Page 5 Spring/Summer 2017 The laws and regulations on cannabis have long been a source of contention in the United States. This article details the development of the federal prohibition on cannabis and the gradual le- gal and public policy changes as many states have moved to de-criminalize and legalize medical use of cannabis and, more recently, non-medical adult usage. Significantly, on the federal level, the new administration may signal a shift in federal enforcement policy. The new head of the Department of Justice, Attorney General Jeff Sessions, is a long- standing advocate of strict enforcement of the federal prohibition on cannabis, in- cluding intervention on the state level in contravention of state laws. Meanwhile, the momentum on the state level continues to build towards ac- ceptance of medical cannabis usage and in a number of states more recently — the legaliza- tion of non-medical adult usage. This article will outline the unique issues of fed- eralism presented by cannabis regulations, the extent to which differences between federal and state law on cannabis can be reconciled, and the conflicts and challenges that remain under the current legal landscape. Federal Cannabis Law The period of modern federal regulation1 of can- nabis had its start in 1969 when Congress passed the Controlled Substances Act (CSA). Under the CSA, marijuana is classified as a Schedule I prohibited drug. This categorization under the Act means that marijuana has a high potential for being abused and there is no accepted use whether under medical supervi- sion or not.2 In 2005, the CSA’s constitutionali- ty was challenged when two Californians who were abiding by California’s Compassionate Use Act (discussed below) had their home- grown cannabis destroyed by the Drug En- forcement Agency (DEA).3 The Supreme Court held that under the Commerce Clause of the U.S. Constitution, it is within the federal gov- ernment’s power to regulate even state-legal homegrown cannabis, as cannabis has the abil- ity to substantially affect economic activity.4 The ruling also had another effect. It essential- ly said that even if a state has some sort of medical use exception, the federal government is still free to prosecute those abiding by state laws. Preemption and California’s Compassion- ate Use Act California was the first state to create an ex- ception to the federal prohibition on cannabis by passing the Compassionate Use Act (“CUA”). The purpose of the CUA was “to en- sure that seriously ill Californians have the right to obtain and use marijuana for medical purposes where that medical use is deemed appropriate and has been recommended by a physician who has determined that the per- son’s health would benefit from the use of ma- rijuana . . . .”5 In addition, the Act sought “to ensure that patients who obtained a recom- mendation and primary caregivers would not be subject to sanctions and criminal prosecu- tions.”6 The California exception directly conflicted with federal law. So, how does California’s law, The Intersection of Federal and State Law on Cannabis Regulations: Latest Developments in a Rapidly Shifting Landscape By Andrea Ruth Bird, Jonathan S. Landis, and Alex Avakian*