Abstract Effective coordination between prosecutors and police is essential for ensuring both investigative quality and procedural legitimacy. In 2021, China established a new institutional mechanism called the Investigation Supervision and Collaboration (ISC) Office to enhance prosecutor–police interaction by stationing prosecutors within police departments. This study examines whether these joint offices successfully strengthen prosecutorial oversight of police investigations. Drawing on surveys of 127 police officers and 48 prosecutors, 10 stakeholder interviews, and analysis of national and local regulations, we find that ISC offices represent a meaningful departure from earlier prosecutor-only liaison arrangements by incorporating police participation and emphasizing bidirectional collaboration. While official supervision metrics improved following the reform, practical challenges, including heavy caseloads and police resistance to external oversight, constrain effectiveness. In some regions, ISC offices have expanded into case-handling functions that risk blurring the constitutional boundary between investigation and prosecution. Although our findings derive primarily from developed eastern provinces and may not fully generalize to all regions, they reveal structural tensions in China’s ongoing efforts to balance prosecutorial control with police autonomy, offering insights relevant to comparative discussions on optimizing prosecutor–police relations in criminal justice systems worldwide.
Fang et al. (Thu,) studied this question.