There is no law that categorically prohibits all leaks of classified (or unclassified) information. Instead, there is a patchwork of statutes that outlaw some unauthorized disclosures under some circumstances.
The various statutes that have been used to punish leaks of classified information are surveyed in a new publication from the Congressional Research Service. See The Law and Leaks to the Press, CRS Legal Sidebar, February 22, 2017.
“Not every leak to the press is a federal crime,” CRS notes. Even when a disclosure is a potential crime, the underlying statutes are not self-activating or self-enforcing. Investigators and prosecutors retain considerable discretion about how to proceed.
I discussed some of these issues lately in the Washington Post. See “President Trump’s war on leaks, explained” by Aaron Blake, February 16.
Other noteworthy new or updated reports from the Congressional Research Service include the following.
A New Authorization for Use of Military Force Against the Islamic State: Issues and Current Proposals, updated February 21, 2017
Iran’s Nuclear Program: Tehran’s Compliance with International Obligations, updated February 23, 2017
Federal Building and Facility Security: Frequently Asked Questions, updated February 22, 2017
U.S. Secret Service: Selected Issues and Executive and Congressional Responses, updated February 22, 2017
“Dear Colleague” Letters in the House of Representatives: Past Practices and Issues for Congress, February 22, 2017
Health Care-Related Expiring Provisions of the 115th Congress, First Session, updated February 22, 2017
El Salvador: Background and U.S. Relations, updated February 23, 2017
The North American Free Trade Agreement (NAFTA), updated February 22, 2017