By almost every imaginable metric, marijuana legalization appears to have been given the green light in America, from President Obama's refusal to close down the cannabis stores in Colorado and Washington, to The New York Times' recent high-profile editorial series calling for an immediate end to pot prohibition, to the growing recognition by society-at-large that marijuana is indeed far safer than alcohol, and should be treated accordingly.

But there remains a single, divisive sticking point that threatens to bring this whole social experiment to a grinding halt, and that's the issue of stoned driving. Because on the one hand you have a large group of people who perhaps have no problem with us smoking some reefer, but they're scared to death of people who are “potted up on weed” getting behind the wheel, and on the other hand you have a lot of frequent marijuana smokers who fear they'll be unfairly targeted for criminal prosecution based on drug tests that don't accurately measure impairment.

“In this country, there's a huge controversy over whether there should be zero tolerance [for marijuana and driving] or there should be some level that's acceptable. It's a terribly difficult problem," according to Marilyn Huestis, chief of chemistry and drug metabolism at the Intramural Research Program at the National Institute on Drug Abuse. "We will be looking at what are the kinds of functions that are affected, and whether they are significantly different … whether alcohol is on board or not."

Huestis will be analyzing data collected during a research study conducted at the University of Iowa, where for the past year volunteers have gotten drunk, stoned and drunk/stoned, with the full consent of the federal government, and then taken a few laps in one of the world's most advanced driving simulators.

According to USA Today:
Each of the 19 drivers who completed the six combinations of pot and alcohol gave blood and saliva tests during their drives to check intoxication levels, Huestis says. She says the entire experiment took three years to design and administer. The testing finished this spring, and now scientists are studying the 250 variables checked by the tests. They hope to have initial data available by October.

Hopefully, the government will acknowledge the very complex science involved in properly assessing marijuana DUI's. But in the meantime, just keep in mind, driving while impaired -- on any substance -- is not just criminal, it's dangerous.

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