By Jonathan Havens, Adam Fayne and Jim Keller (March 26, 2018, 3:24 PM EDT) -- It is hard to turn on the news or read a newspaper these days without being confronted by the rapid expansion of state marijuana programs. More than 50 percent of states currently have medical marijuana laws on their books, several other states are considering establishing such programs, and a handful of states allow adult use of recreational marijuana. While the lists of conditions for which medical marijuana is available in various states have expanded over time, and while the number of states in which marijuana use is authorized has also increased, such developments have not made it easier for college students to use marijuana on campuses....