The American Civil Liberties Union (ACLU) [advocacy website] announced on Wednesday that their affiliates are sending approximately 375 requests for information in 31 states to reveal how law enforcement uses location data tracking on cell phones [press release]. Smartphones now come with built-in global positioning systems (GPS), allowing users' movements to be tracked by law enforcement agencies, sometimes prior to having the phone in custody. But the extent that police are practicing this remains uncertain. Most jurisdictions have never encountered cell phone tracking as a legal question, so police are generally not required to obtain a warrant. The ACLU is demanding a review of information from each targeted department, including: if probable cause warrants are obtained to access cell phone location data, statistics on how frequently law enforcement gathers this data, how much money is being spent on cell phone tracking, and any other policies or procedures used to acquire cell phone location data. The ACLU also supports the Geolocation Privacy and Surveillance Act [materials], introduced to Congress in June, which would require government agencies to obtain a probable cause warrant before seeking location data.
As cell phones become more prevalent in society, they have become a tool for law enforcement officers to track or identify suspects. In January, the Supreme Court of California [official website] ruled [opinion, PDF] that law enforcement officers can legally search text messages [JURIST report] on a suspect's cell phone without a warrant incident to a lawful custodial arrest. The court held 5-2 that a search of the defendant's cell phone text messages in the police station 90 minutes after the arrest did not violate the Fourth Amendment [text] prohibition against unreasonable search and seizure without exigent circumstances. However, the California decision represents a split from the US Court of Appeals for the Third Circuit [official website] 2010 ruling and a 2009 decision [JURST reports] by the Ohio Supreme Court [official website] that both held that police must obtain a warrant before searching data stored on a cell phone. In June 2010, the US Supreme Court ruled [opinion, PDF; JURIST report] unanimously in City of Ontario v. Quon [Cornell LII backgrounder] that an employer's search of private text messages on a work-issued device does not violate the Fourth Amendment if the search is motivated by a legitimate work-related purpose and is not excessive in scope.