A number of courts have considered whether the Fourth Amendment requires the government to obtain a warrant to access historical and/or real time cell phone geographic location information, known as CSLI. CSLI is cell site location data your cell phone gives off when you place or receive a call. Additionally, cell phones also automatically generate location data by continually identifying themselves to the closest cell tower even when there is no live call, and some experts say, even if the cell phone is powered off.

Law enforcement views CSLI as vital to locate and track suspects as part of an criminal investigation, and often seeks the information by filing an application with the relevant court simply stating that the information to be obtained is relevant to an ongoing investigation. The applications may or may not include facts establishing probable cause or even distinguish between location information in either historical or real time. Some court orders granting access do not distinguish between historical or real time data.

Court decisions have been divided on whether probable cause and a warrant is required to obtain CSLI.  Last week, a United States District Judge in the United States District Court for the Northern District of California, San Jose division affirmed the judge magistrate’s ruling denying the government’s application for CSLI on the grounds that a warrant was required to obtain such information. Also earlier this year, the Florida Supreme Court, in Tracey v. State of Florida, held that real time cell site location information is protected by the Fourth Amendment.

However, in May of this year, in United States v. Davis, the Eleventh Circuit Court of Appeals reversed an earlier three judge panel upon rehearing en banc, and held there is no reasonable expectation of privacy in these cell phone location records and, even if there were such an expectation, a warrantless search would still be reasonable. 785 F.3d 498.

On July 31, Davis’ lawyers petitioned the U.S. Supreme Court to review and overturn the Eleventh Circuit’s decision in Davis v. United States. If the Court accepts the case, perhaps the Court will resolve the issue of whether the warrant requirement of the Fourth Amendment applies to searches of  CSLI.