"Even if details leaked by the FBI Director fell under confidentiality obligations, the public's need to know here is the superior obligation," Snowden wrote on Twitter.
Comey acknowledged in a bombshell testimony before the Senate Intelligence Committee earlier Thursday that he had authorized a friend to share with a reporter the content of a personal memo detailing a conversation between him and Trump.
The memo, which Comey wrote contemporaneously, documented his Oval Office meeting with Trump in February when the president allegedly asked him to drop the investigation into former national security adviser Michael Flynn.