Does ‘Big Data’ Threaten Due Process?

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Illustration by Christoph Scholz via Flickr

It was the largest gang bust, to that point, in New York City history.

On June 4, 2014, 103 suspected members of rival gangs who had turned their upper Manhattan neighborhood into a “war zone” were charged with a string of violent crimes, including two homicides.

But what really set it apart from previous anti-gang sweeps conducted by the office of Manhattan District Attorney Cy Vance was the method used to gather the information that led to the arrests.

Four years earlier, the Manhattan DA was the first prosecutor in the country to launch what was called a Crime Strategies Unit (CSU), which combined data picked up from surveillance technologies, social network analysis and digital tracking with traditional detective work to locate and identify individuals believed responsible for violent crime in their neighborhoods.

Since then, DAs around the country have followed suit with similar “intelligence-driven” prosecution systems that exploit the vast and growing databases that record the activities of millions of Americans—from license-plate scanners, facial recognition technology and cellphone tracking devices to street-corner video cameras and shot-spotters—to fight crime in ways that were unimaginable to 20th century law enforcement.

Critics have warned the use of so-called “Big Data” technologies that can collect terabytes of unstructured information about an individual without his knowledge represent a potential threat to privacy; but there’s another issue that is only just becoming apparent.

The “evidence” produced by these increasingly sophisticated surveillance tools can also undermine one of the key protections available to defendants in U.S. courtrooms: the right to see any information before trial that might prove their innocence.

“While prosecutors’ offices, like the rest of the professional world, are beginning to embrace a data-driven future, these systems have not been engineered to identify exculpatory or impeaching evidence for the defense,” wrote Andrew Guthrie Ferguson, a professor at the University of District Columbia David A. Clarke School of Law.

In a forthcoming paper for the UCLA Law Review, Ferguson warned that the inability to identify such “exculpatory” evidence—the requirement for which has been codified in Supreme Court rulings beginning with the 1963 Brady v. Maryland decision—represents a “design gap [that] threatens the legitimacy of the criminal justice system.”

Ferguson cites the 2014 Manhattan gang bust as an example how the new technology’s ability to help prosecutors focus proactively on criminal patterns and associations can also disrupt the traditional mechanism that have been in place over the past decades to ensure that the constitutional requirement of “due process” is followed.

Using the new technological tools, investigators can search for patterns, connections and insights that were never available to them before; but the current “search” technology is programmed to automatically discard or ignore data that is regarded as irrelevant to proving guilt.

That, warns Ferguson, means information which might once have been part of traditional investigations and would normally be handed over to defense attorneys before trial—doubts about eyewitness testimony, allegations that put a suspect far from the scene of a crime for which he is charged—are now lost in cyberspace.

Ultimately, Ferguson wrote in his paper, entitled “Big Data Prosecutions & Brady,” the inability to isolate “material evidence” that might prove a defendant’s innocence could undermine most of the crime-fighting advantages of “intelligence-driven” prosecutions.

“Building a digital investigation system that collects but cannot identify material evidence not only jeopardizes criminal cases, but the legitimacy of the criminal justice system,” Ferguson argued. “A prosecutor should not be in court unable to identify a process whereby she can find potential Brady material in their investigatory system.”

Ferguson says a solution is available by borrowing a model used by intelligence services.

As more DAs eagerly adopt the system and turn their offices into virtual “intelligence” offices, they should incorporate how intelligence agencies around the world classify the wide variety of unofficial information they pick up, according to Ferguson.

Intelligence reports from operatives in the field usually employ some coding system that grades the reliability of the information they obtain and the dependability of the informant, as well as any additional material that might cast doubts on their conclusions—all in the interests of giving policymakers as wide a basis as possible for drawing prudent conclusions.

It should not be hard for conscientious prosecutors to apply the same methods to fulfill their duties to provide Brady material to the defense.

“This duty would include more than simply looking at the facts about each of the players in a case (the traditional process), but how those players relate to each other and relate to the criminal justice system over time,” Ferguson wrote.

He added:

In a traditional system, an eyewitness might just be an eyewitness. In a big data system that eyewitness might be better thought of as the accumulated connections, statements, and relationships that can be found in the larger prosecution dataset.

 In a traditional system, an address might just be the location of a shooting. In a big data system, that address has a history which must be understood for possible motives, connections, and rivalries.

Ferguson acknowledged that applying a version of the same careful coding to evidence obtained through surveillance activity, social media information, video camera material not only requires more effort by investigators but adds to the volume of information.

But he pointed out that methods to develop search tools for Brady material should be well-within today’s technological capacities.

The alternative, Ferguson warns, is allowing technology to undermine the constitutional guarantees of a fair trial that ensure respect for our system of justice.

“While the volume, velocity, and variety of information may have changed, the law has not,” Ferguson wrote.

The full paper can be downloaded here.

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