The voters of California established a regulatory framework for legalizing medical use of marijuana in 1996 when they approved the Compassionate Use Act (1). California’s law and analogous laws enacted by a significant number of other states (2) are in direct conflict with federal Controlled Substances Act (3). However, the U.S. Department of Justice has promulgated enforcement guidance to the U.S. Attorneys, declining to enforce the federal law against persons who comply with the requirements of state law in the absence of conduct that endangers supreme federal interests identified in the enforcement document, such as interstate distribution of marijuana or sale of marijuana to minors (4).