Amid weed wars, stoned-driving laws still half-baked

San Francisco Chronicle
By Peter Fimrite

There are certain telltale signs that a person is stoned: bloodshot eyes, forgetfulness, ravenous late-night cravings.

But the November ballot measure that would legalize recreational pot in California says nothing about how police should detect tokers who climb behind the wheel. There’s no marijuana equivalent to the famed blood-alcohol content tests — taken by breath, blood or urine — that have planted .08 into the American consciousness.

It’s not a pressing concern for marijuana advocates, even as entrepreneurs try to develop a better sobriety test for dope smokers. But it’s a big quandary for California law enforcement officers, who are facing a question that has vexed several other states where recreational pot is legal.

California law bars driving under the influence of psychoactive substances, including weed. But with no definitive measurement for intoxication, arrests are often challenged, with officers relying on evidence like indecisiveness behind the wheel or a pungent car interior.

The lack of clear parameters for driving while stoned is one reason many police agencies and political leaders have opposed the Adult Use of Marijuana Act, known as Proposition 64. Voters in four other states also will weigh in on legalization, and they could join Colorado, Washington, Oregon, Alaska and the District of Columbia in sanctioning adult use of the drug.

“It’s very problematic because we would be basing any type of prosecution on field sobriety tests,” said Ken Corney, the president of the California Police Chiefs Association, which is opposing the initiative on the Nov. 8 ballot. “The potential for people driving around under the influence is increased by not having adequate measures to make an arrest or to prove impairment.”

Constant challenges of field sobriety tests, Corney said, “can take time, resources and can further burden the criminal justice system.”

Advocates for marijuana legalization and some experts following the issue, however, see the focus on doped driving as a distraction, questioning whether authorizing pot use would affect the roadways of a state that already has a ripe medical cannabis industry.

Some recent studies have called into question purported connections highlighted by legalization opponents between marijuana use and car accidents. A report last year by the National Highway Traffic Safety Administration stated the agency “did not find an increase in population-based crash risk associated with THC use.”

Andrea Roth, an assistant law professor at UC Berkeley and an expert on pot legalization, called claims by elected officials, law enforcement groups and the National Institute on Drug Abuse that pot has contributed to a rise in accidents “scientifically irresponsible.”

The debate stems from the nature of the drug: The active ingredient in pot, tetrahydrocannabinol or THC, is fat-soluble and binds with different receptors in the body than alcohol, which is water-soluble. As a result, THC levels can be the same in a person who smoked 15 minutes ago or two days ago.

It is therefore extremely difficult to prove that a motorist who appears stoned is actually impaired, experts say.

Things were simpler when marijuana was fully illegal. Any amount in the blood or in the car could have led to charges. But Proposition 215, the 1996 law that approved medical marijuana, made it legal for people with a doctor’s permission to have some THC in their system.

Prop. 64 would legalize the use and possession of up to an ounce of marijuana for anyone 21 or older and allow adults to grow as many as six plants for personal use — though using pot in public would remain illegal. The new rules essentially mean toking and driving is OK as long as the partaker isn’t addled.

Law enforcement officials expect the number of stoned drivers to increase if recreational use is permitted. The question is, how much — a joint, a bong hit, a slice of a brownie — is legally safe?

That’s something Colorado legislators have been grappling with since January 2014, when their state became the first to legalize recreational marijuana. Lawmakers there at first set a limit of 5 nanograms of THC per milliliter of blood for motorists. Five other states have set similar limits.

The problem is that recent studies have shown that blood levels can drop below 5 nanograms even when a person is still high. Meanwhile, regular users could have high THC levels even if they haven’t ingested any pot that day, according to experts.

Colorado dealt with the problem by changing the language in their marijuana bill, stating that 5 nanograms in the blood is a “permissible inference” of impairment combined with other factors, like bloodshot eyes and the presence of pot smoke, bags of weed and paraphernalia in the car.

“The state still has to prove that you were impaired … so an accused person can show a doctor’s recommendation for so much per day and argue that they can function at that level,” said Sam Kamin, a constitutional and criminal law professor at the University of Denver who is on the state’s recreational marijuana implementation task force.

In 2014, Colorado law enforcement officials reported a 12.2 percent increase in driving-under-the-influence citations involving pot. The Rocky Mountain High Intensity Drug Trafficking Area, an organization set up to track the impact of legalization in Colorado, said marijuana-related traffic deaths jumped 32 percent from 2013 to 2014.

Marijuana advocates call these numbers misleading, not least because they relied on blood testing to find THC levels.

The increase in citations, they say, only means more people are using marijuana than in the past and that law enforcement officers are looking more closely for it — not that more people are driving high. Also, they say, most of the fatal accidents in the studies involved other drugs and alcohol in combination with pot.

“The well-acknowledged truth is that there is no known relationship between THC blood levels and increased relative crash risk,” Roth wrote in a California Law Review paper. If anything, she said, the studies suggest “that drivers with only THC in their blood are not causing a disproportionate number of fatal crashes.”

Amid the debate, California officials have been pushing for the development of technology to help catch stoned motorists. A 2015 bill that established a state bureau to license, regulate and tax medical pot also authorized research on marijuana-specific field sobriety tests. Many police departments have also been hiring experts who can identify symptoms of drug intoxication in motorists.

One piece of legislation proposed in April would allow California law enforcement officers to use oral swab tests to strengthen cases involving drivers who failed field sobriety tests. The handheld electronic devices, deployed in pilot programs in Southern California and other areas, test for the presence of marijuana, cocaine, amphetamines and pain medications in saliva.

One driver in Kern County was convicted using the readout from his saliva test as evidence, according to prosecutors, who say those tested are more likely to agree to a plea bargain before trial. At least two companies, one in Colorado and the other in Vancouver, British Columbia, are working on marijuana breathalyzer technology.

To marijuana advocates, the push to treat marijuana like alcohol is folly.

“They are entirely different drugs with disparate behavior,” said Paul Armentano, the deputy director for the National Organization for the Reform of Marijuana Laws, known as NORML.

Drunk and stoned drivers behave differently behind the wheel, he said, with alcohol tending to increase driver confidence, which can lead to recklessness. Marijuana, on the other hand, often inspires self-reflection, which can cause motorists to be more cautious and drive more slowly.

A National Highway Traffic Safety Administration study last year found that motorists with a blood-alcohol level of at least .08 were nearly 400 percent more likely to get in an accident than their sober cohorts. Drivers with THC in their systems were about 25 percent more likely than sober drivers to be in a crash.

Joe Rogoway, a Bay Area cannabis industry lawyer, said Prop. 64 could keep some potheads off the road.

“As use becomes available in social settings,” he said, “it will diminish impaired driving because people will have a place to do it — instead of in their vehicles.”

Peter Fimrite is a San Francisco Chronicle staff writer. Email: pfimrite@sfchronicle.com. Twitter: @pfimrite