Laws vary by state, though state law is superseded by federal law which classifies cannabis as a Schedule I substance, the same classification as heroin. The United States Supreme Court has ruled in Gonzales v. Raich that the federal government has a right to regulate and criminalize cannabis, even for medical purposes. In 2009 the Attorney General directed federal prosecutors to back away from medical marijuana patients in those states with local laws legalizing medical use.[74]
via en.wikipedia.org
