By Jonathan Kaminsky
OLYMPIA, Washington (Reuters) - Marijuana activists in Washington state hope voters will be reassured by strict new "stoned driving" standards, despite opposition from medical cannabis users who say the limits would make it hard for them to ever drive legally.
Washington is among three states voting on Tuesday on whether to allow marijuana for recreational use, even though the federal government considers it illegal, harmful and liable to be abused. Legalization measures in two other states, Colorado and Oregon, contain no new restrictions on impaired driving.
The group behind the Washington state measure has set a clear, measurable red line for blood limits on pot's psychoactive element, which is built into the initiative to be decided by voters. In doing so, they have sought to overcome the failings of a 2010 California legalization referendum, which foundered in part over fears of more deadly car crashes.
But they have also ventured into the heavily contested territory of how to scientifically gauge hazardous levels of pot in drivers, and how limits should be enforced.
Critics say the science around pot-impaired driving is not settled and the National Institute on Drug Abuse says more research is needed to understand pot's impact on driving.
Under the Washington proposal, an average pot smoker would cross the limit after two or three hits from a joint, and remain too high to drive for a couple of hours, said Brian Vicente, co-author of the Colorado cannabis legalization initiative.
Regular medical pot users, because they have more of the drug in their system, could be pushed over the limit after inhaling less of the drug, he said.
No state has ever legalized cannabis for recreational use, but polls have consistently shown the Washington measure leading, if by a narrowing margin.
An Elway Poll of 451 likely voters released last week showed 48 percent support the bill versus 44 percent opposed, with a margin of error of 4.5 percent.
New Approach Washington, the group behind the measure, has far out raised backers of the other two state legalization efforts, taking in over $4.5 million since the measure earned a place on the ballot.
The impaired driving limits are meant to make the measure palatable to a broad swath of voters, said Alison Holcomb, an ACLU lawyer who wrote the initiative and directs the campaign.
"Trying to move such an historic measure, you can't take anything for granted," she said. "There was definitely a political consideration involved."
A dozen states have standards for the amount of THC, the ingredient in pot that makes users high, that drivers can have in their blood. Nine of those states have zero tolerance, and the rest have limits on THC in the blood that are more restrictive than the proposal before Washington voters.
Washington prohibits driving while impaired by marijuana, but does not yet have a specific blood level standard.
Holcomb said legalization proponents had commissioned a statewide poll in May in which 62 percent of 602 likely voters said a pot-impaired driving standard would make them more likely to vote for legalization. Washington is one of 17 states that already allow medical marijuana.
She said Californians rejected a pot legalization measure in 2010 that lacked an impaired driving element after Mothers Against Drunk Driving complained the law would lead to more accidents.
But the proposed impaired driving standards have not won many fans among foes of legal pot.
"I don't think it really would be much of a deterrent," said Steve Freng, prevention treatment manager for the Northwest High Intensity Drug Trafficking Area program, which seeks to curb the use of illicit drugs. Freng fears legalization would lead to more teenagers obtaining marijuana.
In a twist, some medical pot backers oppose the initiative. They say regular medical cannabis users could become outlaws under the proposed driving standard of 5 nanograms of active THC per milliliter of blood because THC can linger in the system. Those under 21 would face a zero-tolerance policy.
"You don't criminalize us and call it legalization just to get (the measure) passed," said Steve Sarich, a medical marijuana entrepreneur who leads the anti-initiative campaign.
A 2006 study cited by legalization proponents shows that pot users with between 5 and 10 nanograms of active THC per milliliter of blood were 75 to 90 percent more likely than sober people to show signs of impairment in driving-related tasks.
Research shows a once-a-week pot user's active THC level drops below the state's proposed legal limit within three hours of smoking, said toxicology expert Stefan Toennes of Goethe University in Germany. Heavy users sustain a higher level of THC longer, but only in extreme cases for over eight hours, he said.
The Washington state measure would create a system to license and tax pot growers, processors and stores. Only those 21 and older could legally buy the drug for recreation.
(Editing by Alex Dobuzinskis and Todd Eastham)