If you read the proposal Kleiman’s team submitted to Washington State, you may be a little boggled by the complexities of turning an illicit herb into a regulated, safe, consumer-friendly business. Among the things on the to-do list: certifying labs to test for potency and contamination. (Pot can contain, among other nasty things, pesticides, molds and salmonella.) Devising rules on labeling, so users know what they’re getting. Hiring inspectors, to make sure the sellers comply. Establishing limits on advertising, because you don’t want allowing to become promoting. And all these rules must account not just for smoking but for pot pastries, pot candies, pot-infused beverages, pot lozenges, pot ice cream, pot vapor inhalers.

One of the selling points of legalization is that states can take a cut of what will be, according to estimates, a $35 billion to $45 billion industry and earmark some of these new tax revenues for good causes. It’s the same tactic used to win public approval of lotteries — and with the same danger: that some worthy government function comes to depend on creating more addicts. And how do you divvy up the revenues? How much goes to offset health consequences? How much goes to enforcement? How do you calibrate taxes so the price of pot is high enough to discourage excessive use, but not so high that a cheap black market arises? All this regulating is almost enough to take the fun out of drugs.

And then there is the issue of drugged driving. Much about the chemistry of marijuana in human beings remains uncertain, in part because the government has not supported much research. So no one has come up with a pot version of the breathalyzer to determine quickly whether a driver is impaired. In the absence of solid research, some legalization advocates insist stoned drivers are more cautious, and thus safer. (Hands up if you want Harold and Kumar driving your taxi. Or piloting your airplane.) On this and much else, Washington and Colorado will probably be making it up as they go, waiting for science to catch up.