How hard should it be for the police to get hold of reams of data showing every place you’ve been for months?

The Supreme Court will confront that question on Wednesday when it hears oral arguments in one of the biggest Fourth Amendment cases in years.

In 2013, Timothy Carpenter was convicted of being the ringleader behind a series of armed robberies of cellphone stores in and around Detroit, and was sentenced to almost 116 years in prison. His conviction was secured in part based on 127 days of location data that his cellphone service provider turned over to the police, showing that his phone had been in the vicinity of several of the robberies.

The police got those phone records without a warrant, which the Fourth Amendment generally requires, and which would have forced them to show they had probable cause to believe that Mr. Carpenter had committed a crime. Instead they relied on a federal law with a lower standard: “reasonable grounds to believe” that the records “are relevant and material to an ongoing criminal investigation.”