In the case Carpenter v. United States, the ACLU is defending Timothy Carpenter, who was arrested in 2011 and convicted of committing a robbery in Detroit. Police in the investigation were able to obtain months' worth of location data from cell phone companies on the suspects in the case without a warrant. This is a normal occurrence in the course of a police investigation. Carpenter was able to appeal his case, but the appellate court ruled that the Fourth Amendment doesn't protect this kind of data and no warrant was required. Now the case will be heard by the Supreme Court.

Tech companies have a specific interest in making sure this kind of personal data is protected by the Constitution (the Fourth Amendment protects citizens from unreasonable searches and seizures without probable cause) because their companies rely on user trust. Their customers must trust them to keep this kind of confidential information private. Given "people's participation in today's digital world," the old, rigid rules "should yield to a more nuanced understanding of reasonable expectations of privacy," according to the brief.

This is an important case when it comes to the extent of our privacy rights in the digital age. We entrust all kinds of personal data to third-party providers and social networks; "the government needs a good reason to get its hand on it," as ACLU attorney Nathan Freed Wessler said. These laws and precedents haven't yet caught up to the current digital age, and it's important that they do when the Supreme Court hears this case in the fall.