Cannabis plant. (REUTERS/Alessandro Bianchi)

For decades, Native American reservations have been havens for the gambling industry in states with anti-casino legislatures. Can we count Big Pot in too?

The Justice Department said Thursday it will no longer prosecute federal laws regulating the growing or selling of marijuana on reservations, even when state law bans the drug.

Timothy Purdon, the U.S. attorney for North Dakota and the chairman of the attorney general’s subcommittee on Native American issues, explained to the Los Angeles Times that federal prosecutors will not enforce federal pot laws as long as reservations meet the same guidelines as states that have opted for legalization. He also said the federal government will continue to support any marijuana bans passed by tribal councils, even when the state allows recreational use.

In other words: The government will let tribal governments decide what to do about pot.

The policy was not a result of any particular demand for legalization on reservations. On the contrary: Oregon U.S. Attorney Amanda Marshall told the Associated Press the guidelines are a response to an inquiry from tribal governments wanting to know whether the Department of Justice would back tribal pot bans in states where recreational use is legal — currently Oregon, Washington, Colorado and Alaska.

The United States has 326 federally-recognized reservations, most in states that ban recreational marijuana. But whether reservations will become free zones for the drug depends on the decisions of tribal governments, many of which have struggled against drug and alcohol addiction within their borders.

The Hoopa Valley Tribe in California, for example, has enlisted the help of state police in ridding its ancestral lands of illegal pot grows for years. And the Yakama Nation of Washington, whose tribal lands cover 1.2 million acres, has actively fought statewide legalization, seeking to ban marijuana in all 10 counties of its ancestral lands — about a fifth of the state. As in California, tribal police have spent years chasing growers off of their reservation.

Marshall said only three such tribes —  one in California, one in Washington state and one in the Midwest — have said they’re interested in legalization. She would not disclose which ones.

When asked about any plans to legalize, the Mohegan Tribal Council of Connecticut told the Hartford Courant it is “looking at numerous opportunities to diversify into new emerging markets.”

Tribes must follow the same guidelines laid out for states that have already opted for legalization, according to the Justice Department. Feds say they will step in when pot is sold or given to minors, and when marijuana revenues are benefiting criminal drug cartels or other trafficking activities. Carting marijuana from a legal state to an illegal state is still not allowed.

Up next is how they will be taxed: As states like Colorado see an economic windfall from the newly legal industry along with soaring tax revenues, will reservations try to undercut them, becoming intra-state tax havens for the marijuana industry?