ACLU: Absent warrant standard, police could monitor anyone via location data

Lawyers representing a man convicted of six robberies in the Detroit area have now filed their opening brief at the Supreme Court in one of the most important digital privacy cases in recent years. This case, Carpenter v. United States, asks a simple question: is it OK for police to seize and search 127 days of cell-site location information (CSLI) without a warrant? Previously, lower courts have said that such practices are compatible with current law. But the fact that the Supreme Court agreed to hear the case suggests that at least four justices feel that perhaps the law should be changed.

In Carpenter, as is the case in countless modern criminal cases, law enforcement was able to obtain the relevant records directly from the mobile phone provider with a court order that has less stringent requirements than a warrant. This is not a trivial distinction. A so-called "d-order" can be circumspect with how information is obtained by authorities. It does not, as the Fourth Amendment demands, require as much particularity. A warrant, unlike a d-order application, also mandates a signed and sworn affidavit ("on oath or affirmation"), as the Constitution requires, which describes the "places to be searched and the things to be seized." Carpenter's attorneys, many of whom are from the American Civil Liberties Union, argue in their filing that the current legal standard gives the government too much leeway. "If the Court were to accept this argument, the government could use this tool to monitor the minute-by-minute whereabouts of anyone—from ordinary citizens to prominent businesspersons to leaders of social movements," they wrote in their August 7 brief.