What Is a Warrant Canary?

A warrant canary is a method of negative speech, through which a website or company can inform its users that they have complied with a gagging court order to hand over user data. A canary must be prepared in advance, as it relies on the company no longer saying that it has not complied with such a warrant.

Tip: Search warrants issued to service providers are often combined with gag orders that prevent the company from informing its users of the warrant. The purpose of this is to allow law enforcement time to build a case against the suspects without alerting them.

In some countries, a court can legally compel you to not say something, such as “we’ve handed over data”, through the use of a gag order. A warrant canary is designed to get around this requirement, through the generally untested legal assumption that the court can’t compel you to actually say something, such as “we haven’t handed over any data”. As such, if and when a court order demanding the submission of user data is complied with, the company can remove or stop updating their canary.

There are two general types of warrant canaries, active removal and passive abandon. In the active removal case, the canary is removed from the website or transparency report. With passive abandon canaries, the canary is supposed to be periodically updated to confirm that no warrants have been received. The lack of canary or updates to the warrant canary indicate the existence of a warrant.

Origin of the term

The name comes from an old early warning method used to test for bad air in mines.

Tip: “Bad air” refers to any combination of lack of oxygen, poisonous gases, and other generally odorless killers.

Miners used to take a birdcage with a healthy and fed canary down into the mine. If the air in the mine was bad, then the smaller canary would suffer the effects and potentially die before the miners did, ideally allowing the miners enough time to escape alive safely. Though cruel to the poor birds, this was a safety measure used long before devices existed that could check for air contamination.

Similarly, a warrant canary is designed to act as a warning about the existence of unseen warrants.

Are warrant canaries legal?

While the concept of the warrant canary appears sound, in reality, there is little clarity about the actual legality of attempting to use one to bypass a legally issued gagging order. While the concept of a gag order is generally well tested and understood, it is less clear if courts can force companies or individuals to explicitly say something. It’s entirely possible that there are legal cases past and present where companies are being instructed to maintain their warrant canaries, either with or without legal challenge.

Legal, computer security, and privacy experts have suggested that the activation of a warrant canary would almost certainly be frowned upon by a court potentially leading to other legal charges such as “contempt”. Specifically, in the US, legal precedents in other free speech cases imply that neither individuals, companies, nor the press can be compelled by the government to say something they don’t want to say. This has not been legally tested in regard to warrant canaries, however, so the legal situation remains unclear.

In a similar legal scenario, due to the since amended US Patriot Act, some US libraries placed a physical warrant canary sign. The warrant canary declared that the FBI hadn’t demanded the submission of any documents from them under the Patriot Act. Similarly, though, the use of these warrant canaries was not legally challenged, so no legal precedents exist.