On Dec. 15, 2016, The Regulation and Taxation of Marijuana Act ("the Act") began to take effect in Massachusetts. It is now legal, under state law, for adults 21 years of age or older to possess and use recreational marijuana under certain restrictions. To date, voters in eight states and Washington, D.C., have passed ballot initiatives allowing for recreational use of marijuana. Twenty-one additional states have passed laws that will allow individuals to use marijuana for medicinal purposes. Looking at how other jurisdictions have interpreted employers' rights under similar laws, we can make some educated predictions on how this new law will impact Massachusetts employers.