Marijuana, if it already wasn’t, is officially mainstream.

Former President Jimmy Carter said he favors legalizing marijuana during a Tuesday appearance on CNN, arguing the federal government should back off and allow states like Washington and Colorado, which legalized the substance by referendum last month, to experiment with regulation.

“I’m in favor of it. I think it’s OK,” Carter said. “I don’t think it’s going to happen in Georgia yet, but I think we can watch and see what happens in the state of Washington, for instance around Seattle, and let the American government and let the American people see, does it cause a serious problem or not.”

Carter has been a longtime proponent of marijuana decriminalization, even calling for it during his presidency as a way to avert unnecessary – and expensive – arrests. Cannabis is currently classified as a Schedule I drug, the most tightly restricted category for drugs that have "no currently accepted medical use." And yet it has been legalized for medicinal use in 18 states.

“When I was president, in 1979 I made my definitive speech about drugs, and I called for the decriminalization of marijuana," he said.  “This was in 1979 — not for the legalization, but the decriminalization, to keep people from being put in prison just because they were smoking a marijuana cigarette."

More than 750,000 people were arrested for a marijuana violation in 2011, 86 percent of them just  for possession, according to the Drug Policy Institute., which favors legalization. Blacks and Hispanics made up two-thirds of the people incarcerated for drug offenses in state prisons that year, even though those groups statistically use and sell drugs at the same rate as whites.

Earlier this year Carter accused U.S. drug policy of having “destroyed the lives of millions of young people” and advocated alternative treatments, such as drug rehabilitation, rather than imprisonment for those “who use drugs but do no harm to others.”