the feds just got a lot of money to find out.


Aaron Cole
Aaron Cole

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  • Corey Lewis Corey Lewis on Dec 15, 2015

    "12 states have decriminalized possession" What does this mean, you just get a fine but not a ride in a police car?

  • Lou_BC Lou_BC on Dec 15, 2015

    Decriminalization just means it is not a criminal code violation. One way to look at is a speeding ticket versus speeding causing death. There will be infractions but they won't mean criminal court or a criminal record. Too many violations would mean a bump up to criminal court. Canada looked at decriminalization a long time ago but once Conservatives got elected the whole idea went up in smoke ;) With that being said, what constitutes an impairment threshold will also depend on which side of the political Isle (chasm) that you sit. The problem with testing for blood levels of marijuana is getting a person to a qualified lab and getting the blood work drawn and run. IIRC Marijuana has a fairly long serum 1/2 life so testing expediency might not be an issue but are you going to detain every suspect during the time it takes to confirm blood levels? Urine tests are cheap, quick and easy to administer but all they provide is a yes/no answer. THC tends to accumulate in adipose so i can see the court defense now..... my client is a former marijuana smoker who just went on a crash diet or the famous Canadian snowboarder who kept his Olympic Gold medal by claiming a failed test was due to "passive" 2nd hand smoke. (Aren't all marijuana smokers passive? LOL) This will be an interesting legal maze to navigate."

  • ToolGuy North America is already the greatest country on the planet, and I have learned to be careful about what I wish for in terms of making changes. I mean, if Greenland wants to buy JDM vehicles, isn't that for the Danes to decide?
  • ToolGuy Once again my home did not catch on fire and my fire extinguisher(s) stayed in the closet, unused. I guess I threw my money away on fire extinguishers.(And by fire extinguishers I mean nuclear missiles.)
  • Carson D The UAW has succeeded in organizing a US VW plant before. There's a reason they don't teach history in the schools any longer. People wouldn't make the same mistakes.
  • B-BodyBuick84 Mitsubishi Pajero Sport of course, a 7 seater, 2.4 turbo-diesel I4 BOF SUV with Super-Select 4WD, centre and rear locking diffs standard of course.
  • Corey Lewis Think how dated this 80s design was by 1995!
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