An article in today's Washington Post tells the story of a Maryland couple who, after their home was burglarized, activated a GPS tracking service available from Sprint Nextel (their wireless carrier) and gave assistance to local police to find and arrest the man suspected of robbing them. The alleged burglar stole a cellular telephone belonging to the couple, and (somewhat helpfully it turns out) initiated a pattern of heavy usage of that cell phone within a few hours after he took it. The couple had called Sprint Nextel to report the cell phone stolen, but also inquired whether the carrier had some way to determine the phone's location. Convenient, Sprint Nextel offers a Family Locator service that, among other features, allows subscribers to see real-time GPS location information on web-based satellite maps. Once the couple activated the service, they were able to identify the stolen cell phone's location, and sent copies of the satellite images they viewed on their home computer to the police detective assigned to their robbery case.
Among the more interesting elements in this story is the fact that the couple, as private individuals subscribing to wireless cellular service, were well within their legal rights to track the suspect, his use of their cell phone, and his location while he carried it. This is not the case for the detective investigating the robbery or for law enforcement personnel in general, who are required under state and federal laws either to obtain subpoenas before they can gain access to tracking data. For example, Rule 41 of the Federal Rules of Criminal Procedure, which addresses search and seizure, stipulates specific requirements for law enforcement personnel to obtain a warrant for a tracking device (FRCP Rule 41(e)(2)(C)). Under provisions of the U.S. Code enacted under both the Stored Communications Act (Act) and the Communications Assistance for Law Enforcement Act (CALEA), there are some exceptions to the warrant requirement for obtaining subscriber records from electronic communications service providers like wireless carriers, but where explicit tracking information such as GPS data is concerned, no authoritative precedent has been established as to whether these exceptions apply to cellphone GPS data. The procedures available to law enforcement in 18 U.S.C. §2703(d) relax the standard of evidence required in order to grant a request for disclosure of subscriber record information, where instead of probable cause a government entity need only present "reasonable grounds to believe that the contents of a wire or electronic communication, or the records or other information sought, are relevant and material to an ongoing criminal investigation."
While valid legal avenues do exist for law enforcement personnel to obtain records from wireless carriers such as the GPS location data sought in the Maryland robbery investigation, the process involved takes time, so the immediate access to GPS information that the cell phone subscribers were able to get greatly facilitated the police's ability to find and arrest the suspect. Given how often private citizens are urged not to take the law into their own hands, it is perhaps ironic that the active involvement of the burglary victims in this case was the key to an expedient resolution of the investigation.