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. Nevertheless, without federal statutory sanction, more than 20 states have established medical marijuana regulatory regimes. Four have gone further and "legalized" marijuana under state recreational marijuana laws. Because controlled substances classified as Schedule I drugs have "a high potential for abuse" with "no currently accepted medical use in treatment in the United States" and lack "accepted safety for use of the drug [] under medical supervisions," they may not be dispensed under a prescription, and such substances may be used only for bona fide, federal government-approved research studies. Medical Marijuana Laws

State medical marijuana laws follow a general pattern, although most have some individual characteristics and the manner in which they are enforced can differ considerably. In addition, the laws afford registered patients, care givers, cultivators, and distributors immunity from the consequences of state criminal laws. Retail Marijuana

Four states, Washington, Colorado, Oregon, and Alaska, have established retail marijuana regimes. The memorandum instructs federal prosecutors to prioritize their "limited investigative and prosecutorial resources to address the most significant [marijuana-related] threats" and identified the following eight activities as those that the federal government wants most to prevent: (1) distributing marijuana to children; (2) revenue from the sale of marijuana going to criminal enterprises, gangs, and cartels; (3) diverting marijuana from states that have legalized its possession to other states that prohibit it; (4) using state-authorized marijuana activity as a pretext for the trafficking of other illegal drugs; (5) using firearms or violent behavior in the cultivation and distribution of marijuana; (6) exacerbating adverse public health and safety consequences due to marijuana use, including driving while under the influence of marijuana; (7) growing marijuana on the nation's public lands; and (8) possessing or using marijuana on federal property. The preemption doctrine stands at the threshold of the federal-state marijuana debate. The Supremacy Clause, therefore, "elevates" the U.S. Constitution, federal statutes, federal regulations, and treaties above the laws of the states. The MMMA escaped obstacle preemption because it merely conveyed immunity from the consequences of state law: "the MMMA's limited state-law immunity for [medical marijuana] use does not frustrate the CSA's operation nor refuse its provisions their natural effect, such that its purpose cannot otherwise be accomplished.... [T]his immunity does not purport to alter the CSA's federal criminalization of marijuana, or to interfere with or undermine federal enforcement of that prohibition." FinCEN's guidance specifically addresses the obligations to file suspicious activity reports (SARs). FinCEN began its guidance by emphasizing the point made in the accompanying 2014 Cole Memorandum, that the Justice Department's investigation and prosecution of financial crimes would be focused on activities that conflict with any of several federal priorities:
preventing the distribution of marijuana to minors; preventing revenue from the sale of marijuana from going to criminal enterprises, gangs, and cartels; preventing the diversion of marijuana from states where it is legal under state law in some form to other states; preventing state-authorized marijuana activity from being used as a cover or pretext for the trafficking of other illegal drugs or other illegal activity; preventing violence and the use of firearms in cultivation and distribution of marijuana; preventing drugged driving and the exacerbation of other adverse public health consequences associated with marijuana use; preventing the growing of marijuana on public lands and attendant public safety and environmental dangers posed by marijuana production on public lands; and preventing marijuana possession or use on federal property. The offender and any accomplices face an additional five-year mandatory minimum term of imprisonment for possession of a firearm; a seven-year mandatory term if he brandishes the firearm; and a 10-year mandatory term if discharges it. The question of whether marijuana users may be excluded from federally assisted housing is not the same as whether applicants for such housing may be required to undergo drug testing. Lawyers may advise their clients about the features of the state medical marijuana statute, but they may not assist clients in a violation of the CSA. Enacted Marijuana-Related Measures

P.L. However, there is some uncertainty regarding the legal effect of the provision. Legislative Proposals in the 114th Congress

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The federal Controlled Substances Act (CSA) outlaws the possession, cultivation, and distribution of marijuana except for authorized research. More than 20 states have regulatory schemes that allow possession, cultivation, and distribution of marijuana for medicinal purposes. Four have revenue regimes that allow possession, cultivation, and sale generally. The U.S. Constitution's Supremacy Clause preempts any state law that conflicts with federal law. Although there is some division, the majority of state courts have concluded that the federal-state marijuana law conflict does not require preemption of state medical marijuana laws. The legal consequences of a CSA violation, however, remain in place. Nevertheless, current federal criminal enforcement guidelines counsel confining investigations and prosecutions to the most egregious affront to federal interests.
Legal and ethical considerations limit the extent to which an attorney may advise and assist a client intent on participating in his or her state's medical or recreational marijuana system. Bar associations differ on the precise boundaries of those limitations.
State medical marijuana laws grant registered patients, their doctors, and providers immunity from the consequences of state law. The Washington, Colorado, Oregon, and Alaska retail marijuana regimes authorize the commercial exploitation of the marijuana market in small taxable doses.
The present and potential consequences of a CSA violation can be substantial. Cultivation or sale of marijuana on all but the smallest scale invites a five-year mandatory minimum prison term. Revenues and the property used to generate them may merely be awaiting federal collection under federal forfeiture laws. Federal tax laws deny marijuana entrepreneurs the benefits available to other businesses. Banks may afford marijuana merchants financial services only if the bank files a suspicious activity report (SAR) for every marijuana-related transaction that exceeds certain monetary thresholds, and only if it conducts a level of due diligence into its customers' activities sufficient to unearth any affront to federal interests.
Marijuana users may not possess a firearm or ammunition. They may not hold federal security clearances. They may not operate commercial trucks, buses, trains, or planes. Federal contractors and private employers may be free to refuse to hire them and to fire them. If fired, they may be ineligible for unemployment compensation. They may be denied federally assisted housing.
At the heart of the federal-state conflict lies a disagreement over dangers and benefits inherent in marijuana use. The CSA authorizes research on controlled substances, including those in Schedule I such as marijuana, that may address those questions. Members have introduced a number of bills in the 114th Congress that speak to the conflict. Additionally, a few marijuana-related provisions were enacted into law late in the 113th Congress.
This report is an abridged form, without footnotes or citations to authority, of CRS Report R43435, Marijuana: Medical and Retail—Selected Legal Issues, by [author name scrubbed], [author name scrubbed], and [author name scrubbed]. Portions of this report have been borrowed from CRS Report R43034, State Legalization of Recreational Marijuana: Selected Legal Issues, by [author name scrubbed] and [author name scrubbed].