Credibility in an Age of Algorithms

Abstract

Evidence law has a “credibility” problem. Artificial intelligence creators will soon be marketing tools for assessing credibility in the courtroom. While credibility is a vital concept in the United States legal system, there is deep ambiguity within the law about its function. American jurisprudence assumes that impeachment evidence tells us about a witness’s propensity for truthfulness. Yet this same jurisprudence focuses fact-finders on a distinct inquiry: whether a witness has the status or outward appearance of a person who is worthy of belief. In the face of this equivocation about what credibility in the legal system is or should be, the terms of engagement will be set by the creators of algorithms in accordance with their interests.

This Article illuminates the actual and purported function of credibility in the law through analogies to two existing algorithmic products. One is the U.S. financial credit score. The other is China’s experiment with a “social credit” scoring system. These analogies show that a predictive approach to credibility is structurally distinct from a worthiness-centered one. They also deepen critiques of both approaches as they appear in current practice and as we contemplate the credibility of the future.