Asked at a Washington news conference Wednesday about Drug Enforcement Administration raids in California since Obama took office last month, Holder said the administration has changed its policy.

"What the president said during the campaign, you'll be surprised to know, will be consistent with what we'll be doing here in law enforcement," he said. "What he said during the campaign is now American policy."

Bill Piper, national affairs director of the Drug Policy Alliance, a marijuana advocacy group, said the statement is encouraging.

"I think it definitely signals that Obama is moving in a new direction, that it means what he said on the campaign trail that marijuana should be treated as a health issue rather than a criminal justice issue," he said.

Piper said Obama has also indicated he will drop the federal government's long-standing opposition to health officials' needle-exchange programs for drug users.

During one campaign appearance, Obama recalled that his mother had died of cancer and said he saw no difference between doctor-prescribed morphine and marijuana as pain relievers. He told an interviewer in March that it was "entirely appropriate" for a state to legalize the medical use of marijuana "with the same controls as other drugs prescribed by doctors."

After the federal Drug Enforcement Agency raided a marijuana dispensary at South Lake Tahoe on Jan. 22, two days after Obama's inauguration, and four others in the Los Angeles area on Feb. 2, White House spokesman Nick Schapiro responded to advocacy groups' protests by noting that Obama had not yet appointed his drug policy team.

"The president believes that federal resources should not be used to circumvent state laws" and expects his appointees to follow that policy, Schapiro said.

The federal government has fought state medicinal pot laws since Californians voted in 1996 to repeal criminal penalties for medical use of marijuana.

President Bill Clinton's administration won a Supreme Court case, originating in Oakland, that allowed federal authorities to shut down nonprofit organizations that supplied medical marijuana to their members. Clinton's Justice Department was thwarted by federal courts in an attempt to punish California doctors who recommended marijuana to their patients.

President George W. Bush's administration went further, raiding medical marijuana growers and clinics, prosecuting suppliers under federal drug laws after winning another Supreme Court case and pressuring commercial property owners to evict marijuana dispensaries by threatening legal action.

The Bush administration also blocked a University of Massachusetts researcher's attempt to grow marijuana for studies of its medical properties. Piper, of the Drug Policy Alliance, said he hopes Obama will reverse that position.

"If you removed the obstacles to research," he said, "in 10 to 15 years, marijuana will be available in pharmacies."

E-mail Bob Egelko at begelko@sfchronicle.com.

This article appeared on page A - 1 of the San Francisco Chronicle