This week, in United States v. Jones, all the justices of the Supreme Court agreed that the U.S. Constitution precludes the government from monitoring our movements using installed GPS technology absent a warrant supported by probable cause.
But the justices did not agree on the reasoning underlying this decision. The majority, in an opinion written by Justice Antonin Scalia, viewed the vehicle to which the government had surreptitiously attached the GPS device as an “effect.” Accordingly, the use of the device constituted a search within the literal meaning of the Fourth Amendment—that is, it constituted a physical occupation of property by the government for the purpose of obtaining information, which the Fourth Amendment prohibits absent a warrant.
Notably, the majority declined to apply the analysis developed in Katz v. United States to determine whether a constitutional search had occurred. Under the Katz test, a court will inquire whether the government invaded a defendant’s objectively reasonable expectation of privacy. Scalia explained that it was unnecessary to apply the Katz test here, for that test does not preclude “previously recognized protection for property.” In other words, because this case involved an actual physical invasion of property, there was no need to determine whether the defendant had any objectively reasonable expectation of privacy.
Writing for himself and three of his colleagues, Justice Samuel Alito reached the same result applying Katz. The concurring justices concluded that “the use of long term GPS monitoring in investigations of most offenses impinges on expectations of privacy,” and by any measure the monitoring in this case—four weeks—could only be considered long-term. Scalia and Alito argued back and forth about whether the Katz test has supplanted property-based determinations of privacy, but it seems clear that Katz will control when, unlike this case, the government’s monitoring does not involve an actual physical invasion of property.
Justice Sonia Sotomayor joined the majority but issued a concurrence that may prove the most interesting—and prescient—of all the opinions in Jones. She agreed that, at a minimum, “[w]hen the Government physically invades personal property to gather information, a search occurs,” regardless whether the defendant has an objectively reasonable expectation of privacy. And she warned against the dangers posed by the ability of the government, via GPS technology, “to assemble data that reveal private aspects of identity,” an ability that could “alter the relationship between citizen and government in a way that is inimical to democratic society.” She urged the courts to take account of these aspects of GPS technology “when considering the existence of a reasonable expectation of privacy in the sum of one’s public movements.”
More importantly, Justice Sotomayor suggested that, in light of the ubiquity of GPS and other similar technologies, perhaps the time has come “to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties.” Every day we reveal information about ourselves to others that is captured and stored—to our friends, to our family members, to our banks, to on-line service providers like Amazon and Facebook. Simply because we choose to disclose this information in the context of relationships of trust does not mean that the government should automatically have access to it. In the digital age, as Justice Sotomayor put it, Fourth Amendment doctrine should not “treat secrecy as a prerequisite for privacy.”