"Many in the media have tried to spin this as not a “leak” because leaks by definition only involve classified information. That is entirely untrue as shown by history. Leaks involve the release of unauthorized information — not only classified information. Many of the most important leaks historically have involved pictures and facts not classified but embarrassing to a government. More importantly, federal regulations refer to unauthorized disclosures not just classified information."
"Besides being subject to nondisclosure agreements, Comey falls under federal laws governing the disclosure of classified and unclassified information. Assuming that the memos were not classified (though it seems odd that it would not be classified even on the confidential level), there is 18 U.S.C. § 641, which makes it a crime to steal, sell, or convey “any record, voucher, money, or thing of value of the United States or of any department or agency thereof.”
Jonathan Turley really lays it out.