The Supreme Court has effectively “future-proofed” the Fourth Amendment against threats to privacy posed by the expansion of data surveillance technology, according to a leading commentator on Internet law.
Andrew Guthrie Ferguson, a professor at the University of the District of Columbia’s David A. Clarke School of Law, called the court’s majority ruling this month in Carpenter v. United States a landmark decision that “signals a new openness to ensure that the Fourth Amendment protects the digital lives of citizens.”
The narrow 5-4 decision requires police to obtain a probable cause warrant in most cases to access cellphone data. The defendant in the case, Timothy Carpenter, said police had violated his constitutional protections against unreasonable searches and seizures when they obtained records of his movements through cell-site location data held by his private cellphone company.
Writing in his blog for the Harvard Law Review, Ferguson said the Court’s decision recognized that a cellphone provider’s automatic retention of cell-site location information (CSLI) merited the same kind of privacy protection traditionally granted to an individual’s private papers and communications.
The ruling effectively “began the process of future-proofing the Fourth Amendment” against “encroaching big data politicking technologies,” Ferguson wrote.
“In an age of growing big data surveillance technologies capable of monitoring individuals and groups across entire cities, this systems update to the Fourth Amendment is a significant marker of the Court’s future intent,” he added.
Ferguson noted that the decision sets an important precedent for other legal tests likely on authorities’ use of digital technology, such as facial-recognition software and “smart-car” data, in their investigations.
But he also pointed out that the dissenting opinions in the case, which turned on “analog” interpretations of the Constitution that appeared to exclude information held by a third party, also opened the way for a debate about what constitutes a “reasonable expectation of privacy.”
Ferguson noted that the newest Justice, Neil Gorsuch, suggested that the traditional use of the third-party doctrine to define the kind of “property” that police and courts can obtain through subpoena powers needs to be reexamined.
The Carpenter ruling declares that courts will be required to ask whether individuals have a reasonable expectation of privacy for personal data held outside their control.
At the same time, the ruling has left “more than a few loose ends for lawyers and law professors to puzzle through in the coming years,” wrote Ferguson.
“But, given a path to choose between the past and the future, the Supreme Court chose to bring the Fourth Amendment into the digital future and protect against growing technologically enhanced police surveillance powers.”
The full version of Ferguson’s blog can be downloaded here.