June 6 (Bloomberg) -- The U.S. Supreme Court dealt a setback to the medical marijuana movement, ruling that federal narcotics laws ban the drug even when it never crosses state lines and is used only to relieve pain or nausea.

The justices today said Congress's power over interstate commerce is broad enough to let it outlaw locally grown and used medical marijuana. The 6-3 ruling, issued in Washington, overturns a lower court decision that had let two California women use cannabis to treat medical symptoms.

California and nine other states exempt seriously ill people from laws banning cultivation and use of marijuana. Today's ruling means people in those states nonetheless will face the risk of federal prosecution if they use or distribute marijuana.

The decision is a win for the Bush administration, which said the lower court ruling would undermine its efforts to enforce anti-drug laws.

The case brought into tension two themes of the Rehnquist court: the limits it has imposed on the federal government and the latitude it has afforded law enforcement officers. Those issues produced an unusual breakdown among the nine justices.

Joining Justice John Paul Stevens's majority decision were Justices Anthony M. Kennedy, David H. Souter, Ruth Bader Ginsburg and Stephen G. Breyer. Justice Antonin Scalia wrote separately to say he agreed with the result, though not the majority's reasoning.

Congressional Power

Chief Justice William H. Rehnquist and Justices Sandra Day O'Connor and Clarence Thomas dissented. Those three, along with Scalia and Kennedy, formed 5-4 majorities in a series of previous cases that limited the power of Congress.

The court ruled against Angel McClary Raich and Diane Monson, Northern California residents whose doctors say all other medicines failed to treat their symptoms or caused intolerable side effects.

It's the second time in four years that the high court has ruled against medical marijuana advocates in a fight with the federal government. In 2001 the court said the U.S. Controlled Substances Act, which bans marijuana and other drugs except for use in government-approved research projects, doesn't contain a ``medical necessity'' exception.

The case is Gonzales v. Raich, 03-1454.

To contact the reporter on this story: Greg Stohr in Washington at gstohr@bloomberg.net.

Last Updated: June 6, 2005 10:47 EDT