Washington and other states are looking into adopting a simple roadside saliva test for marijuana impairment.

This saliva testing would attempt to determine a subject’s level of THC, the psychoactive component of marijuana that actually affects driving. The saliva test would be used to determine if the driver’s THC blood concentration was over the legal limit.

The saliva test would only add confirming evidence to justify a DUI marijuana arrest just as a portable breath alcohol test currently does in cases of alcohol impaired drivers.