Medical users of marijuana were dealt a severe blow Monday when the Supreme Court ruled that the federal law classifying the drug as illegal contained no exceptions for sick people who use marijuana for medicinal purposes. 

For the many sufferers of such debilitating diseases as AIDS, cancer and multiple sclerosis who claim marijuana provides enormous relief for the devastating symptoms of their ailments, the high court's 8-0 decision was a major disappointment. 

"In the case of the Controlled Substances Act, the statute reflects a determination that marijuana has no medical benefits worthy of an exception (outside the confines of a government-approved research project)," Justice Clarence Thomas wrote for the unanimous court. 

Thomas noted the act states marijuana has "no currently accepted medical use." 

Justice Stephen Breyer did not participate in the case because his brother, a federal judge, initially presided over the case. 

The case was sparked by the federal government in 1998, when the government sought an injunction against the Oakland Cannabis Buyers Cooperative and five other marijuana distributors. 

U.S. District Judge Charles Breyer, brother of Justice Breyer, ruled for 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. 

The 9th U.S. Circuit Court of Appeals reversed the lower court, ruling that medical necessity is a legal defense. Charles Breyer followed up by issuing strict guidelines for making that claim. 

Voters in Arizona, Alaska, California, 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. 

The cooperative argued that a drug may not yet have achieved general acceptance as a medical treatment, but may still have medical benefits to a particular patient or class of patients. 

Thomas said the argument cannot overcome the intent of Congress in approving the statute. 

"It is clear from the text of the act that Congress has made a determination that marijuana has no medical benefits worthy of an exception," Thomas wrote. 

"Unwilling to view this omission as an accident, and unable in any event to override a legislative determination manifest in a statute, we reject the cooperative's argument." 

Advocates of medical marijuana say the drug can ease side effects from chemotherapy, save nauseated AIDS patients from wasting away or even allow multiple sclerosis sufferers to rise from a wheelchair and walk. 

There is no definitive science that the drug works, or works better than conventional, legal alternatives. 

Several states are considering medical marijuana laws, and Congress may revisit the issue this year. A measure to counteract laws like California's died in the House last year. 

Thomas was joined by Chief Justice William Rehnquist, Sandra Day O'Connor, Antonin Scalia and Anthony M. Kennedy. Justice John Paul Stevens wrote a concurring opinion, joined by Justices David Souter and Ruth Bader Ginsburg. 

The case is United States v. Oakland Cannabis Buyers Cooperative, 00-151. 

The Associated Press contributed to this report