Although some states have legalized the medical use of marihuana, the federal government can still ban possession of the drug in states. While federal law does not overturn state laws legalizing medical marihuana use, those who try to use marijuana as a medical treatment risk legal action by the U.S. Drug Enforcement Administration or other federal agencies.
In the landmark case of Gonzales v. Raich, 545 U.S. 1 (U.S. 2005), the United States Supreme Court held that the federal government has the constitutional authority to prohibit marijuana for all purposes. In Gonzales, respondents were California residents who used marijuana to treat serious medical conditions. They used marijuana pursuant to the terms of the Compassionate Use Act, Cal. Health & Safety Code § 11362.5 (2005). The federal agents seized and destroyed the cannabis plants cultivated for home consumption. The Court held that the regulation of marijuana under the CSA was within Congress’ commerce power because production of marijuana meant for home consumption had a substantial effect on supply and demand in the national market. Thus, federal law enforcement officials may prosecute medical marijuana patients, even if they grow their own medicine and even if they reside in a state where medical marijuana use is protected under state law. Therefore, whenever, there is a difference between the federal and state laws, the federal laws prevail.