The Supreme Court ruled on Friday that a warrant is generally required for police to obtain historical records of a person's cell-site records.
The decision providing protections for the data collected each time a person's cellphone connects to a cellphone tower — data that Chief Justice John Roberts wrote provides "a comprehensive chronicle of the user’s past movements" — is a victory for privacy advocates.
Roberts wrote the court's 5–4 decision, holding that the acquisition of such records is a Fourth Amendment search and that police generally must show probable cause to obtain such records.
"[T]his case is not about 'using a phone' or a person’s movement at a particular time," he wrote. "It is about a detailed chronicle of a person’s physical presence compiled every day, every moment, over several years."
Roberts was joined in his decision by the court's four more liberal justices. His four more conservative colleagues dissented — each writing their own opinion as to why, in their view, the court's decision was incorrect.
In the case before the court, police had obtained 127 days of cell-site records for Timothy Carpenter, who was suspected of being part of a series of robberies in Michigan and Ohio. Those records, Roberts noted, provided "12,898 location points cataloging Carpenter's movements — an average of 101 data points every day." They also provided a basis for his conviction — being used at trial and cited in the prosecution's closing arguments.
Police could not have obtained such information in the past without much difficulty, Roberts noted, holding that the records represent a new type of "tireless and absolute surveillance." People have a reasonable expectation of privacy — the touchstone for Fourth Amendment protections — in those records, the court held, because they detail "the whole of [their] physical movements."
The government argued that the records could be obtained without a warrant under the "third-party doctrine" — in which the court has held that, for example, bank records and information about what numbers a person calls, records regularly maintained by companies, can be collected without a warrant because they are freely provided to businesses.
Although the government maintained that the case presented a "straightforward application" of that rule, Roberts wrote for the court that applying that doctrine to cell-site records would be "a significant extension of it to a distinct category of information."
Instead, the court's majority focused more on a pair of cases in which the court has found that evolving technology has changed the analysis of the issue. "When confronting new concerns wrought by digital technology," Roberts wrote, "this Court has been careful not to uncritically extend existing precedents."
Justice Anthony Kennedy, dissenting from the court's decision, was joined by Justices Clarence Thomas and Samuel Alito. He echoed the government's position, writing, "Adherence to this Court’s longstanding precedents and analytic framework would have been the proper and prudent way to resolve this case."
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