This brief article explains the Supremacy Clause of the United States Constitution and how it affects the discrepancy between cannabis laws at the state and federal levels.

This essay from Professor Gary Lawson explains the history and significance of the Supremacy Clause of the United States Constitution.

Stanford Law Professor Robert MacCoun discusses the Department of Justice memos regarding the enforcement of marijuana laws and explains what they mean in easy-to-understand terms.

In 2018, the Department of Justice issued a statement rescinding the previous DOJ memo which established guidelines for the the federal marijuana enforcement policy. This memorandum requires U.S. Attorneys to enforce the laws enacted by Congress, a departure from the previous policy that enumerated enforcement priorities but required stringent regulation from states that legalized cannabis use.

In light of the decriminalization of marijuana in some states, the Department of Justice issued a statement in 2013, often referred to as "the Cole memo," clarifying their approach to enforcement. In this statement, they identify several enforcement areas that federal law enforcement will continue to pursue, while making it clear that states in which cannabis use is legal are responsible for establishing strict regulatory systems.

The Transportation Security Administration recently updated its policy regarding screening procedures. Safety, rather than searches for illegal drugs, is their priority, but they will refer criminal violations to law enforcement.