This week's court decision puts added pressure on Congress to deal with the issue. In writing the court's majority opinion, Associate Justice John Paul Stevens "stressed the need for medical marijuana patients to use the democratic process, putting the ball in Congress's court," says Rob Kampia, executive director of the Marijuana Policy Project in Washington, D.C.
"This is especially important now because next week, the US House of Representatives will vote on an amendment that would prevent the federal government from spending funds to interfere with state medical-marijuana laws," says Mr. Kampia, whose organization provided major funding for the case brought by two California women.
Another question raised by this week's ruling: What lies ahead for Oregon's unique physician-assisted suicide law? The US Justice Department says that law also violates the Controlled Substances Act, and the Supreme Court has agreed to take up the case this fall.
This week's decision also affects a broader debate on the drug. Some advocates had seen medicinal use as a vehicle for building support for marijuana legalization. The Bush administration firmly opposes such a move, and few lawmakers see political advantage in the debate.
But a report out last week estimates that replacing marijuana prohibition with a taxation and regulation system - as exists for alcohol - would produce combined savings and tax revenues of between $10 billion and $14 billion per year.
The report, by Jeffrey Miron, visiting professor of economics at Harvard University, has been endorsed by more than 500 economists, including well-known conservative Milton Friedman of the Hoover Institution at Stanford University.