The case centers on Timothy Carpenter who, in 2014, was convicted of multiple armed robberies and sentenced to 116 years in prison. The conviction came after the prosecution was granted access to Carpenter's cellphone location records -- data obtained through the Stored Communications Act and not with a warrant. On appeal, the Sixth Circuit upheld the ruling, drawing a line between the use of location records and messaging content, the latter of which wasn't used by the prosecution.
Law enforcement has been butting heads with mobile services a lot in recent years. They've gone up against companies like Facebook, Microsoft, Reddit and Twitter and have forced a rise in the use of encrypted messaging apps like Signal.
Carpenter's lawyers are arguing that obtaining his cellphone location records without a warrant is in violation of his Fourth Amendment rights, something the Justice Department denies. The case will be heard sometime during the Supreme Court's next term, which begins in October, and the decision could have major implications for how strongly privacy is protected in the justice system.