Since legalizing marijuana use in November, the state of Washington has established legal levels for marijuana for drivers. Just as .08 percent is a driver’s limit for blood alcohol content, five nanograms per milliliter of blood is the new limit for active THC (marijuana’s psychoactive component) while driving.
Testing for Marijuana Use
In most recreational users, active THC will drop below the five-nanogram threshold within two to three hours of using marijuana. Among the heaviest users, active THC levels may never drop below five nanograms — even when they’re not impaired.
Who Should Be Worried?
A test for marijuana use is just that — proof that a person has smoked pot… at some time. Studies have been unable to establish a reliable correlation between THC levels and actual impairment, so drivers who feel completely sober could still fail a drug test. Medical marijuana users have the potential for an automatic DUID conviction every time they get behind the wheel, since THC levels remain higher in heavy marijuana users for longer periods of time.
Confusing (and Maybe Illegal) Rules
There is no roadside test for THC levels comparable to those for testing blood alcohol levels. Officers instead use drug recognition training, observation, and sobriety tests. In Washington, if a driver shows signs of impairment and fails a standard field sobriety test, he can be arrested and taken to a hospital or clinic for blood testing. However, arresting for marijuana DUI based solely on field sobriety tests is not without controversy.
Critics of the new THC threshold argue that it may be unconstitutional because the average citizen has no way of knowing when they’re over the five nanogram limit. The fact that there isn’t a practical way to test one’s own THC level makes this a due process problem.
2 comments
DistributedIntelligence
First off, the burden is on the state to demonstrate that cannabis causes "impairment" to operators of motor vehicles. Good luck with that, it's not a nervous system depressant or an opioid. Unless of course they want to offer a memory test as a requirement for driving.
Robert Foster
Not qualified to make a helpful comment, or contribution.