Several U.S. Supreme Court justices expressed reservations on Monday about allowing medical marijuana for sick patients whose doctors have recommended they smoke it for pain.

The justices appeared sympathetic to the federal government’s argument that it has the power to prosecute or take other action against patients who use home-grown marijuana in states with laws allowing medical use.

The justices are deciding whether a federal law outlawing marijuana applies to two seriously ill California women whose doctors recommended cannabis for their pain.

California is one of 10 states allowing medical use of marijuana, experts said.

At issue is whether the federal law, the Controlled Substances Act of 1970, amounts to an unconstitutional use of the U.S. Congress’ power to regulate commerce among the states and does not apply to medical marijuana.

The case is seen as critical to the medical marijuana movement. The Supreme Court last ruled on the issue in 2001 when it said California cannabis clubs may not distribute marijuana as a “medical necessity” for seriously ill patients.

The Bush administration appealed to the Supreme Court after a federal appeals court in California ruled that marijuana used for medical purposes was different from drug trafficking.

The appeals court said states could adopt medical marijuana laws as long as the marijuana was not sold, transported across state lines or used for nonmedicinal purposes.

The lawsuit was brought in 2002 by Angel Raich, who has an inoperable brain tumor and other medical problems, and Diane Monson, who suffers from severe back pain. Their doctors recommended marijuana for their pain.

Monson cultivates her own marijuana while two of Raich’s caregivers grow the marijuana and provide it to her free of charge. In 2002, Drug Enforcement Administration agents destroyed six cannabis plants seized from Monson’s home.

Randy Barnett, a law professor at Boston University who argued on behalf of the two women, said medical use of marijuana was a noneconomic activity that falls outside the power of Congress to regulate trade among the states.

SCALIA ASKS ABOUT OTHER LAWS

Justice Antonin Scalia said Congress also has adopted endangered species laws making it unlawful to possess items such as eagle feathers or ivory. “Are those laws likewise unconstitutional?” he asked.

Justice David Souter asked Barnett about the government’s estimate that as many as 100,000 people could use marijuana for medical purposes if the court rules for the two women. Barnett disputed the 100,000 number.

But Souter said there could easily be 100,000 cancer patients undergoing chemotherapy in California. He said that would undercut Barnett’s argument that the amount of marijuana used for medical purposes would have a “trivial impact” on the market nationwide and on prices.

Justice Stephen Breyer said the two women could have gone to U.S. regulators and asked them to allow the use of medical marijuana. If denied, they then could have sued.

“That seems to me the obvious way to get what they want,” Breyer said. “Medicine by regulation is better than medicine by referendum.” The California law was adopted in a voter referendum in 1996.

Acting Solicitor General Paul Clement, arguing for the government, cited the health dangers from smoking marijuana. “Smoking is harmful,” he said. “It’s true of tobacco, but it’s also true of marijuana.”

He said it would be “very hard” for the government to enforce the nation’s drug laws if an exception was made for medical marijuana.

Justice Sandra Day O’Connor, however, told Clement that two recent Supreme Court’s rulings limiting the reach of Congress’s power to regulate commerce among the states “dictate some concern.”

Plus, the California law involving home-grown marijuana concerned an “area traditionally regulated by the states,” she said.

A ruling in the case is due by the end of June.