GPS data about an alleged drug dealer’s location obtained from a GPS device attached to his car without a warrant, violated the defendant’s Fourth Amendment guarantee of privacy. In US v. Jones the US Supreme Court ruled 9-0 that prosecutors could not use the ill-gotten GPS data. However the Court, in its opinion, included a broader reference to GPS data from wireless devices:
... cell phones and other wireless devices now permit wireless carriers to track and record the location of users—and as of June 2011, it has been reported, there were more than 322 million wireless devices in use in the United States.
So even though the Court ruled against using location data obtained without a warrant in a criminal case, it also effectively acknowledged that wireless GPS data may be the next area of privacy concern.
However when parties voluntarily provide information to Internet sites, their expectation of privacy is different. As Justice Sotomayor stated:
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 for one doubt that people would accept without complaint the warrantless disclosure to the Government of a list of every Web site they had visited in the last week, or month, or year.
So the Supreme Court likely has more to say about privacy protection as it relates to GPS and Internet data.