Four MacArthur grantees have created the Observatorio Ciudadano del Sistema de Justicia (OCSJ) – the Citizen Observatory of the Justice System – to strengthen Mexico’s criminal justice system through monitoring, analysis, advocacy, and case dissemination. The 2008 Constitutional Reform to the Mexican criminal justice system was the first attempt in 90 years to integrate greater controls for transparency and rights protection in the system. Civil society welcomed the reform, but asserts there is a need for greater monitoring of its implementation. Toward that end, OCSJ, formed by Asistencia Legal por los Derechos Humanos, Comisión Mexicana de Defensa y Promoción de Derechos Humanos, Instituto de Justicia Procesal Penal, and Instituto Mexicano de Derechos Humanos y Democracia, will begin its work in Mexico City and seven other states where inadequate implementation of the 2008 reform has been documented. The group hopes to reform certain practices, including the use of pretrial detention, and will share their analyses publicly.