WASHINGTON – The future of the medicinal marijuana movement and the legal doctrine of federalism are at stake in a closely watched case scheduled for oral argument at the Supreme Court on Monday.

The court is being asked to decide whether a federal ban on marijuana trumps a California law that allows the use of the drug for medicinal purposes.

Ten states now allow the use of marijuana by people living with a variety of ailments, ranging from back pain and glaucoma to cancer and AIDS. In this month’s election, voters in Montana passed a ballot initiative allowing the practice, while Oregon rejected a similar measure. Alaska voted against a proposal to fully legalize marijuana.

On Monday, lawyers representing the attorney general, John Ashcroft, plan to ask the top court to reverse a decision from the 9th Circuit that prohibits the federal government from prosecuting two patients who cultivate and use cannabis for medical purposes under California’s Compassionate Use Act.

The case, known as Ashcroft v. Raich, comes before a court whose members imposed strict limits on the ability of the federal government to legislate outside of areas in which the Constitution explicitly grants it jurisdiction.

A coalition of unlikely bedfellows have stepped in to champion the right of an Oakland mother of two, Angel McClary Raich, to consume the drug every two hours to relieve symptoms associated with an inoperable brain tumor.

The attorneys general of states with stricter drug laws, such as Alabama, Mississippi, and Louisiana, are siding with California, the California Medical Association, and pro-marijuana and drug-legalization groups to argue that states should be left to decide how to regulate marijuana that is cultivated and consumed within their borders.

“Whether California and the other compassionate-use States are ‘courageous’ – or instead profoundly misguided – is not the point. The point is that, as a sovereign member of the federal union, California is entitled to make for itself the tough policy choices that affect its citizens,” states their brief to the court.

The Bush administration, as well as a group of federal lawmakers, and anti-drug groups, counter that argument, saying a state-by-state approach would imperil the national war on drugs, because marijuana is fungible and easily transported.

“Stopping the flow would require each state to set up its own customs controls at its border,” argue seven members of Congress who are active in developing drug policy, including Republicans Rep. Mark Souder of Indiana, retiring Rep. Cass Ballenger of North Carolina, and Rep. Katherine Harris of Florida.

While the federal Constitution allows Congress to regulate activities that affect interstate commerce, the Rehnquist court has narrowed the sweep of the Commerce Clause’s power. In two precedents, the court struck down part of the federal Violence Against Women Act and invalidated a federal law banning guns in school zones.

While the government argues that marijuana is clearly a commercial product that affects a $10 billion-plus interstate black market, advocates of states’ rights argue that it does not reach the high standard set out by the Rehnquist court itself for determining when an activity affects interstate commerce.

Calling Monday’s case “critical” to the future of the federalism doctrine, a group of law professors have also filed a friend-of-the-court brief warning against “robbing” the doctrine of “any force” by defining commercial activity too broadly.

“Despite widespread disagreements in the academy about the contours of federalism doctrine, scholars from many perspectives can agree that this case involves an undue extension of federal authority,” wrote a group of professors who specialize in federalism law: Steven Calabresi of Northwestern University School of Law, Charles Fried and David Shapiro of Harvard Law School, Douglas Laycock and Ernest Young of the University of Texas at Austin, and Ilya Somin of George Mason University School of Law.

Ms. Raich, who is in her late 30s, suffers from life-threatening weight loss, a seizure disorder, nausea, and several chronic pain disorders. She has been using marijuana every two hours for more than five years, according to court documents, and her doctor has asserted that she could die without it. She brought the lawsuit in October 2002 with another patient, Diane Monson of Oroville, Calif., who suffers from severe chronic back pain caused by a degenerative disease of the spine.

Ms. Monson, in her late 40s, grows her own marijuana, while Ms. Raich is too ill to do so and is supplied by two caregivers identified only as John Doe One and Two. In August 2002, police officers and agents from the federal Drug Enforcement Agency seized six of Ms. Monson’s cannabis plants.

In October 2002, the two women sought an injunction to prevent the enforcement of the federal drug law against them. A district judge denied the injunction, but that decision was reversed by a split panel of the U.S. Court of Appeals for the 9th Circuit, which found that the federal law was likely unconstitutional.

Last May, they became the first patients to obtain an injunction against the federal government that allows them to possess, use, and cultivate medical cannabis under federal law.

Medicinal marijuana laws across the country “are certainly in peril,” should the federal government prevail in the case, said the lawyer for the National Organization for the Reform of Marijuana Laws, Michael Cutler.

But regardless of the outcome, he predicted that patients would continue to use what he called “an effective and low-cost medication,” gambling that officials in some states will not go out of their way to help federal agents administer the law.

He said it is too late “to un-ring the bell in states where literally tens of thousands of people are part of medical marijuana collectives.”