Marijuana is the most commonly used illicit drug in the United States. In 2013, an estimated 19.8 million individuals in the United States aged 12 or older (7.5% of this population) had used marijuana in the past month. While reported marijuana use is similar to that in 2012, it has generally increased since 2007 when 5.8% of individuals aged 12 or older were current users of marijuana. Mirroring this increase in use, marijuana availability in the United States has also increased. This growth has been linked to factors such as rising marijuana production in Mexico, and increasing marijuana cultivation in the United States led by criminal networks including Mexican drug trafficking organizations. Along with the uptick in the availability and use of marijuana in the United States, there has been a general shift in public attitudes toward the substance. In 1969, 12% of the surveyed population supported legalizing marijuana; today, more than half (52%) of surveyed adults have expressed opinions that marijuana should be legalized. And, 60% indicate that the federal government should not enforce its marijuana laws in states that allow the use of marijuana. The federal government-through the Controlled Substances Act (CSA; P.L. 91-513; 21 U.S.C. 801 et. seq.)-prohibits the manufacture, distribution, dispensation, and possession of marijuana. Over the last few decades, some states have deviated from an across-the-board prohibition of marijuana. Evolving state-level positions on marijuana include decriminalization initiatives, legal exceptions for medical use, and legalization of certain quantities for recreational use. Notably, in the November 2012 elections, voters in Washington State and Colorado voted to legalize, regulate, and tax the recreational use of small amounts of marijuana. In the November 2014 elections, legalization initiatives passed in Alaska, Oregon, and the District of Columbia, further spreading the discrepancy between federal and state marijuana laws in the United States. These latest moves have spurred a number of questions regarding their potential implications for related federal law enforcement activities and for the nation's drug policies on the whole. Among these questions is whether or to what extent state initiatives to decriminalize or legalize the use of marijuana conflict with federal law. In general, federal law enforcement has tailored its efforts to target criminal networks rather than individual criminals; its stance regarding marijuana offenders appears consistent with this position. While drug-related investigations and prosecutions remain a priority for federal law enforcement, the Obama Administration has suggested that efforts will be harnessed against large-scale trafficking organizations rather than on recreational users of marijuana. In an August 2013 memorandum, Deputy Attorney General Cole stated that while marijuana remains an illegal substance under the Controlled Substances Act, the Department of Justice would focus its resources on the "most significant threats in the most effective, consistent, and rational way." The memo outlined eight enforcement priorities including preventing the distribution of marijuana to minors and preventing the diversion of marijuana from states where it is legal under state law into other states. It is unclear whether or how the Department of Justice is tracking activity to ensure that federal enforcement priorities are being followed in states that have legalized marijuana.