So do alcohol and tobacco. Shall we make those illegal, too? In fact, texting while driving is worse than driving drunk; perhaps we should make cellphones illegal too.
We have clear and enforceable rules about the use of alcohol, the effects of which are well understood, and predictable within close enough parameters to regulate that use, and for those who are generally responsible to avoid being impaired to the degree that they are a hazard to others.
As for tobacco, maybe I should name the places you can't smoke a (tobacco) cigarette any more? Nah. I'm saving my carpal tunnels. The nicotine and tar content of tobacco products is no secret, and smokers can choose to regulate their intake and often do by selecting a brand of their liking.
Likely in the west coast states mj use is sanctioned where tobacco can't be smoked.
But we have no means to anticipate the effects of any given toke off a joint on any given individual. Studies from the past I read (High Times, IIRC) indicate that people will take as many hits off the good weed as they will ditchweed, unless they pass out first--they smoke the same amount, regardless of potency. You don't see that with some switching from an ultralight cigarette to one higher in tar and nicotine, nor is the light beer drinker going to start pulling off the whisky bottle and expect the same effect as drinking light beer.
Because the information on dosages and effects remains sketchy, prediction (and avoidance) of dangerous levels of intoxication remains problematical, and less avoidable, making moderate or just responsible consumption questionable.
Without the ability to predict what dosages are past that threshold from mild impairment to hazard to navigation, the latter becomes more likely.
Ask yourself if you want the pilot of your plane, the driver of the semi next to you on the highway, railroad engineers, power plant operators, etc. to have been baked the night before? Unlike alcohol, the only quick tests are a present/absent, and the active ingredients in marijuana have a loiter time in the body far in excess to that of ethanol, rendering testing even harder.
At least the use of alcohol and tobacco can be regulated, with the results of conforming to those regulations resulting in predictable levels of competency, whether or not people will conform to those regulations. At present, the use of marijuana cannot be regulated in the same fashion.
What I must note is the demonization of tobacco (which possibly
might cause any given individual to get cancer with long term use) in the face of cries to legalize pot, with its universal intoxicant effects.
