In early 2015, Reddit published a transparency report that contained heading for National Security Requests, noting, "As of January 29, 2015, reddit has never received a National Security Letter, an order under the Foreign Intelligence Surveillance Act, or any other classified request for user information."
Five hours ago, Reddit published its 2015 edition, which contains no mention of classified requests for user information.
"Warrant canaries" are a response to the practice by governments of serving warrants on service providers that include gag orders forbidding the service from disclosing the warrant's existence. By publishing regular transparency reports listing the number of secret warrants received to date as "0," then omitting the section dealing with those warrants once the first warrant has been served, companies can create a kind of dead man's switch — done right, it might even stop governments from even trying to serve a warrant (except in Australia, where warrant canaries are illegal).
Reddit had a national security warrant canary in 2015. It's gone now
Reddit admin, answering q's about new transparency report, says he has been told not to comment on the dead canary. https://t.co/wLnndouzNL
— Christopher Soghoian (@csoghoian) March 31, 2016