Foreign Policy just published this article on the troubling use of informants in domestic counter-terrorism: Does the FBI Have an Informant Problem? The piece analyzes the large challenges of using unregulated criminal informants to do law enforcement work, and discusses a series of recent examples. From the article:
Professional informants are paid by law enforcement to infiltrate criminal or extremist circles, sometimes on a full-time basis. Yet they’re not considered employees of the government and are not subject to the same rules. From warrantless searches to sex with targets to constructing terrorist plots out of thin air, the informant problem is not new, but this powerful investigative tool is under pressure like never before after being exposed to the harsh light of day in a series of recent terrorism trials. Growing media scrutiny and a pending civil lawsuit in California are aggressively challenging whether the benefits of aggressive informant tactics outweigh the risk to civil liberties and are raising troubling questions about the legitimacy of terrorism investigations