Officials with the Washington state Patrol say about 8 percent of the drivers they pull over turn out to be impaired by drugs. A lab test verifying marijuana in the blood is a factor in showing driver impairment, they say, but there’s never been a legal limit the way there is for alcohol. That changes with the new law allowing marijuana possession, which takes effect Thursday, Dec. 6. It contains a new limit on marijuana components in a driver’s bloodstream.
