Devices that Track Cell Phone Signals Violate Fourth Amendment, Say Privacy Advocates

Less than a century ago, the simplest way to spy on someone’s communications was to intercept and read their mail. The means of communication have changed since then, but so has law enforcement. A sophisticated technology known as international mobile subscriber identity locators, or “IMSI catchers,” can track wireless communications and locate mobile devices. Privacy advocates and criminal defendants are now pushing back against overreaching by law enforcement, since IMSI catchers can locate an individual suspect and every other nearby mobile device user. Courts remain divided on how to view IMSI catchers under the Fourth Amendment. Recent Supreme Court cases have applied strict limits on how police may use GPS tracking devices and infrared surveillance, and IMSI catchers may come under their review soon.

A popular brand of IMSI catcher among law enforcement is called the Stingray. By mimicking a cellphone tower, it tricks nearby mobile devices into sending it signals. This allows the device to identify every mobile device within range, determine their locations, and track incoming and outgoing calls. It can record the content of phone conversations on some devices. The government has reportedly gone to great lengths to avoid disclosing the details of its use of the Stingray, leading groups like the Electronic Frontier Foundation (EFF) and the American Civil Liberties Union (ACLU) to campaign for transparency.

A current federal criminal case in Arizona, United States v. Rigmaiden, No. 2:08-cr-00814, is the scene of a showdown between privacy advocates and the government over the Stingray. According to the EFF, a federal judge in California ordered Verizon to help law enforcement find the defendant, Daniel Rigmaiden, by providing the location of a cellphone believed to belong to him. The government, the EFF says, then conducted their own investigation using a Stingray without Verizon’s direct involvement. The Stingray located the defendant, but also exposed every other mobile device user in the area. In an amicus brief filed in support of Rigmaiden, the EFF and the ACLU argued that the use of the Stingray exceeded the scope of the court’s order, and amounted to a warrantless search in violation of the Fourth Amendment. The EFF compares the practice to the searches of private homes conducted with impunity by British soldiers during the Colonial era.

A federal magistrate judge in Corpus Christi, Texas, Brian L. Owsley, has questioned the use of devices like the Stingray, noting that law enforcement does not provide details in its applications for warrants about how it will use the device. He has also stated that special agents and prosecutors do not seem to have much understanding of how the technology works, and therefore cannot appreciate the broader implications for innocent cellphone users. He described a request for a several warrants as “a very broad and invasive search affecting likely hundreds of individuals in violation of the Fourth Amendment.” In re U.S. ex rel Order Pursuant to 18 U.S.C. ยง 2703(d), 2012 WL 4717778, *4 (S.D. Tex., Sep. 26, 2012). Judge Owsley denied the applications for cell site data in that case, holding that such information is protected by the Fourth Amendment. Id. at *3.

Michael J. Brown, a board-certified criminal defense attorney, fights for the rights of Texas defendants, making certain that law enforcement and the courts abide by all the rules and procedures of the criminal justice system. To learn more about how we can assist you in your legal matter, contact us online or at (432) 687-5157.

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