PNAS published an RCT of Procedural Justice training for police, to foster fair/respectful treatment of citizens. Quick take: High-quality RCT found no effect on community perception of police legitimacy (primary outcome) but suggestive effects on some other outcomes.

Program and Study Design:

• The study randomly assigned 28 police officers in 3 cities (Tucson, Cambridge, Houston) to Procedural Justice training vs control, and randomly assigned 120 crime hot spots in the cities to be policed by trained vs control officers over a 9-month period. Procedural Justice training was an intensive, 5-day course.

Findings:

• The study found no significant effect on the study's primary pre-specified outcome - residents' perception of policy legitimacy (e.g., trust in police, obligation to obey police), as measured with community surveys.

  
  

• The study found positive effects on some secondary outcomes (e.g., residents' perceptions of police misbehavior such as harassment, observer measures of police behavior during ride-alongs) but not others (e.g., citizen calls for service - the main pre-specified measure of crime).

  
  

• The positive effects are encouraging but I think best viewed as preliminary because: (i) study measured many outcomes (which can cause false-positives), and (ii) T officers might temporarily display expected PJ behaviors for observers during ride-alongs (social desirability bias).

  
  

• Also, the 28 police officers in the sample had all volunteered for the study, so we don't yet know the effect of Procedural Justice training on other police who don't volunteer.

Comment:

• Given the urgency of police reform, we need more high-quality RCTs like this to identify effective police training programs.

• Disclosure: My former employer, Arnold Ventures, funded this study.