In the age of smart phones, information that is automatically collected by cell phone towers has the potential to reveal an enormous amount of personal information about our whereabouts, including the types of doctors we see, how often we attend church, and whose houses we sleep in at night. 

In 2015 the ACLU led a coalition of public interest groups in filing a friend-of-the-court brief in the Sixth Circuit, arguing that such information should not be available to law enforcement unless it is obtained through a search warrant signed by a judge.  In 2016 the Sixth Circuit issued a split decision rejecting our argument, holding that the government did not conduct a “search” for Fourth Amendment purposes when it obtained cell phone location information from wireless carriers, and therefore did not need a warrant.  We then assumed direct representation of the defendant and asked the U.S. Supreme Court to take the case

In June 2018, the Supreme Court reversed, holding for the first time that citizens have a reasonable expectation of privacy in the data that tracks their cell phone location over time. This pathbreaking decision will finally help usher the Fourth Amendment into the 21st century.

(Carpenter v. United States; ACLU of Michigan Attorneys Dan Korobkin and Michael J. Steinberg; National ACLU Attorneys Nathan Freed Wessler, Ben Wizner, Brett Kaufman, Cecillia Wang, Jennifer Granick, and David Cole; co-counsel Harold Gurewitz.)

Read more case background here.

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