Pot has a lot to learn from alcohol. Alcohol is the senior intoxicant, having been legal in the U.S. since the 21st amendment repealed Prohibition in 1933. Still, pot is catching up; nearly one third of all Americans live in a state where marijuana has been legalized to some degree.
Automobile accidents due to DUI spiked dramatically back in 1933, leading to a flurry of research and the setting of a 0.15% blood alcohol level as the acceptable limit. The real breakthrough came 21 years later with the invention of the Breathalyzer. Thanks to MADD, the limit has since been dropped to 0.08% and when you get pulled over, what you blow determines where you go.
Regardless of where you land on the legalized marijuana issue, there is no denying that stoned drivers do not a safe road make. Sluggish reflexes, slowed decision making, reduced awareness, restricted peripheral vision and potential hallucinations are well-documented effects of pot. It is illegal to drive high in every state in the U.S., but what exactly does that mean?
Alcohol is pretty simple. The higher your blood alcohol level goes, the drunker you get.
Minor tweaks for body weight notwithstanding, the whole DUI concept is pretty black and white. Pot, however, is complicated. It’s active ingredient, THC, moves quickly from the bloodstream to the brain. So far, there is neither a good idea of what a safe threshold for THC might be, nor is there a reliable, convenient field test for checking it.
A weed Breathalyzer may be coming soon, and that will surely lead to a practical legal limit. What we do about drivers who are almost over in both alcohol and pot is a question for another day.