Last week, the Los Angeles City Council voted for a measure that asked the federal government to stop harassing medical marijuana users in California. Minutes later, the Drug Enforcement Administration raided 10 medical marijuana dispensaries in Los Angeles County.

The disrespect for local judgments on local matters could not have been starker. Determined to maintain anti-drug orthodoxy, the DEA is running wild in the laboratories of democracy, smashing experiments in reform and injuring innocent bystanders.

The U.S. Supreme Court has allowed this cruel crusade to continue based on the premise that a cancer or AIDS patient who grows a few marijuana plants to relieve his pain or nausea is engaged in interstate commerce and therefore subject to federal regulation. As for Congress, on the day of the L.A. raids, the House once again rejected a measure aimed at restraining the DEA.

Because the two other branches of the federal government have failed to protect medical marijuana patients, their most plausible hope lies in electing a president who is less intent on snatching their medicine. At this point, the Democrats look decidedly more promising than the Republicans in this respect.

According to Granite Staters for Medical Marijuana, seven of the eight declared candidates for the Democratic nomination have promised to call off the DEA's medical marijuana raids if elected. The eighth, Barack Obama, has said such raids "probably shouldn't be a high priority."

Three of the nine remaining Republican candidates -- Ron Paul, Tom Tancredo and Tommy Thompson -- oppose the DEA raids. But the rest of the Republicans, including the leading contenders, either have taken no position (Mitt Romney) or have said they would continue the current policy (which, it's worth remembering, has roots in the Clinton administration).

When he was asked about medical marijuana in April, the straight-talking John McCain said, "I will let states decide the issue." Less than three months later, asked whether he would end the DEA's interference with medical marijuana use in the 12 states where it's legal, he already had changed his mind, saying, "Right now my answer to you is no." And in five minutes?

McCain's initial position on medical marijuana was reminiscent of George W. Bush's during his first presidential campaign, when he said, "I believe each state can choose that decision as they so choose." At least Bush waited until after he was elected to renege on his promise.

The Republicans also look worse than the Democrats in congressional votes on this issue. It's true that a conservative Republican congressman, Dana Rohrabacher of California, repeatedly has joined Rep. Maurice Hinchey, D-N.Y., in cosponsoring an appropriations bill amendment that would prohibit the DEA from spending money on busting medical marijuana patients and their caregivers. But Democrats have been far more likely than Republicans to back the Hinchey-Rohrabacher amendment, which last week was supported by 66 percent of the Democrats who voted but opposed by 92 percent of the Republicans.

These partisan tendencies do not mean Democrats have greater respect for the division of powers between the federal government and the states. When it suits them, they're happy to support federal involvement in policy areas the Constitution leaves to the states. It's just that Democrats are, by and large, more comfortable with the therapeutic use of cannabis than Republicans are.

It's hard to find a logical explanation for this split. Republicans, conservatives especially, are traditionally critical of overly cautious regulators who prevent people from using drugs that could relieve their suffering safely and effectively. They have a record of supporting the freedom to use herbal home remedies without unreasonable bureaucratic interference.

The prevailing Republican stance on medical marijuana, which is at odds with what most Americans tell pollsters they think about the issue, can be understood only in light of the connotation cannabis acquired as a result of its accidental association with the 1960s counterculture. In fighting a symbol of their opponents' principles, conservatives have sacrificed their own.