Which commission published the first national study of the U.S. criminal justice system?

The Wickersham Commission, officially known as the National Commission on Law Observance and Enforcement, was established by President Herbert Hoover in 1929. It is recognized for publishing the first comprehensive national study of the U.S. criminal justice system in 1931. The commission's findings addressed various aspects of law enforcement, including the effectiveness of police, the role of courts, and the impact of Prohibition on law enforcement practices.

This landmark study provided a foundation for future criminal justice research and reform by illustrating systemic issues within policing and the judicial process. It also laid the groundwork for subsequent commissions and studies that continued to evaluate and improve the American criminal justice system over the years.