The court's watershed ruling, expected by June, likely would settle whether patients may get marijuana as a "medical necessity" even though it is an illegal drug under federal law.
A ruling for the Oakland Cannabis Buyers Cooperative would allow special marijuana clubs to resume distributing the drug in California, which passed one of the nation's first medical marijuana laws in 1996.
A ruling for the federal government would not negate the California voter initiative, but would effectively prevent clubs like Oakland's from distributing the drug.
Several justices seemed skeptical of the marijuana-as-medicine argument in general, and of the notion that marijuana distributors have what the club's lawyers call a medical-necessity defense in court.
That defense would essentially have a judge or jury agree that someone's need for the drug overrides the law. If that is so, the someone should be an actual patient, rather than a business organized to dispense or sell drugs, Justice Antonin Scalia suggested.
"That's a vast expansion beyond any necessity defense I've ever heard of," Scalia said.
Justice Anthony M. Kennedy seemed to agree.
"You're asking us to hold that this defense exists ... with no specific plaintiff before us, no specific case," Kennedy told the club's lawyer, Gerald Uelman.
A vocal assortment of interest groups and activists supporting the use of marijuana as medical treatment mounted an energetic public relations campaign ahead of Wednesday's oral arguments, and activists on both sides gathered outside the court.
One woman carried a picket depicting a red stop sign. It read: "Stop arresting patients for medical marijuana."
On the other side, Scott Rich of the conservative Family Research Council said endorsing marijuana as therapy sends the wrong message to young people.
"Marijuana is not good medicine, to put it simply," he said.
A ruling against the club would mean the government could prosecute distributors aggressively in federal court, regardless of whether states have approved medical marijuana use. That would force providers underground or out of business altogether, advocates of medical marijuana say.
California Attorney General Bill Lockyer is backing the Oakland club, arguing that the state has the right to enforce its law allowing seriously ill patients to ue marijuana.
Some patients and doctors say the drug relieves nausea, improves energy levels and helps combat the symptoms of ailments ranging from cancer to AIDS to glaucoma and multiple sclerosis.
One of the most passionate advocates of marijuana for medical use is Michael Alcalay, 59, who was diagnosed with AIDS several years ago and believes he is alive today partly because marijuana helped him keep his medicines down and his appetites up.
Alcalay, a doctor, is the medical director of the Oakland club and says his interest in marijuana is unquestionably medical. "I don't like getting stoned," explains Alcalay. "I like to be in control."
The Clinton administration sued the Oakland group and five other California distribution clubs in 1998, arguing that the clubs broke federal drug law by distributing, and in some cases growing, marijuana for medical use.
U.S. District Judge Charles Breyer, brother of Supreme Court Justice Stephen Breyer, sided with the government. All the clubs except the Oakland group eventually closed down, and the Oakland club turned to registering potential marijuana recipients while it awaited a final ruling.
Last year, an appeals court revived the case by ruling that "medical necessity" is a legal defense, and Judge Breyer followed up by issuing strict guidelines for making that claim.
Before leaving office, the Clinton administration appealed to the Supreme Court.
The government said the Oakland club flouted the law and continued to distribute marijuana after an order to stop. Then-Solicitor General Seth Waxman also rejected the notion that marijuana could be a medical necessity, and said Congress had spoken clearly on the issue in the broad 1970 law that regulated drug distribution.
A lower court "may not override those determinations by reweighing the scientific and medical data and social policies considered by Congress, the attorney general and the secretary of health and human services, and concluding that the public interest supports the illegal distribution of marijuana," Waxman wrote in legal papers.
Justice Breyer will not participate as the other eight justices consider their ruling. Should the court divide 4-4, the appeals court ruling would stand and the marijuana club would be back in business.
Voters in Alaska, Colorado, Maine, Nevada, Oregon and Washington also have approved ballot initiatives allowing the use of medical marijuana. In Hawaii, a similar law was passed by the legislature and signed by the governor in June 2000.
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