A warrant canary is a method by which a communications service provider aims to implicitly inform its users that the provider has been served with a government subpoena despite legal prohibitions on revealing the existence of the subpoena. The warrant canary typically informs users that there has not been a court-issued subpoena as of a particular date. If the canary is not updated for the period specified by the host or if the warning is removed, users might assume the host has been served with such a subpoena. The intention is for a provider to passively warn users of the existence of a subpoena, albeit violating the spirit of a court order not to do so, while not violating the letter of the order.
Some subpoenas, such as those covered under 18 U.S.C. §2709(c) (enacted as part of the USA Patriot Act), provide criminal penalties for disclosing the existence of the subpoena to any third party, including the service provider's users.[1][2]
National Security Letters (NSL) originated in the 1986 Electronic Communications Privacy Act and originally targeted those suspected of being agents of a foreign power.[3] Targeting agents of a foreign power was revised in the Patriot Act in 2001 to allow NSLs to target those who may have information thought to be relevant to either counterintelligence activities or terrorists activities directed against the United States.[3] The idea of using negative pronouncements to thwart the nondisclosure requirements of court orders and served secret warrants was first proposed by Steven Schear on the cypherpunks mailing list,[4] mainly to uncover targeted individuals at ISPs. It was also suggested for and used by public libraries in 2002 in response to the USA Patriot Act, which could have forced librarians to disclose the circulation history of library patrons.[5][6]
- ^ Nadine Strossen (2005), "Safety and freedom: Common concerns for conservatives, libertarians, and civil libertarians" (PDF), Harvard Journal of Law and Public Policy, vol. 29, no. 73, pp. 78–79, retrieved January 3, 2014
- ^ Eunice Moscoso (August 17, 2003), "Subpoenas Fly In Hunt For Hidden Terrorists", Palm Beach Post, p. 1A
- ^ a b Shaun Waterman (September 30, 2004), "Ashcroft: U.S. will appeal terror-law ruling", United Press International, retrieved January 3, 2014
- ^ "Re: ISP Utility To Cypherpunks? Yahoo! Groups". Tech.groups.yahoo.com. October 31, 2002. Archived from the original on November 3, 2013. Retrieved 2013-06-13.
- ^ West, Jessamyn (2002). "Five Technically Legal Signs for Your Library". Librarian.net : avoiding the PATRIOT Act since 2001. Archived from the original on December 18, 2002. Retrieved 2013-11-14.
{{cite web}}: CS1 maint: unfit URL (link) - ^ Doctorow, Cory (September 9, 2013). "How to foil NSA sabotage: use a dead man's switch - Technology". The Guardian (UK). Retrieved 2013-11-14.