For doctors who want to discuss using medical marijuana with their patients, the line between advice and advocacy remains almost as blurred as it was before a recent court decision guaranteed a physician's right to address the issue openly.

Some doctors are relieved that the United States Supreme Court let stand a lower-court decision two weeks ago that barred the federal government from punishing doctors who advised patients that marijuana might ease some symptoms.

But some doctors are also perplexed, and even inhibited, by part of the underlying court decision at the center of the case. That decision essentially affirms the federal government's right to hold physicians accountable if they actually take steps to help patients obtain marijuana.

"This decision says that it's fine and appropriate to talk with patients about medical marijuana, and I can even say, `I think you can benefit from it,' said Dr. Steve O'Brien, who estimates that a fifth of his H.I.V. patients at the East Bay AIDS Center in Oakland, Calif., use marijuana for medical purposes. "But does that mean I can now sign a form from a medical pot club or write, `I recommend marijuana,' on a prescription pad? I don't know. It's still kind of murky."

The governing language is found in a decision in 2002 by the United States Court of Appeals for the Ninth Circuit. Of the nine states in that circuit, seven have laws on medical marijuana. The court stated unambiguously that doctors had a First Amendment right to discuss with patients the possible benefits of marijuana for relief of pain, nausea and other symptoms suffered by people with ailments like cancer, H.I.V. and glaucoma.

The court also clearly left open the possibility that doctors could be charged under federal drug statutes. "If, in making the recommendation," the court wrote, "the physician intends for the patient to use it as the means for obtaining marijuana, as a prescription is used as a means for a patient to obtain a controlled substance, then a physician would be guilty of aiding and abetting the violation of federal law."

The ruling stemmed from a suit by California physicians and patients after the federal government had threatened legal action against doctors who recommended medical marijuana. The government issued the warnings in 1996, after voters had approved Proposition 215, the initiative that protected the right of patients to use marijuana for medical indications.

Although doctors are regulated by the states, they receive their authority to prescribe controlled substances through the federal Drug Enforcement Administration.

Dr. Jack Lewin, chief executive of the California Medical Association, acknowledged that the Ninth Circuit's decision and the Supreme Court's refusal to review it left some questions unresolved. Dr. Lewin said he hoped that at least some concerns about discussing marijuana with patients would be reduced.

"The verbal position of the Department of Justice," he said, "was very threatening and put an absolute chilling effect on doctors' communications with their patients. And most did not want to talk about marijuana, much less recommend it."

Doctors in states with medical marijuana laws have long tried to balance state and federal laws that conflict. This month, Gov. Gray Davis of California signed a bill that establishes a state-sponsored identification card for users of medical marijuana, to protect them from arrests, even as the federal government insists that doctors cannot help their patients obtain it. Because of the legal uncertainties, doctors, as well as medical organizations, have struggled to devise ways to avoid running afoul of the law.

The Oregon Medical Association has advised doctors to record only on patients' charts any suggestion that marijuana could help with some symptoms If patients photocopy that part of the medical record and use the documents to obtain marijuana, the president of the association, Dr. Colin Cave, said, the doctor cannot be held responsible.

"We have told physicians to avoid at all costs writing it anywhere else," Dr Cave said. "They should not write it on a prescription pad. They should not write it on a separate letter, because that leaves them absolutely vulnerable to prosecution by the Drug Enforcement Administration."

The language in the Ninth Circuit ruling, Dr. Cave said, does nothing to change those recommendations.

"The D.E.A.," he said, "is still out there, and we know the federal government is not going to give up on this."

With some doctors fearful or reluctant to address the issue, 12 or so physicians from California have in the last few years emerged as consultants on medical marijuana. Those doctors routinely issue recommendations to hundreds of patients who see them expressly for that purpose.

Their activities have drawn intense scrutiny from the Medical Board of California, which regulates medical licenses for the state. The board has investigated at least nine physicians, according to Ana Facio, its deputy chief of enforcement.

The Supreme Court action has no direct bearing on these cases, Ms. Facio said, because the board respects California law and is not seeking to prevent doctors from recommending marijuana. But the board's mandate is to ensure that doctors behave ethically and follow correct standards of care, she added.

"I don't know that I would consider it appropriate medicine to simply sit there and issue recommendations for a fee without a medical history and a physical," Ms. Facio said.

Some doctors view the board's inquiries as overzealous. Dr. Tod Mikuriya of Berkeley, who said he had issued about 20 marijuana recommendations a week, called the investigation of his practice a vendetta. Dr. Mikuriya said he had conducted an extensive review of medical history for each patient and had required documentary proof of illness.

"The prosecutorial mind is boundless in its ways of applying different parts of the law," said Dr. Mikuriya, whose case is still pending before an administrative law judge.

In the region covered by the Ninth Circuit, seven states Alaska, Arizona, Hawaii, Nevada, Oregon and Washington, as well as California have medical marijuana laws. Despite the lingering questions, some doctors in the region consider the Supreme Court decision not to review the appellate ruling as an unmitigated victory.

"I'm home free now," said Dr. William Wenner, 77, a retired surgeon who lives on Hawaii's Big Island and estimates that he has issued more than 400 "certifications" to use medical marijuana in the last few years.

"Who's going to come and get me, and for what?" Dr. Wenner asked. "I'm listening to these people and evaluating their complaints, and I've got three file drawers with their charts."

Three states outside the Ninth Circuit ( Colorado, Maine and Maryland ) have some form of medical marijuana law. Although the ruling is not strictly binding outside the Ninth Circuit, advocates for medical marijuana predict that it will strongly influence authorities elsewhere, especially given the Supreme Court decision to let it stand.

"Frankly, lawyers are ready to pounce on the government as soon as they start harassing doctors anywhere outside the Ninth Circuit," said Daniel Abrahamson, a lawyer for the plaintiffs who is legal affairs director of the Drug Policy Alliance.

Federal officials have promised to continue enforcing the drug laws, reiterating their view that Marinol, an oral prescription drug that includes a form of THC, the psychoactive component of marijuana, precludes the need for using marijuana itself as a medication.

Marijuana contains dozens of ingredients besides THC, and doctors say many patients report that smoked marijuana works better and has fewer side effects than the drug.

"Smoking marijuana is shorter acting, and it's easier to control the dose," Dr. Stephen Becker, an H.I.V. physician in San Francisco, said. "But I'm not indiscriminate. I have to be convinced that the patient has failed the conventional pharmacopeia. I think physicians have a responsibility not to abuse this and get themselves and their colleagues and patients in trouble."

Some doctors are pressing forward with research into medical marijuana, hoping to strengthen the scientific basis for proclaiming its medicinal benefits.

Dr. Donald Abrams, a professor of clinical medicine at the University of California at San Francisco, is one of several investigators with the Center for Medicinal Cannabis Research, which is affiliated with the University of California. Dr. Abrams is studying whether marijuana can relieve the sharp pains that some people with H.I.V. experience in the feet and hands. He is also recruiting cancer patients for a clinical trial on whether marijuana can increase the analgesic effects of other painkillers.

Dr. Abrams said he had discussed medical marijuana with patients since beginning his practice more than 20 years ago.

"People have been using marijuana as medicine for thousands of years," he said. "It's only been in the last 60 years that it hasn't been available in the United States."