A fraud case in Arizona has raised the issue: do agents need a warrant to track your location using advanced technologies like the Stingray? The device imitates the behavior of a cell phone tower, allowing it to surreptitiously pinpoint the location of a target's mobile phone. The government argues that the Stingray and like technologies do not require warrants because they are more like pen registers, or trap and trace technology, which do not require warrants, than they are like wiretaps, which do. The case is an important one, and like US v. Jones, a case on warrantless GPS tracking currently before the Supreme Court, it will help shape the future of privacy in the digital age. After all, if the police and FBI can use a Stingray and a GPS device to locate you at home, at the office, at the gym, and at a friend's house without a warrant, what privacy invasive procedures can't they use?
The government's argument seems to suggest that the only thing they need a warrant for is the content of our communications (and until recently not even in all cases). Wiretaps require warrants, it says, but not technologies that pinpoint where we are physically at any given moment. But this line of thinking ignores the fact that by tracking our movements, the government is able to discern a very clear picture of the content of our lives. If our location and our movements are deemed exempt from Fourth Amendment protections, the FBI can very easily -- and without any good reason -- learn the most intimate things about us: whether we are religious, whether we are politically active, whether we love music or animals, whether we have cancer. And not just some such facts about us, but all such facts.
The Arizona fraud case highlights another important issue before our courts: state secrecy. In a predictable twist, the government is refusing to disclose the technological specifications of the tools it used to track down Daniel David Rigmaiden in the Arizona fraud case, arguing that disclosure of their spy tools would harm future investigations. The argument came up because Rigmaiden's lawyers are trying to have the case thrown out on the grounds that the warrant the FBI procured for use of the Stingray (yes, the FBI got a warrant, even though it says it doesn't need one) was a bad warrant. They argue it was a bad warrant because it didn't name the technology the agency would use and allowed the FBI to delete information it gleaned through the process.
Unfortunately, the court agreed with the FBI's assessment about the need to keep secret these tools of the trade. The court wrote that disclosure of government surveillance techniques used against Rigmaiden would “hamper future law enforcement efforts by enabling adversaries of law enforcement to evade detection” and “defeat electronic surveillance operations." Score one for the FBI.
But the fight isn't over yet. Enter the privacy-loving, security-minded technologists.
In a friends of the court brief, a number of technology experts, including Jacob Appelbaum and Christopher Soghoian, have called the government's bluff on the claim that it cannot disclose the tools it used to surveil Mr. Rigmaiden. That's because, they argue, details about these systems are already public. Furthermore, their brief states, the know-how and technological capacity exists to very cheaply and relatively easily build modifications to common cell phones that can detect the usage of IMSI catchers --- the technical name for Stingray-like tools. Furthermore, anyone with an internet connection and $1500 can build their own IMSI catcher, the technologists say.
The government may wish that the public remain in the dark regarding its surveillance of mobile phones using IMSI catchers and specifically, details regarding how such surveillance technology can be detected and thwarted. That genie cannot be put back into the bottle. Detailed information about IMSI catchers, as well as software enabling the detection of such covert surveillance of mobile telephones, is already available to the public and accessible to anyone with access to an Internet search engine.
Finally, the communications privacy of millions of law-abiding Americans is already threatened by the use of this and similar interception technologies by non-US government entities, such as stalkers, criminals, and foreign governments engaged in espionage. As such, the public interest is best served by greater public discussion regarding these tracking technologies and the security flaws in the mobile phone networks that they exploit, not less.