There is a growing body of research on people’s perception of fairness in dealing with law enforcement and public institutions. This research has shown that people’s perception of the quality of police encounters depends less on outcomes, but more on whether they feel treated in a fair or procedurally just way.  Research has demonstrated that procedural justice is vital for building trust and increasing legitimacy in policing.  Open Policing has integrated these four pillars of procedural justice into our solution to measure, on a national scale, how policing in each community affects public trust.