In January 2012, the U.S. Supreme Court unanimously confirmed that Americans have constitutional protections against GPS surveillance by law enforcement, holding that GPS tracking is a "search" under the Fourth Amendment.
In United States v. Jones (at times known as United States v. Maynard), FBI agents planted a GPS device on a car while it was on private property and then used it to track the position of the automobile every ten seconds for a full month, all without securing a search warrant.
EFF and the Center for Democracy and Technology filed an amicus brief arguing that GPS tracking is fundamentally different from and more invasive than other surveillance technologies the court has allowed before, and that law enforcement use of GPS without a warrant violates Americans' reasonable expectations of privacy. The amicus brief was joined by Roger L. Easton, considered the father of GPS, and other technologists.
EFF was particularly gratified to see Justice Sotomayor, in concurrence, raising concerns about the failure of the Fourth Amendment caselaw to keep up with the realities of today's digital technologies. She said: "People disclose the phone numbers that they dial or text to their cellular providers, the URLS that they visit and the e-mail addresses with which they correspond to their Internet service providers, and the books, groceries and medications they purchase to online retailers . . . I would not assume that all information voluntarily disclosed to some member of the public for a limited purpose is, for that reason alone, disentitled to Fourth Amendment protection."