By Emily Berman. Full text here.
According to both courts and commentators, the Fourth Amendment regulates the government’s collection of data, but not its use. That is to say, once data is lawfully in the government’s possession, the Constitution places no limits on how it is employed. I argue that we should reject this conventional wisdom and instead recognize a role for the Fourth Amendment in regulating the government’s use of information, irrespective of how it was collected. The need for this radical shift in Fourth Amendment doctrine becomes plain once one recognizes that contemporary methods of post-collection use of information can—and often do—implicate privacy in ways equally as problematic as those raised by collection alone. The most troubling of these are uses that implicate what has been labeled “the aggregation problem”: aggregation and analysis of data collected from disparate sources allows the government to extract revelations that cannot be gleaned from viewing that data in isolation. I argue those database queries that implicate the aggregation problem should be considered searches and regulated by the Fourth Amendment. At the very least, whenever a query of aggregated data about a particular U.S. person returns knowledge, of which direct collection would qualify as a search, the query itself should be considered a search. And while such an expansion of Fourth Amendment doctrine is no small undertaking, the Foreign Intelligence Surveillance Court’s oversight of government surveillance programs already provides a blueprint for how to design and implement such a regime.