The decision of the Court in United States v. Jones was accompanied by two concurring opinions, one written by Justice Alito, and the other by Justice Sotomayor. The unanimous decision and ruling found that the government violated the Fourth Amendment's prohibition of unreasonable searches and seizures because a tracking device had been attached to the defendant's car without first obtaining a warrant. The placing of the device constituted a trespass, akin to breaking into someone's home or filing cabinet.
Justice Alito's well-reasoned concurrence went further, arguing that the notion of physical trespass as a predicate to finding a warrant necessary was outdated, and that beginning with the wiretapping cases of the 1960s, courts began to recognize that a more appropriate standard was whether or not a person had "a reasonable expectation of privacy" in a given situation. This approach, argued Alito, was far more effective in dealing with privacy issues in the digital era—as opposed to limiting the Fourth Amendment to the law of trespass, which essentially dates back to 1215.
Justice Sotomayor's opinion spoke to the world as we know it, and she couldn't have been more spot on. She wrote: "… it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties… This approach is ill-suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks. 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."
Justice Sotomayor separates the notion of intrusion from that of physical trespass while simultaneously untangling the often-confused ideas of privacy and secrecy. Why should anyone expect that the information that a customer has to provide to their bank will be made available to the Government without a Court-issued warrant? Absent that warrant, anything you intend to keep private should be kept private. Justice Sotomayor cited the decision in the 1967 case of Katz v. United States "[W]hat [a person] seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected."