Patients with the progressive and debilitating nerve disorder multiple sclerosis (MS) are among the most frequently cited users of medical marijuana. Television host Montel Williams has been an outspoken advocate for its use, claiming it helps ease his MS-related pain.

However, in a statement released Monday, the National Multiple Sclerosis Society agreed with the AMA that "we still do not have the necessary scientific information to determine the safety and efficacy of marijuana for medical use in MS."

It points to numerous studies where physicians were unable to find the drug effective in reducing symptoms they could measure, such as spasticity. On the other hand, data on a synthetic THC and an oral derivative of marijuana, cannabis oil, "did confirm that people using marijuana feel better in ways that cannot be measured by their physicians," such as their own perception of pain, according to a society statement.

The bottom line? "More research is needed to determine the potential role of cannabinoids in MS treatment," the society concludes.

Monday's high court decision stems from the 2001 arrest of two California residents -- Angel Raich, who suffers from brain cancer; and Diane Monson, who grew marijuana in her garden to combat chronic back pain. At the time, their use of home-grown marijuana was legal under the state's Compassionate Use Act. Both women were arrested, however, during raids conducted by officers from the U.S. Drug Enforcement Agency, sent to enforce the federal ban.

Lawyers for the two women contended that state law protected them from federal prosecution, but Monday's ruling effectively gives the thumbs-down to that argument. Writing for the majority, Justice John Paul Stevens specified that Congress could change federal law to allow medical marijuana use, should it ever choose to do so. In her dissent, Justice Sandra Day O'Connor wrote that states should be able to set their own rules on this issue.

Next week, the House of Representatives is scheduled to vote on an appropriations bill that would prohibit the Justice Department from spending money to enforce federal drug laws against patients using medical marijuana. While a similar amendment failed last year, 19 Republicans voted for it. The bill was not brought to a vote in the Senate, The New York Times reported Tuesday.

John Radulovic, a spokesman for the National Hospice and Palliative Care Organization, stressed that the vast majority of patients in serious chronic pain do have analgesic alternatives besides marijuana and its derivatives.

"I think most hospice and palliative care physicians are very experienced, so I've heard that in about 95 percent of cases professionals trained in pain management can bring pain under control with legal means," he said. He added that his organization "doesn't support illegal drug use. We do, however, recognize the right a patient has for self-determination. We certainly wouldn't deny care to a patient based on any [treatment] choice they would make."

For Lamers, the Court's decision remains disheartening. "The law must be changed," he said. "I can't support breaking the law and I can't advise others to do it. All I can say is that as a doctor who does an awful lot of work with patients in pain, marijuana is a very effective, safe and relatively inexpensive pain reliever."