Canaries can be useful creatures. Coal miners used to bring them into the mines as a warning sign of methane or carbon monoxide. A dead canary meant the miners needed to get out of there pronto.
Now a clever loophole in the rules regarding NSA requests for information is letting companies warn their customers in the same way a little yellow bird might signal trouble.
It's called a "warrant canary", and several major companies like Apple have already used it in their "transparency reports."
The idea is that while the NSA can enforce rules on companies to not tell their customers when their information has been acquired, it is still within a company's rights to tell their customers what they haven't been asked. If a transparency report gets released without a statement saying that the NSA has not requested information, then a customer can infer that the request has been made.
The idea originated from a public library that posted a sign on its door each day saying that the Government had not yet asked for any information on the patrons. The insinuation was that if ever the library did not post the sign, it meant that the NSA had made a request.
According to Jonathan Zittrain, Professor of Law at Harvard and co-founder of the Berkman Center for Internet and Society, it's not only a clever way to let customers know if their information may have been acquired by the NSA, but also a way for the private sector to agitate Government agencies on the issues involved in privacy.
"To mix my fowl, it’s a game of chicken played with a warrant canary. Under the first amendment, it may well be much more dicey for the government to insist that a company lie rather than to tell a company it may not speak."