An anonymous reader writes "With the advent of national security letters and all the NSA issues of late perhaps the web needs to implement a warrant 'warrant canary' metatag. Something like this: <meta name="canary" content="2013-11-17" />. With this it would be possible to build into browsers or browser extensions a means of alerting users when a company has in fact received such a secret warrant. (Similar to the actions taken by Apple recently.) The advantage the metatag approach would have its that it would not require the user to search out a report by the company in question but would show the information upon loading of the page. Once the canary metatag was not found or when the date of the canary grows older than a given date a warning could be raised. Several others have proposed similar approaches including Conor Friedersdorf in The Atlantic and Cory Doctorow's Dead Man's Switch." What problems do you see with this approach?