In 1996, California legalized the medical use of marijuana, even though it was still illegal under federal law. Californians Brad and Diane Monson used homegrown medical marijuana. When federal agents destroyed their plants, the couple sued, claiming, among other things, that the Commerce Clause did not permit the federal government to regulate activities that took place in their backyard and homes. The federal government argued that since consuming locally-grown marijuana for medical purposes affects the interstate market for marijuana, the federal government may regulate - and prohibit - such consumptions.