First, a new constitutional amendment, CI-118, lets the legislature or a ballot initiative set a legal age for marijuana use.
Second, a statutory measure, I-190, allows for marijuana possession, use, and growing among adults 21 and older. It also puts the state Department of Revenue in charge of setting up and regulating a commercial system for growing and selling cannabis, imposes a 20 percent tax on sales, and allows local governments to ban cannabis businesses within their borders. Finally, it allows people convicted of past marijuana crimes to seek resentencing or expungement.
Montana already allowed marijuana use for medical purposes. The new law expands legalization to recreational and other nonmedical uses.
Marijuana remains illegal under federal law. But starting with President Barack Obama’s administration, the federal government has generally allowed states to legalize cannabis with minimal federal interference.
Before Election Day, 11 states and Washington, DC, had legalized marijuana, although DC doesn’t allow recreational sales. Change has moved quickly across the US: A decade ago, zero states allowed marijuana for recreational purposes.
Supporters of legalization argue that it eliminates the harms of marijuana prohibition: the hundreds of thousands of arrests around the US, the racial disparities behind those arrests, and the billions of dollars that flow from the black market for illicit marijuana to drug cartels that then use the money for violent operations around the world. All of this, legalization advocates say, will outweigh any of the potential downsides — such as increased cannabis use — that might come with legalization.
Opponents, meanwhile, claim that legalization will create a huge marijuana industry that will market the drug irresponsibly. They point to America’s experiences with the alcohol and tobacco industries in particular, which have built their financial empires in large part on the backs of the heaviest consumers of their products. And they argue ending prohibition could result in far more people using pot, potentially leading to unforeseen negative health consequences.
In Montana, voters have sided with legalization supporters.
For more on the debate over marijuana legalization, read Vox’s explainer.