Seattle police officer Mike Lewis hears it all the time when he pulls over stoned drivers crawling along Interstate 5 at half the speed limit. “But it's legal.” They're right — sort of, says the Seattle Times. Washington state legalized recreational marijuana use last year, but if drivers are too high to safely operate a vehicle, they'll still face a DUI charge.
Just as state law limits drivers to a .08 blood alcohol content, it limits them to five nanograms of THC, marijuana's active ingredient, per milliliter of whole blood. A blood test is the quickest way to tell, but getting one became trickier when the U.S. Supreme Court ruled in April that officers must have a warrant to obtain blood samples. Because many stops are made late at night, when judges aren't available, officers must determine on the scene whether the driver is impaired. Lewis and 200 other officers around the state have been trained to make that determination. As drug-recognition experts, or “DREs,” they get two weeks of instruction on picking out impaired drivers and analyzing their behavior for the presence of alcohol or drugs.