[Excerpt] "Federal law makes the cultivation and use of marijuana illegal for all purposes. Yet, over the past two decades, 28 states plus the District of Columbia have legalized marijuana for medicinal purposes, and eight states plus the District of Columbia have legalized it for recreational purposes. Marijuana regulation thus provides a useful and timely example for exploring the ways in which the distribution of power between the federal government and the states can facilitate policy change."
John M. Greabe, Marijuana Regulation and Federalism, Concord Monitor, Mar. 12 2017 at D1, D4.