Three more states legalized marijuana for recreational or medical use on Tuesday. In both Utah and Missouri, voters legalized marijuana for medical purposes â the 31st and 32nd states to approve medical cannabis. Under the measure, adults can be in possession of 2.5 ounces of marijuana, a provision similar to the stateâs medical marijuana law that was approved in 2008. Amendment 2 legalized medical marijuana and imposes a 4 percent tax on all marijuana sales. In October, Utah medical marijuana advocates and state lawmakers agreed to a compromise bill that would legalize medical marijuana in the state but with some differences from the ballot initiative.