U.S. Attorney General Jeff Sessions is indicating that he might keep Obama-era marijuana enforcement guidelines in place, perhaps with some modifications.

"The Cole Memorandum set up some policies under President Obama's Department of Justice about how cases should be selected in those states and what would be appropriate for federal prosecution, much of which I think is valid," he said in a question-and-answer session with reporters on Wednesday following a speech in Richmond, Virginia.

That memo, adopted in 2013, lays out guidelines for how states can avoid federal interference with their marijuana laws.

Sessions added that he "may have some different ideas myself in addition to that" but indicated that the federal government would not be able to enforce its remaining marijuana prohibition laws across the board in states with legalization.

"Essentially we’re not able to go into a state and pick up the work that the police and sheriffs have been doing for decades," he said.

The attorney general also addressed medical cannabis, suggesting that it "has been hyped, maybe too much."

"It's possible that some dosages can be constructed in a way that might be beneficial," he said. "But if you ever just smoke marijuana for example where you have no idea how much THC you're getting it's probably not a good way to administer a medicinal amount. So, forgive me if I'm a bit dubious about that."

In the speech before taking questions from reporters, Sessions acknowledged that marijuana isn't as harmful as heroin, something that Justice Department officials have been reluctant to do in the past:

"I realize this may be an unfashionable belief in a time of growing tolerance of drug use. But too many lives are at stake to worry about being fashionable. I reject the idea that America will be a better place if marijuana is sold in every corner store. And I am astonished to hear people suggest that we can solve our heroin crisis by legalizing marijuana – so people can trade one life-wrecking dependency for another that’s only slightly less awful. Our nation needs to say clearly once again that using drugs will destroy your life."

During his Senate Judiciary Committee confirmation hearing in January, Sessions called the Obama-era Cole memo "valuable" but suggested that he thought its provisions might not have been enforced strictly enough under the prior administration.

In a radio interview last week, he admitted that "it’s not possible for the federal government, of course, to take over everything the local police used to do in a state that’s legalized it."

As a Republican senator representing Alabama, Sessions was long one of Congress's most ardent proponent of the war on drugs. Last year, he said that "good people don't smoke marijuana."