The Fourth Party Doctrine: Regulating Big Data With an Inference-Based Approach

Fourth Amendment law is inadequate to handle the privacy intrusions that are becoming part and parcel of the role Big Data plays in government investigations. The courts view data privacy ontologically through the lens of analog privacy intrusions—that is, they attempt to regulate government access to particular kinds of data, setting standards for what constitutes a search based on the nature of the data requisitioned. However, this approach leaves courts unable to regulate government’s use of state-of-the-art technologies which reveal individuals’ private lives by drawing inferences from one or more large datasets. These inferences are marketed to government officials, who use them (without a warrant) to gain deeper insights about individuals than those that are provided by the types of information currently protected by the Fourth Amendment. If the current regime persists, the courts could take decades to address inference-driven government investigation. By then, it will have rendered many of the Fourth Amendment’s protections moot.

In this Essay, I propose that courts reorient themselves to more effectively monitor Big Data-government collaborations by using: (1) an inference-facing principle to assess algorithmic privacy intrusions from a sounder technological and business perspective, and (2) a fourth party doctrine which applies the existing legal standard for the third party doctrine in Carpenter to regulate the government’s ability to deploy Big Data tools and the data science companies which manufacture them. This proposal promises to make Fourth Amendment enforcement adaptive and forward-facing and does not require the creation of new law. Instead, I draw upon fundamental privacy principles articulated by the Supreme Court in Carpenter to establish a framework for judges to apply and rapidly reshape American privacy law to comport with societal norms. Our proposal has implications for the civil sphere as well; it offers an avenue for privacy regulators to demarcate clear and reasonable rules of conduct for Big Data.