This study investigates the roles of trust in citizens and compliance with agency policies in mediating the direct and indirect relationships between internal procedural justice and external procedural justice among Chinese and Taiwanese police officers. Based on survey data collected from 1,253 police officers, this study comparatively analyzes whether supervisory treatment of officers is predictive of trust in citizens and willingness to follow agency policies, which in turn is linked to their willingness to act fairly and justly toward citizens on the street. The results indicate that officer trust in citizens mediates the relationship between internal and external procedural justice in both China and Taiwan, but compliance with agency policies does not. Internal procedural justice directly predicts external procedural justice among Taiwanese officers, but such a connection is not found among Chinese officers. Implications for future research and policy are discussed.