David Frum points out that the shooter is rumored to be a pot smoker. So, hey, maybe it's time to "regulate" marijuana:

After horrific shootings, we hear calls for stricter regulation of guns. The Tucson shooting should remind us why we regulate marijuana. Jared Lee Loughner, the man held as the Tucson shooter, has been described by those who know as a “pot smoking loner.” ...After the Tucson shooting, there may be renewed pressure to control the weapons that committed the crime. But what about the drugs that may have aggravated the killer’s mental disease? The trend these days seems toward a more casual attitude and easier access to those drugs. Among the things we should be discussing in the aftermath of this horror is the accumulating evidence of those drugs’ potential contribution to making some dangerous people even more dangerous than they might otherwise have been.

Marijuana is illegal—illegal to grow, sell, distribute—and federal, state, and local governments spend billions of dollars annually trying to stamp out pot. And yet pot remains cheap and readily available. They can't keep it out of prisons. Yes, some people shouldn't smoke pot, just as some people shouldn't, oh, own guns.

But if we want to more effectively regulate pot—if we want to do a better job of keeping pot out of the hands of those who shouldn't use it (because they're too young or too messed up)—we need a legal and regulated marijuana market, not the illegal and regulated market we have now.

Look, David, pot is as accessible as it is because it's illegal. So long as it's illegal to sell pot to anyone, an unlicensed pot dealer has no incentive to make distinctions between selling to a child or a nut or a responsible adult. Indeed, he has an incentive to sell to anyone, to move his supply. But if pot dealers were licensed to sell their product—if pot dealers had licenses they could lose—they would be very careful not to sell pot to children or nuts, just as bar owners with liquor licenses to lose are careful not to serve minors or over-serve drunks. It's not a perfect system—some minors manage to get their hands on booze—but it would do a better job of keeping pot out of the hands of kids, fuckups, and nuts than the system we've got now.