Yvonne Westbrook recalls when getting relief from the symptoms of multiple sclerosis meant venturing into seedy parks to buy bags of marijuana from drug dealers.

So she worries that the U.S. Supreme Court's unanimous ruling Monday could mean a return of those days. "Now they've opened us up to the street and all the perils involved," she said.

The high court said there is no exception in federal anti-drug laws for patients to use marijuana to ease their pain from cancer, AIDS or other illnesses.

Westbrook is fearful the ruling could mean the end for the dozens of distribution clubs that sprang up after California passed Proposition 215, the state law allowing people to grow and possess medical marijuana.

"With the clubs you're able to go to a clean, safe, secure environment," she said. On the street, "you never know what you're going to get. You never know who's lurking behind the bush to jump you."

Voters in Arizona, Alaska, Colorado, Maine, Nevada, Oregon and Washington also have approved ballot initiatives allowing the use of medical marijuana. In Hawaii, the Legislature passed a similar law and the governor signed it last year.

Patients like Westbrook could still use marijuana for medical reasons in states that allow it, legal experts said. But it would be more difficult to obtain because distribution violates federal law.

Writing for the court, Justice Clarence Thomas said the Controlled Substances Act of 1970 "reflects a determination that marijuana has no medical benefits worthy of an exception." The only exemption is for government-funded research projects that involve some 200 people.

In Washington, Attorney General John Ashcroft called the ruling a "victory for enforcement of our nation's drug laws."

California Attorney General Bill Lockyer said it would be reviewed for its effect on California law.

"This decision is not the end of the line by any means," said Robert Raich, an attorney who represented the Oakland Cannabis Buyers' Cooperative, one of six marijuana distributors challenged by the federal government.

Raich said the issue of medical necessity was just one of several legal arguments they are ready to make in the future in favor of cannabis distribution clubs.

"We feel we have many other defenses left," said Jeff Jones, executive director of the club. The club was prohibited from distributing pot but has remained open to issue identification cards to verified medical marijuana patients.

Mendocino County District Attorney Norm Vroman said the ruling would not change the way his office prosecutes drug crimes. In Mendocino, people are permitted up to six mature plants and 2 pounds of dry marijuana.

"If the feds want to prosecute these people they can," he said. "In California, the law has not changed one iota."

Joel Karlin, a spokesman for Coloradans Against Legalizing Marijuana, cheered the court decision, saying the narcotic in marijuana is already available in a tablet and will soon be available in a patch.

Karlin added that people who obtain marijuana illegally run the risk of impurities, dosage regulation and adverse effects from smoking it. "It's right that the Supreme Court ruled the way it did. I don't think there is any good need for it."

But Westbrook, 48, who lives in an east San Francisco Bay suburb, says she uses marijuana for pain relief and to control the spasticity that is part of her disease.

"It's not about getting high. I'm too old for that. What it does is provide me with the necessary relief I need in order to live a functional life," she said.

The Supreme Court's decision, which reversed a 9th U.S. Circuit Court of Appeals ruling, was reached by a vote of 8-0. Justice Stephen G. Breyer did not participate because his brother, a federal district judge, presided over the case.

Justice John Paul Stevens, though joining in the overall ruling, said the court should have left open the possibility that an individual could raise a medical necessity defense, especially a patient "for whom there is no alternative means of avoiding starvation or extraordinary suffering."