NEW YORK (CNN/Money) - Pot should be legal. We could use the money. But that's getting ignored in the wake of this week's Supreme Court decision.

That decision, if you missed it, essentially said that federal law trumps state law and since the Feds say no pot, then no pot. It's a frightening decision on a constitutional level. I've never been a fan of the idea that people in places like California and Mississippi should have a say in how I choose to pursue happiness in New Jersey. And if my state says I can smoke a doobie -- okay, smoke one if a doctor says I need to smoke one -- what gives people in an entirely different state, through our federal system, the right to say I can't? Thomas Jefferson would tell me to fire up.

But the Supreme Court said no, based on the interstate commerce clause. You see, the feds can regulate a local activity, like growing pot in your backyard, if it can conceivably affect an interstate market, like the $10.5 billion market for marijuana. Hey, the argument is as honest as the pothead contingent arguing that this case was only about using marijuana to ease the pain and suffering of disease-stricken people. Once doctors can write prescriptions for pot, the market is de facto legalized.

"The medical argument was kind of a Trojan Horse," says Jeffrey Miron, an economics professor at Harvard University. "It would have been nice to keep the argument a straightforward discussion about marijuana use."

And that, conservatively, is about a $14 billion discussion, the professor argues in a study released this month.

According to his calculations, the government would save $7.7 billion a year if it didn't have to spend money policing and prosecuting marijuana activity. Then, if the feds taxed marijuana at a rate comparable to cigarettes and booze, another $6.2 billion would come rolling in.

Lots of that money -- both the cost savings and the tax money -- would go to the states ... states that right now are facing budget crunches because of a slowdown in federal funds. And of course the remainder would go to the federal government, which has deficits of its own. Hence the cutback in state funds.

The professor's analysis is pretty conservative. And Milton Friedman and 499 other economists cited it in an open letter calling for legalization. And the study doesn't even take into account ancillary economic effects, like jobs created or the growth of related industries (you know, bong makers).

"Unfortunately the economic arguments seem to be turning less relevant right now," said Miron. "... There are those who argue that marijuana should be given treatment comparable to tobacco and alcohol. That they should have the same weight. But people generally still see these substances in different camps."

Obviously there are still important arguments beyond money. One is that pot leads to stronger drugs -- a debate that can easily be transferred to liquor sales. The second is health. You can't tell me pot smoke is any better than tobacco smoke ... and I still get irate about some of my hefty health-care premiums going to pay for somebody who couldn't muster the willpower to quit smoking.

Still, money talks. Or tokes.

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Allen Wastler is Managing Editor of CNN/Money and appears on CNN's "In the Money." He can be emailed at wastlerswanderings@cnn.com.