The New Jersey Supreme Court [official website] ruled [opinion, PDF] Thursday that police must obtain search warrants before obtaining tracking information from cell phone providers. The unanimous ruling marks the first time a state supreme court has recognized a Fourth Amendment [Cornell LII backgrounder] protection for cell phone location data. In the decision, Chief Justice Stuart Rabner noted that cellphone tracking technology has the potential to violate a person's privacy rights and must be subject to judicial review. Rabner also noted that no warrants will be required in emergency situations.
Courts and lawmakers remain divided on what types of warrants are required to perform cell phone searches. Earlier this month the Maine Legislature [official website] voted in favor [JURIST report] of a new law requiring police to obtain a warrant to track a cell phone. In May the Florida Supreme Court [official website] ruled [opinion, PDF] that police need a warrant [JURIST report] to search a defendant's cell phone at the time of arrest. In 2012 the US Court of Appeals for the Seventh Circuit [official website] ruled [opinion, PDF] that a warrantless search [JURIST report] of a suspect's cell phone to collect its phone number does not constitute a violation of Fourth Amendment protections against unreasonable search and seizure.