Voters in Oregon, Alaska and the District of Columbia legalized recreational marijuana yesterday. Twenty-three states have approved it for medical use. But it’s still a prohibited schedule-one drug under federal law, just like heroin, Ecstasy and LSD. In 2016, more states around the country will be voting on various formulas for legalizing it. If they succeed, the pressure will grow on Congress and the next president. Beau Kilmer is co-director of the RAND Drug Policy Research Center and co-author of Marijuana Legalization: What Everyone Needs to Know.