States Attempt to Sort Out Driving While High Laws — But Are Finding Out Marijuana is Not the Same as Booze

Mother Jones takes a hard look at an issue that's coming to light as medical pot use is on the rise and many states consider legalization: driving while high.

Medical marijuana advocates in Washington derided I-502 before it passed because of its low THC threshold for impaired driving (5 nanograms per milliliter of blood) and that research has shown that THC persists in the body up to a month after ingestion in sizable amounts. Nevada and Ohio have taken a harder line at 2 nanograms, and others have enacted zero-tolerance laws.

While these laws are rooted in drunk driving policies, marijuana researchers have discovered driving while high is not the same as driving drunk.

Jan Ramaekers, a marijuana researcher, said, "The reality is that alcohol and cannabis are two very different drugs that affect people in very different ways."

High drivers tend to slow down and leave room around them while driving, which is the opposite of boozed-up drivers who speed and are overly aggressive. This does not mean high drivers are safer drivers — they're still two to six times more likely to be in accidents.