Katia Savchuk

When the underlying data they rely on is incomplete—and it often is—the growing use of machine learning tools in America's criminal justice system can have devastating effects.

Patrick Ball has advised nine truth commissions, four U.N. missions, and dozens of advocacy groups in more than 30 countries. And his non-profit, the Human Rights Data Analysis Group, "represents, without a doubt, the world's top people doing statistical work on human rights violations."