Two weeks ago, U.S. drug agents launched raids on 11 medical-marijuana centers in Los Angeles County. The U.S. attorney's office says they violated the laws against cultivation and distribution of marijuana.

Whatever happened to America's federal system, which recognized the states as "laboratories of democracy"?

According to the National Organization for the Reform of Marijuana Laws, 11 states (Alaska, California, Colorado, Hawaii, Maine, Montana, Nevada, Oregon, Rhode Island, Vermont, and Washington) have eliminated the penalties for physician-approved possession of marijuana by seriously ill patients. In those states people with AIDS and other catastrophic diseases may either grow their own marijuana or get it from registered dispensaries.

But the U.S. government says its drug laws trump the states' laws, and in 2005, the Supreme Court agreed.

This is not the way it was supposed to work. The constitutional plan presented in the Federalist Papers delegated only a few powers to the federal government, with the rest reserved to the states. The system was hailed for its genius. Instead of having decisions made in the center -- where errors would harm the entire country -- most policies would be determined in a decentralized environment. A mistake in California would affect only Californians. New Yorkers, Ohioans, and others could try something else. Everyone would learn and benefit from the various experiments.

It made a lot of sense. It still does. Too bad the idea is being tossed on the trash heap by big-government Republicans and their DEA goons.

Drug prohibition -- like alcohol prohibition -- is a silly idea, as the late free-market economist Milton Friedman often pointed out. Something doesn't go away just because the government decrees it illegal. It simply goes underground. Then a black market creates worse problems. Since sellers cannot rely on police to protect their property, they arm themselves, form gangs, charge monopoly prices, and kill their competitors. Buyers steal to pay the high prices.

Alcohol prohibition in the 1920s gave America Al Capone and organized crime. Drug prohibition has given us South American and Asian cartels that finance terrorism. Even the government admits that the heroin trade bankrolls terrorists. Prohibition's exorbitant black-market prices make that possible. In the United States, drug prohibition spawns gangs that are sometimes better armed than the police. Drug prohibition does more harm than drugs.

The war on drugs hasn't even accomplished what it promised to do. Drugs are abundant and cheaper than ever. "ABC News" reported last month, "marijuana is the U.S.'s most valuable crop. The report, 'Marijuana Production in the United States,' by marijuana policy researcher Jon Gettman, concludes that despite massive eradication efforts at the hands of the federal government, 'marijuana has become a pervasive and ineradicable part of the national economy.'"

The destructive failure of the drug war is why it makes so much sense to let states experiment, which 11 of them have done with medical marijuana.

Legalizing only medical marijuana brings its own problems. For one thing, it invites state authorities to monitor the practice of medicine to make sure doctors don't prescribe pot promiscuously.

But government officials shouldn't be the judges of what is and isn't medicine. That should be left to medical researchers, doctors, and patients. The effectiveness of medicine is too dependent on individual circumstances and biochemistry. One size does not fit all, so politicians and bureaucrats should butt out.

More fundamentally, why should only people whom the state defines as sick be able to use marijuana? This is supposed to be a free country, and in a free country adults should have the right to ingest whatever they want. A drug user who harms someone else should be punished, but a peaceful user should be left alone.

Despite my reservations about medical marijuana, the states' experimentation is still better than a brutal federal one-size-fits-all crackdown. There is no role here for the federal government. If the people of a state want to experiment by loosening drug prohibition, that should be their right. Washington should mind its own business. The feds and rest of us should watch. We might learn something.