[JURIST] A three-judge panel for the US Court of Appeals for the Third Circuit [official website] ruled [opinion, PDF] Tuesday that at times the government might need a warrant to obtain cell phone data to track a person’s location. The ruling reversed a decision [order, PDF] by US Magistrate Judge Lisa Pupo Lenihan of the US District Court for the Western District of Pennsylvania [official website], which said that that § 2703 of the Stored Communications Act (SCA) [text] does not authorize the government to obtain cell site location information (CSLI) and that prosecutors must always show probable cause to access CSLI at the risk of violating a cell phone users’ Fourth Amendment [text] rights. Writing for the appeals court, Judge Delores Sloviter remanded the order to the magistrate judge for further proceedings, while stating that the SCA gives judges the discretion to require a warrant when the government seeks CSLI. The court held that:

CSLI from cell phone calls is obtainable under a § 2703(d) order and … such an order does not require the traditional probable cause determination. … The [magistrate judge] erred in allowing her impressions of the general expectation of privacy of citizens to transform that standard into anything else. We also conclude that this standard is a lesser one than probable cause. … Because the statute as presently written gives the [magistrate judge] the option to require a warrant showing probable cause, we are unwilling to remove that option although it is an option to be used sparingly because Congress also included the option of a § 2703(d) order. However, should the [magistrate judge] conclude that a warrant is required rather than a § 2703(d) order, on remand it is imperative that the [magistrate judge] make fact findings and give a full explanation that balances the Governments need (not merely desire) for the information with the privacy interests of cell phone users.

The court’s reasoning closely followed amicus briefs [text, PDF] filed by the American Civil Liberties Union, the Electronic Frontier Foundation and the Center for Democracy and Technology [advocacy websites] opposing the gathering of CSLI, finding that “cell phone customer[s] [have] not “voluntarily” shared [their] location information with a cellular provider[s],” giving up their Fourth Amendment rights.

Courts have struggled with how to apply Fourth Amendment protections to modern technology. In August, the US Court of Appeals for the District of Columbia Circuit [official website] ruled [opinion, PDF; JURIST report] that prolonged use of global positioning systems (GPS) to monitor suspects’ vehicles violates the Fourth Amendment protection against unreasonable searches and seizures. Although the Supreme Court’s ruling in United States v. Knotts [opinion text] allows the use of tracking devices to follow vehicles from one place to another based on a lower expectation of privacy on public roads, the appeals court distinguished the instant case by finding that too much personal information is revealed over longer periods of time. In June, the US Supreme Court [official website] unanimously held [opinion, PDF; JURIST report] that, even if there is a reasonable expectation of privacy in work-issued electronic devices, that an employer’s search of private text messages does not violate the Fourth Amendment so long as the search is not excessive and is pursuant to a legitimate work-related purpose. In 2009, the Ohio Supreme Court [official website] ruled [opinion, PDF; JURIST report] that police must obtain a warrant before searching data stored in a cell phone. In 2005, a federal court in Maryland ruled [opinion, PDF; JURIST report] that US law enforcement agents must obtain a warrant before obtaining information from a cell phone service on the location of a cell phone user. The court noted that although the Fourth Amendment does not protect cell phone users who use their phones in public, probable cause is still required because the individual targeted by the search may use the phone from their home, which has clearly established Fourth Amendment protections.