"Federal law classifies marijuana as a Schedule I Controlled Substance. As a result, it is a federal crime to grow, sell, or merely possess the drug. In addition to facing the prospect of a federal criminal prosecution, those who violate the federal Controlled Substances Act (CSA) may suffer a number of additional adverse consequences under federal law. For example, federal authorities may confiscate any property used to grow marijuana or facilitate its sale or use; marijuana users may lose their jobs, their homes, or their right to possess a firearm or ammunition; and sellers of marijuana may lose the tax benefits and banking services that other merchants enjoy, and ultimately their businesses. Nevertheless, without federal statutory sanction, 20 states have established medical marijuana regulatory regimes. Two have gone further and 'legalized' marijuana under state recreational marijuana laws. State officials lack the constitutional authority necessary to trump conflicting federal law. Federal officials, however, lack the unlimited resources necessary to trump the impact of conflicting state law. The following is an analysis of some of the legal issues the situation has generated and some of the proposals to resolve them."
CRS Report for Congress, R43435
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html