Updated

The Justice Department said Thursday it would not challenge state laws in Colorado and Washington that allow for the medical and recreational use of marijuana as long as drug sales don’t conflict with a set of new federal enforcement policies.

The eight new enforcement policies range from preventing the distribution of marijuana to minors to preventing sales revenue from going to criminal enterprises, gangs and cartels. They also aim to prevent the diversion of marijuana outside of states where it is legal under state law.

Thursday’s announcement follows comments President Obama made in December, when he said it does not make sense for the federal government to go after recreational drug users in a state that has legalized recreational use of small amounts of marijuana.

States that had effectively legalized marijuana had been awaiting the guidance from the Justice Department.

Colorado Gov. John Hickenlooper said he understands how difficult the issue has been for federal officials.

"Today's announcement shows the federal government is respecting the will of Colorado voters," he said in a statement.

Other top-priority enforcement areas include stopping state-authorized marijuana activity from being used as a cover for trafficking other illegal drugs and preventing violence and the use of firearms in the cultivation and distribution of marijuana.

The announcement follows last year's first-in-the-nation legalization of recreational marijuana use by Colorado and Washington. In the aftermath of the moves by the two states, Attorney General Eric Holder launched a review of marijuana enforcement policy. The issue was whether the states should be blocked from operating marijuana markets on the grounds that actively regulating an illegal substance conflicts with federal drug law that bans it.

A Pew Research Center poll in March found that 60 percent of Americans think the federal government shouldn't enforce federal anti-marijuana laws in states where its use has been approved. Younger people, who tend to vote more Democratic, are especially prone to that view. But opponents are worried these moves will lead to more use by young people. Colorado and Washington were states that helped re-elect Obama.

Dan Riffle of the Marijuana Policy Project, the nation's largest marijuana policy organization, called the policy change "a major and historic step toward ending marijuana prohibition" and "a clear signal that states are free to determine their own policies."

Kevin Sabet, the director of Project Smart Approaches to Marijuana, an anti-legalization group, predicted the new Justice Department policy will accelerate a national discussion about legalization because people will see its harms -- including more drugged driving and higher high school dropout rates.

The Associated Press contributed to this report.