Should it matter how much marijuana is in your blood?

Feb 6, 2013

It’s always been illegal to drive stoned. But, what that means has changed under Washington’s new marijuana law.

Initiative-502 includes a strict definition of "under the influence" – which some people say is misguided.

The state legislature is considering the issue. Some lawmakers want to amend the initiative, but they aren’t sure how to improve it.

The new DUI standard says, if you have a certain blood-level of the active drug in marijuana, called THC, you are automatically considered guilty of driving under the influence. That level is measures as 5 nanograms per milliliter of blood. 

This took effect on December 6th, and so far, arrests have stayed about the same, according to police, prosecutors and a defense attorney who testified to the House Public Safety Committee.

What's changed for law enforcement is you are no longer an automatic suspect just because your car reaks of marijuana, or there's a baggie of it on the seat next to the driver.

"So, I have to observe other things, the psycho-physical things. Like, if you are very slow to find your driver's license, or if I ask you to find your driver's license and you produce your Visa card, stuff like that," said Olympia police Officer Brian Wylie.

Police say they are looking for impaired driving. If someone smells like pot and drives erratically, then they can bring the driver to a hospital to get a blood sample.

The controversy is around that blood test. Marijuana dissolves in the body differently from alcohol – it fades quickly, but then lingers at low levels, no matter how stoned or sober you are, several witnesses told the committee.

So, marijuana advocates worry someone who is a legal daily user, and happens to run a red light, could get a DUI just for residual chemical in his blood.

Scientists gave the committee conflicting testimony about whether any test for marijuana can predict impaired driving.