Washington State Patrol says it does not tolerate impaired drivers

Responding to questions about the new marijuana law, the Washington State Patrol said,

With respect to impaired driving, we hope you’ve all heard our mantra by now: We’ve always arrested impaired drivers regardless of the drug involved. It has always been a crime to drive while impaired by drugs whether they be illegal, legal or even medically prescribed. This new law does not change how troopers will determine impairment at the side of the road.  

They do not expect to have the kind of data which would indicate any change in arrests right away, pointing out that there would be no data on arrests not made (assuming a traffic stop disclosed a small amount of marijuana). Their current records simply state "drug" arrest and do not include the (suspected) type of drug.

Their job, they say, is to keep impaired drivers off the road. Reasons for impairment would be up to the courts.

The THC level in a suspect’s blood will not be known for days or weeks after the roadside contact. That will be an issue for prosecutors and defense attorneys not troopers.