What happened
Reddit's first transparency report, published in early 2015, included a carefully worded paragraph that functioned as a 'warrant canary.' It stated that as of January 29, 2015, Reddit had never received a national security letter, an order under the Foreign Intelligence Surveillance Act, or any other classified request for user information, and it promised that if such a request ever arrived, the company would seek to let the public know.
A warrant canary is a legal workaround for secret surveillance orders, which typically carry gag provisions that bar a company from confirming their existence. By affirmatively stating that no such order had been received, Reddit created a signal that could be removed later, since deleting the statement would not technically violate a gag order. The canary placed Reddit among a small group of technology firms using the technique to push back against secret data demands, and it set up a closely watched test of whether the company would be able to keep the language in place.