Opening the door for what could be a lucrative and controversial new industry on some Native American reservations, the Justice Department on Thursday told U.S. attorneys to not prevent tribes from growing or selling marijuana on the sovereign lands, even in states that ban the practice, reports the Los Angeles Times.

The new guidance, released in a memorandum, will be implemented on a case-by-case basis and tribes must still follow federal guidelines, said Timothy Purdon, the U.S. attorney for North Dakota and the chairman of the Attorney General's Subcommittee on Native American Issues.

It remains to be seen how many reservations will take advantage of the policy. Many tribes are opposed to legalizing pot on their lands, and federal officials will continue to enforce the law in those areas, if requested.