The US Supreme Court [official website] on Wednesday heard oral arguments in Carpenter v. United States [docket], a case concerning law enforcement officers’ authority to collect an individual’s cell phone records to track his movements over an extended period of time.

This case arose from petitioner Timothy Carpenter’s conviction for armed robbery, for which he was sentenced [SCOTUSblog report] to 116 days in prison. At trial, the prosecution offered evidence of Carpenter’s location during the 127 days surrounding the robberies through cell phone records, which law enforcement obtained without a warrant or consent. Carpenter appealed to the Sixth Circuit and then to the Supreme Court, arguing the officers violated his Fourth Amendment expectation of privacy.

The question [JURIST report] the court is faced with in this case is: “[w]hether the warrantless seizure and search of historical cell phone records revealing the location and movements of a cell phone user over the course of 127 days is permitted by the Fourth Amendment.”

During arguments [text, PDF], Carpenter argued such a search is unreasonable due to the nature of cell phone record production and the span of time the records were obtained for. In comparing cell phone records to bank statements (which law enforcement may also obtain) Carpenter argues that less expectation of privacy is associated with bank statements, than cell phone records:

the information in bank records can be quite sensitive, but what it cannot do is chart a minute-by-minute account of a person’s locations and movements and associations over a long period regardless of what the person is doing at any given moment.

The government, on the other hand, argued cell phone records do not create a higher expectation of privacy and that their position is in line with the court’s precedent concerning the third party doctrine and collection of evidence without a warrant, stating: “[collecting cell phone records] is asking a business to provide information about the business’s own transactions with a customer.”

The justices’ comments seem to show more support for Carpenter, but if the court renders a decision in his favor, it will create a new, more defined precedent concerning the third-party doctrine and Fourth Amendment searches.