Driving After the Influence

Oregon medical marijuana patients might have reason to worry if the state of Washington's dope legalization initiative passes in November—that is, if they ever plan on driving in Washington.

"There's a poison pill in the bill," says No on I-502 campaign spokesman Steve Sarich, a pro-marijuana activist.

At issue is a provision in the Washington measure establishing a maximum amount of THC, the intoxicant in marijuana, allowed in a driver's blood.

If I-502 passes, any amount above 5 nanograms of THC per milliliter of blood could result in a driving under the influence of drugs (DUID) charge.

There's reason for marijuana smokers to worry. More than 275,000 vehicles cross the Columbia River daily, and in them are some of Oregon's 54,280 medical marijuana patients. 

Portlander Anthony Johnson, who heads the National Cannabis Coalition, says Oregonians should beware.

"It definitely affects anyone who uses cannabis heavily," Johnson says.

Activists in Washington argue the cutoff point is arbitrary, noting that THC stays in the blood of heavy cannabis users long after they've stopped smoking. 

A 2011 National Institute on Drug Abuse study found that THC could stay in the blood for up to 33 days at very low levels, and concluded the presence of THC in the blood does not necessarily indicate a state of intoxication or impairment.

"NIDA people are pretty staunch anti-drug advocates," says Philip Dawdy, a Seattle pro-marijuana activist (and former WW reporter) opposed to the measure. "If you have federal researchers saying that, it's explosive."

I-502 campaign manager Alison Holcomb says concerns about unimpaired drivers being arrested are unwarranted.

"Nothing will change in terms of how the DUI laws are enforced," Holcomb says. "The arresting officer still has to have evidence of impaired driving."

Under current Washington State Patrol procedure, officers must bring in a drug recognition expert if they suspect a driver of marijuana impairment. The expert then determines whether there is reasonable cause to have the driver take a blood test.

The only thing that will change if the measure passes is the new THC standard.

Holcomb says backers of Washington's legalization measure added the DUID provision because voters like it.

She notes that other medical-marijuana states, such as Ohio and Nevada, have stricter standards than Washington proposes: 2 nanograms of THC per milliliter of blood. Some states, such as Michigan, have zero THC tolerance.

NIDA investigator Marilyn Huestis says some occasional users of cannabis can be impaired with THC levels as low as 1 nanogram per milliliter, which means Washington's proposed limit is liberal.

"Many people are looking for a per se law for drugs in general that's much lower," Huestis says.

Like Washington, Oregon has no fixed threshold for marijuana impairment.

For minors, the proposed Washington law is much stricter. Drivers under 21 face a DUID for any trace of marijuana.

Sarich, the spokesman for No on I-502, says that's another reason his group opposes the measure.

"We have medical marijuana patients who are under 21," he says. "They have to decide whether to stop their medication or stop going to work.” 

WWeek 2015