"America has no functioning democracy at this moment," Carter said at a closed-door event in Atlanta covered by a German newsmagazine.
No American outlets covered the event, but the quote published by Der Spiegel is in line with opinions Carter has expressed previously.
In June, just after Snowden became trapped in Moscow's Sheremetyevo International Airport transit zone, Carter described the intelligence leak as "beneficial."
"He's obviously violated the laws of America, for which he's responsible, but I think the invasion of human rights and American privacy has gone too far," he told CNN. "I think that the secrecy that has been surrounding this invasion of privacy has been excessive, so I think that the bringing of it to the public notice has probably been, in the long term, beneficial."
He added that nations were within their rights to offer Snowden asylum.
Snowden requested temporary asylum in Russia until he can reach Latin America safely, where Bolivia, Venezuela, and -- "if circumstances permit" -- Nicaragua have extended offers of asylum.
Snowden's lawyer said Wednesday that he will leave the airport within the "next few days" with a certificate showing that a request for temporary asylum in Russia is under consideration, allowing Snowden to legally leave the airport's transit area.
The U.S. government has requested Russia expel Snowden. It's not clear whether Russia will decide to grant temporary asylum, and a decision could take weeks.
On Wednesday, Russian President Vladimir Putin told reporters that ties between the U.S and Russia "are far more important" than an intelligence scandal.