In late December 2015, the Government Accounting Office (GAO) issued a report to Congress recommending that the Department of Justice (DOJ) document a plan specifying its process for monitoring the effects of state marijuana legalization, and share the plan with DOJ components. The DOJ concurred with GAO’s recommendations. Because an increasing number of states have adopted laws that legalize marijuana for medical or recreational purposes (despite the continuing federal penalties), the DOJ has periodically issued guidance regarding criminal enforcement priorities. In 2013, the DOJ updated its marijuana enforcement policy by issuing guidance clarifying federal marijuana enforcement priorities (MEMORANDUM: Guidance Regarding Marijuana Enforcement), which stated that the DOJ may challenge state marijuana legalization systems that threaten the priorities. GAO was then asked to review issues related to Colorado’s and Washington’s actions to regulate recreational marijuana and DOJ’s mechanisms to monitor the effects of state legalization. The resulting GAO report examines, among other issues, the DOJ’s efforts to monitor the effects of state marijuana legalization relative to DOJ’s 2013 guidance and factors DOJ’s field officials reported affecting their marijuana enforcement in selected states with medical marijuana laws. GAO analyzed DOJ’s marijuana enforcement guidance and drug threat assessments, and evaluated DOJ’s monitoring efforts against internal control standards. GAO also interviewed cognizant DOJ officials, including U.S. Attorneys and Drug Enforcement Administration officials in six states. The GAO report found that the DOJ has not documented its monitoring process, as called for in Standards for Internal Control in the Federal Government, which provides the framework for establishing and maintaining internal control in federal agencies. The GAO report concluded that documenting a plan that specifies its monitoring process would provide the DOJ with greater assurance that its monitoring activities relative to DOJ’s marijuana enforcement guidance are occurring as intended. Further, the report notes that making this plan available to appropriate DOJ components can provide the Office of the Deputy Attorney General (ODAG) with an opportunity to gain institutional knowledge with respect to its monitoring plan, including the utility of the data being used. This would better position ODAG to identify state systems that are not effectively protecting federal enforcement priorities and, if necessary, take steps to challenge these systems in accordance with DOJ marijuana enforcement guidance.