Short answers, pulled from the story.
Northpointe released the COMPAS software system in 1998 to help U.S. courts decide how to treat defendants before trial. The company later changed its name to Equivant while the tool remained a staple in states like Wisconsin and California.
The software calculates risk scores based on specific behavioral factors including current charges, prior arrest history, residential stability, employment status, community ties, and substance abuse issues. It uses three distinct scales to measure pretrial release, general recidivism, and violent recidivism through data points like age-at-intake and vocational education problems.
In July 2016, the Wisconsin Supreme Court issued a ruling regarding the use of COMPAS risk scores during sentencing proceedings. The court decided judges could consider these scores but must provide warnings about the tool's limitations and cautions due to concerns over proprietary algorithms violating due process rights.
A 2016 investigation by Julia Angwin at ProPublica found stark racial disparities where blacks were almost twice as likely as whites to be labeled higher risk without actually re-offending. Conversely, white defendants were much more likely than black defendants to be labeled lower risk yet go on to commit other crimes.
Studies comparing COMPAS accuracy against human judgment revealed mixed results with the software achieving an accuracy rate of 65 percent while untrained individuals reached 63 percent individually or 67 percent collectively. Later research from Williams College in 2024 showed that while use of COMPAS reduced confinement rates overall, it exacerbated differences between racial groups in Broward County.