WASHINGTON — Despite 75 years of federal marijuana prohibition, the Justice Department said Thursday that states can let people use the drug, license people to grow it, and even allow adults to stroll into stores and buy it — as long as pot is kept away from kids, the black market, and federal property.
In a sweeping new policy statement prompted by marijuana legalization votes in Washington and Colorado last fall, the department gave the green light to states to adopt tight regulatory schemes to oversee the medical and recreational marijuana industries burgeoning across the country.
The action, welcomed by supporters of legalization, could set the stage for more states to legalize marijuana. Alaska could vote on the question next year, and a few other states plan similar votes in 2016.
The policy change embraces what Justice Department officials called a ‘‘trust but verify’’ approach between the federal government and states that enact recreational drug use.
In a memo to all 94 US attorneys’ offices across the country, Deputy Attorney General James Cole said the federal government expects states and local governments authorizing ‘‘marijuana-related conduct’’ will implement strong and effective regulatory and enforcement systems that address the threat those state laws could pose to public health and safety.
‘‘If state enforcement efforts are not sufficiently robust . . . the federal government may seek to challenge the regulatory structure itself,’’ the memo stated. States must ensure ‘‘that they do not undermine federal enforcement priorities,’’ it added.
The US attorney in Colorado, John Walsh, said he will continue to focus on whether Colorado’s system has the resources and tools necessary to protect key federal public safety interests.
Colorado Governor John Hickenlooper said the state is working to improve education and prevention efforts directed at young people and on enforcement tools to prevent access to marijuana by those under age 21. Colorado also is determined to keep marijuana businesses from being fronts for criminal enterprises or other illegal activity, he said, and the state is committed to preventing export of marijuana while also taking more steps to keep state roads safe from impaired drivers.
Washington Governor Jay Inslee also laid out guidelines for marijuana entrepreneurs.
‘‘If you don’t sell this product to children, if you keep violent crime away from your business, if you pay your taxes and you don’t use this as a front for illicit activity, we’re going to be able to move forward,’’ Inslee said.