Police Need a Standard, Reliable Test for Marijuana DUI

Police Need a Standard, Reliable Test for Marijuana DUI

As the legalization of marijuana spreads across the country, the dangers of driving under its influence (DUI) have become a very real problem. The situation has courts and traffic cops scratching their heads. Unlike the ubiquitous alcohol breathalyzer, standard equipment in almost every cop car in America, science has yet to come up with a reliable way to test for marijuana impairment. For alcohol, the breathalyzer and blood tests estimate how much alcohol might be affecting a driver's brain. Scientific testing has established standards for impairment that are accepted everywhere in the world. For marijuana, a blood test can detect some of marijuana's components. But how much marijuana is too much to drive? Nobody knows for sure. Not yet, anyway. Says a recent NPR report: "There's no accepted, standard amount in the breath or blood that gives police or courts or anyone else a good sense of who is impaired." For marijuana, it's a whole new scientific ball game.

There's no doubt that marijuana does impair

Marijuana proponents frequently preach that the drug doesn't affect driving the way alcohol does. Marijuana apologists and legalization activists "cherry pick" from scientific tests that make driving while stoned "probably" safe or "safer than alcohol." That message is demonstrably dangerous because too many people believe it - especially younger people. Someone should ask these marijuana-is-safe people if they'd like to get a heart transplant or brain surgery from a surgeon who smoked marijuana right before the operation. The facts are that marijuana does impair judgment, motor coordination, and reaction time, and significantly so. A whole slew of scientific tests clearly demonstrate "a direct relationship between blood THC concentration and impaired driving ability," says the National Institute on Drug Abuse (NIDA). "And marijuana is the illicit drug most frequently found in the blood of drivers who have been involved in vehicle crashes, including fatal ones." Here's some convincing evidence from NIDA, with an explanation why it's causing such headaches for the cops and the courts: "Two large European studies found that drivers with THC in their blood were roughly twice as likely to be culpable for a fatal crash than drivers who had not used drugs or alcohol. But the role played by marijuana in crashes is often unclear because it can be detected in body fluids for days or even weeks after intoxication and because people frequently combine it with alcohol. "Those involved in vehicle crashes with THC in their blood, particularly higher levels, are three to seven times more likely to be responsible for the incident than drivers who had not used drugs or alcohol. The risk associated with marijuana in combination with alcohol appears to be greater than that for either drug by itself."

Is the problem solvable?

So the major problem is twofold: a) marijuana can remain detectable in the blood stream for weeks; and b) what negative effects it may be having is, so far, impossible to gauge. Here's a good example: In one study, researchers had 30 frequent marijuana smokers stay at a research facility for a month with no access to any drugs. Their blood was frequently tested for evidence of cannabis. "And it shocked everyone, including ourselves, that we could measure, in some of these individuals, THC in the blood for 30 days," said a former NIDA scientist who was the study's toxicologist. Even though they had abstained from marijuana for a full month, stores of THC continued to "leech out." In some heavier marijuana smokers, blood THC remained above the 5-nanogram level (a very high level) for several days after they had stopped smoking. To confuse things, another study found that occasional users could smoke a joint and show no evidence of cannabis in their blood at all.

Where will it all lead?

Obviously, current marijuana blood testing technology is less than useful. But a few scientists are working on tests and standards that might eventually help traffic courts, and cops at the roadside, upgrade to something more useful than observing vague behavioral indicators. In an article about marijuana impairment, TIME magazine recently said a national roadside survey of weekend nighttime drivers found 8.3 percent had some alcohol in their system while 12.6 percent tested positive for THC. And the THC levels were up from 8.6 percent in 2007. It's illegal in all states to drive under the influence of anything, TIME points out. But establishing the .08 breath alcohol limit in most states took years of work to come up with. The question is whether we can establish a similar threshold for marijuana in a reasonable time - before more accidents happen. It's a big question, a big problem, and it's only going to get bigger until the scientists sort it out.

Meanwhile, here at Novus, we continue helping those with drug and alcohol problems get their lives back. Our message to everyone is to avoid all psychoactive substances whenever and wherever possible - especially when performing tasks that require good judgment and coordination like driving.

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