On November 29th, the U.S. Supreme Court will hear oral arguments in Carpenter v. US, a case essentially asking whether or not authorities need a warrant based on probable cause and signed by a judge to see your cellphone location data. For now, they do not. Given the fact that about 95% of Americans have cellphones, this case has major implications. Quartz reports:Mobile-service providers collect "cell site location information" (CSLI) for all phones, ostensibly to use for things like improving their networks. The U.S. government considers these data "routinely collected business records" rather than private information. That means it can demand the records without proving probable cause. That's what happened in the criminal case of Timothy Carpenter, accused of a series of Detroit, Michigan robberies. At Carpenter's trial, prosecutors presented evidence collected by private companies, obtained by the law without probable cause. They used 127 days-worth of cellphone-location data, amounting to almost 13,000 data points, to tell a circumstantial story of Carpenter comings and goings.
In its brief to the high court, filed in September, the justice department argued that when Carpenter signed onto his cell-phone provider's service, he agreed that his call records weren't private information belonging to him, but rather business records belonging to the company. Therefore, he should have "no reasonable expectation of privacy" when it comes to these records, government attorneys wrote. Carpenter argues that the location evidence was obtained illegally. The Sixth Circuit Court of Appeals denied that claim last year, basing their decision on Supreme Court cases from the 1970s: Smith v. Maryland and US v. Miller . The appeals court concluded that, under what's called the "third-party doctrine," Americans don't have a reasonable expectation of privacy in things like check deposit slips, similar banking records, and dialed telephone numbers.