marijuana DUI

Associated Press

New figures from the Washington State Patrol show that more drivers have tested positive for marijuana since the state legalized the drug last year.

In the first six months of 2013, the patrol's crime lab says, 745 people tested positive for marijuana. Typically there are about 1,000 positive pot tests on drivers in a full year.

Associated Press

Before December, 2012: 

It's a crime to drive under the influence of marijuana if the intoxicant impairs your driving "to an appreciable degree." Prosecutors can use blood analysis, along with other evidence, to prove a person is impaired. But even though marijuana itself is illegal, there's no agreement on what level of THC in the blood constitutes a crime. 

As of December, 2012: 

Justin Steyer / KPLU

When is someone too stoned to drive? Washington's new marijuana law includes a new way to answer that question: a blood limit for the drug.

It's supposed to set a standard just as clear as the .08 blood alcohol content police use for drunk drivers. But one year after voters legalized pot, the line is looking almost as blurry as ever.