Assessing randomness in case assignment: the case study of the Brazilian Supreme Court

TL;DR

This paper evaluates the randomness of case assignment in the Brazilian Supreme Court using statistical models, highlighting issues with secrecy and proposing guidelines for transparent, secure, and auditable procedures.

Contribution

It introduces a statistical model to assess randomness in judicial case assignment and applies it to the Brazilian Supreme Court's opaque algorithm.

Findings

The assignment process shows deviations from true randomness.

The closed-source algorithm lacks transparency and auditability.

Guidelines for improving random judicial procedures are proposed.

Abstract

Sortition, i.e., random appointment for public duty, has been employed by societies throughout the years, especially for duties related to the judicial system, as a firewall designated to prevent illegitimate interference between parties in a legal case and agents of the legal system. In judicial systems of modern western countries, random procedures are mainly employed to select the jury, the court and/or the judge in charge of judging a legal case, so that they have a significant role in the course of a case. Therefore, these random procedures must comply with some principles, as statistical soundness; complete auditability; open-source programming; and procedural, cryptographical and computational security. Nevertheless, some of these principles are neglected by some random procedures in judicial systems, that are, in some cases, performed in secrecy and are not auditable by the involved parts. The assignment of cases in the Brazilian Supreme Court (Supremo Tribunal Federal) is an example of such procedures, for it is performed by a closed-source algorithm, unknown to the public and to the parts involved in the judicial cases, that allegedly assign the cases randomly to the justice chairs based on their caseload. In this context, this article presents a review of how sortition has been employed historically by societies, and discusses how Mathematical Statistics may be applied to random procedures of the judicial system, as it has been applied for almost a century on clinical trials, for example. Based on this discussion, a statistical model for assessing randomness in case assignment is proposed and applied to the Brazilian Supreme Court in order to shed light on how this assignment process is performed by the closed-source algorithm. Guidelines for random procedures are outlined and topics for further researches presented.