David Brooks, Ruth Marcus, and Tina Brown want to keep laws against marijuana. They're aiming at the wrong target. Really, we should legalize marijuana and throw people in jail for being fat.

By Brooks' and Marcus' own admission, marijuana itself doesn't necessarily have such bad effects. They both smoked quite a bit of it back in the day and still managed highly successful careers as national opinion columnists. Really, they are worried about marijuana's negative second-order effects when other people smoke it.

Marcus worries about effects on IQ. Brooks says weed makes people unambitious and distracts them from "the highest pleasures, like enjoying the arts or being in nature." Brown is the most blunt, tweeting that "legal weed contributes to us being a fatter, dumber, sleepier nation even less able to compete with the Chinese."

Brooks, Marcus, and Brown want to address these negative effects through a regime of criminal penalties that imprisons at least some subset of the people involved in cultivating, distributing and consuming the marijuana that Brooks and Marcus enjoyed so much in the 1970s. (Brown didn't answer my Twitter question about whether she's ever smoked marijuana but, well, she works in publishing, so we can all hazard a guess.)

But why go after marijuana for its second-order effects? Why not just ban stupidity, laziness, obesity, unambitious taste, or whatever social ills are of concern to national opinion columnists? As Brooks asks, "Laws profoundly mold culture, so what sort of community do we want our laws to nurture?" If the answer is "one where people are thin," the obvious answer is to ban fatness.

Fat is an ideal menace to be targeted with a criminal law. To some extent, it's a subjective matter who is lazy or stupid, but it's pretty easy to figure out who's guilty of being fat. A law against fat would scare people into losing weight. Even independent of actual legal penalties, it would set a strong norm, showing that society is opposed to fatness and wants people to stay at healthy weights. It would lead to improved cardiovascular health, higher labor productivity (fewer sick days!), and longer life expectancy.

Of course, we'd have to actually jail some people for their fatness. (Otherwise the policy wouldn't work!) Those who are jailed might find, upon release, that their records of criminal fatness make it harder for them to find work in their desired fields, such as national opinion columnist.

But we can mitigate the importance of this impact by mostly using fat jail for racial minorities and people with lower education levels. Wealthy white fat people will apologize profusely for their fatness and then go to "fat rehab," ideally led by Jillian Michaels, multiple times if necessary.

This two-track system will make the costs of punishment so trivial to society that you can go ahead and leave it out of any column discussing the pros and cons of fat legalization. Brooks and Marcus provide a good guide at this — their columns show no concern at all about whether the hardworking drug dealers who sold them so much marijuana back in the 1970s should have been imprisoned, because those people don't count. So, too, with the fat.

The logic is unimpeachable. I look forward to Marcus, Brooks, and Brown joining me in my campaign to jail the fat, so that the rest of us may stay thin, and even smoke weed while we do it.