And so Barack Obama tells high school kids in New Hampshire that he “made some bad decisions” at their age. He “experimented” with pot and cocaine. This is old news — but even if it were new news, it would be ho-hum in today’s politics.

After all, drug use has proven no bar to high office — at least for those who evaded arrest. Vice President Al Gore, ex-House Speaker Newt Gingrich and Supreme Court Justice Clarence Thomas have all admitted to smoking pot. President Bush refuses to deny that he snorted cocaine. And no one believes that Bill Clinton “didn’t inhale” on that joint.

I would second the ho-hum, except for this: More than half a million Americans now rot in jail for nonviolent drug offenses, some not as bad as Obama’s.

Out of humility and humanity, you’d think that the Illinois senator would use this teaching moment to say: “What we politicians call our ‘youthful discretions’ should not become life-destroying crimes for everyone else. Let’s stop arresting drug users.”

I don’t wish to pile onto Obama, because most presidential candidates support this crashing hypocrisy called the “War on Drugs.” The honorable exceptions are two Democrats, Ohio Rep. Dennis Kucinich and former Alaska Sen. Mike Gravel, and Republican Rep. Ron Paul of Texas.

“You can get over an addiction, but you can never get over a conviction,” Jack A. Cole, who spent 14 years as an undercover narcotics officer for the New Jersey State Police, told me. Cole now heads a group called Law Enforcement Against Prohibition (LEAP), ex-cops who oppose current drug policy.

The lunatic War on Drugs has produced some extraordinary statistics. Since it started in 1970, American law enforcement has arrested 38 million people for nonviolent drug offenses, nearly 2 million last year alone. The number of people jailed for violent crimes has risen 300 percent, but the prison population of nonviolent drug offenders has soared 2,558 percent.

The reason is “get-tough” mandatory minimum sentences for drug-related crimes. “We’re putting violent criminals back on the street to make room in our cells for nonviolent drug offenders,” Cole notes.

The insanity continues under Democratic and Republican presidents alike. During the Clinton era, more people were arrested for nonviolent drug offenses than in all the previous years of the war combined.

And despite his past, Bush has shown no mercy, not even for high-school kids caught smoking pot behind the bleachers. One of the silliest spectacles of his administration was federal agents raiding the backyards of cancer patients growing medical marijuana, as permitted by California law.

The recent rise in cocaine prices has prompted Bush’s drug czar, John Walters, to declare a major victory. Oh? The price of cocaine fluctuates. And it was 40 percent cheaper 37 years ago.

Revulsion against the War on Drugs is starting to gain momentum. The National Conference of Mayors recently voted to end the conflict, as has the National Hispanic Caucus of State Legislators. Cole wants to embolden politicians to say what everyone knows — that the war has been a dismal $1 trillion failure. If they do that, he said, “they’re not going to lose one more vote than they gain.”

Here’s a guaranteed way for one of the leading presidential contenders to rise above the pack: Promise a pullback from the War on Drugs.

Because of his own drug use and vow to apply fresh thinking to old problems, Obama would be the perfect candidate for such a move. He could transform his story to a demand for decency: If having tried cocaine doesn’t disqualify him for the presidency, it shouldn’t be allowed to wreck the dreams of other Americans, either.

Froma Harrop is a Providence Journal columnist. Her e-mail address is fharrop@projo.com.