There are 500 registered medicinal users of marijuana in Colorado. They are allowed to grow their own pot (up to six plants) or possess small amounts for their own use, through the good graces of 281 doctors who supported their applications for a state-issued license. Many doctors won’t sign onto an application, not wanting their name linked to marijuana. Many patients don’t apply for the license, either because they don’t want others to know or they don’t realize they need a license. Cultivation of even one plant without a license is a felony under Colorado state law. The U.S. Supreme Court heard arguments yesterday in Ashcroft v. Raich, a case in which it will decide whether the federal government’s interest in regulating drugs trumps states’ rights.

The question before the court is whether individual patients — and, possibly, some of their suppliers — are immune from federal enforcement. The argument goes like this: The Constitution authorizes Congress to regulate interstate commerce. But no interstate commerce is involved when patients, acting legally under state law, use marijuana that was grown within the state and supplied without charge. The counterargument, by the government and its allies, is that all illicit drug use affects interstate commerce. Even freely supplied marijuana boosts the demand for the drug, reduces the overall supply and may affect the price, the government says; in addition, pot looks the same whether it’s grown locally or shipped between states.

I was interviewed for Tuesday’s article in the Rocky Mountain News, and made one more argument for medical marijuana: Human decency and compassion. Marijuana makes life bearable for many suffering pain from a diverse a group of medical conditions, ranging from neuropathic pain (pain from nerve damage) to nausea, spasticity, glaucoma, cancer, HIV/AIDS and movement disorders. In the 21st century, no one should be forced to live in pain.