Thirty years ago, a college kid in Kentucky was caught growing marijuana plants in his closet. That turned him into a convicted felon, and though he’s been on the right side of the law ever since, he still can’t vote. On any job application, he must check the box next to “Have you ever been convicted of a felony?”

All this misery for growing a plant whose leaves the past three presidents admit having smoked.

We know this story because Sen. Rand Paul of Kentucky keeps telling it. That a Southern Republican probably running for president is condemning such prosecutions as unfair speaks volumes on the collapsing support for the war on marijuana – part of the larger war on drugs.

Two states, Colorado and Washington, already have legalized recreational pot. And the Colorado Supreme Court has been considering a question no one would have dreamed of asking two decades ago: whether an employer may fire a worker for smoking pot.

So what do we do about the rest of the war – the war on heroin, cocaine, methamphetamine and the other nastier stuff? The answer is legalize them, too.

“What is the benefit, what have we derived from this drug war that even begins to offset the horrors we inflict on ourselves via this policy?” asks Dean Becker, a legalization advocate. He is editor of “To End the War on Drugs,” a collection of politically diverse views published by Rice University’s Baker Institute for Public Policy.

Over the past 40 years, the war has put more than 45 million Americans under arrest and cost taxpayers $1 trillion. And what do we have to show for it? Drugs on the street are cheaper, more powerful and more abundant than ever.

The war has fueled gang wars in our cities and enriched the criminal foreign cartels. It has created a vile class system, turning millions of poor and working-class Americans into felons while largely turning a blind eye toward users of the same drugs in suburban cul-de-sacs.

And again, it’s all been for naught. This summer, counties circling Houston, where Becker lives, have seen eight busts of major marijuana growing operations. Law enforcement just stumbled across them.

“There are some indications they were run by Mexicans sent by the cartels,” Becker, formerly a member of the U.S. Air Force security police, told me.

And what does the arrest of a drug trafficker do? It creates more business for the other drug traffickers.

As the conservative economist Milton Friedman once put it, “If you look at the drug war from a purely economic point of view, the role of the government is to protect the drug cartel.”

Wouldn’t legalizing all drugs set off a new explosion of drug use? Good question. Undoubtedly, some would try drugs for the first time. But regulating the sale could limit the problems. Portugal decriminalized drugs in 2000 and saw little rise in use.

Becker is not a big fan of small steps in easing the drug laws, though he thinks that’s better than nothing. He wants full legalization.

Just decriminalizing drugs – that is, not arresting people possessing them but keeping their sale illegal – does not take criminals out of the business. And it stands in the way of regulating the drug-making now done by untrained chemists in primitive labs. Furthermore, illegal businesses don’t get taxed.

Prohibition of the 1920s was “decrim.” Alcoholic beverages couldn’t be sold legally, but one could drink them at home. A lot of good that did.

Make drugs legal; regulate them; and tax them. The final destination for the war on drugs should be oblivion, the sooner the better.