Assessing the causal mechanisms underlying procedural justice theory in the Netherlands

Increasingly, researchers are assessing the causal effects of procedurally just treatment by police on public attitudes using experimental vignettes across the world. However, there are two key limitations to this body of research, particularly when drawing causal conclusions about theoretical mechanisms. The first is that most research on procedural justice, and particularly using experimental vignettes, has been conducted in countries with similar roots in policing (i.e., Anglo-Saxon, English-speaking countries). The second limitation is that research on procedural justice theory using vignettes often fails to closely assess the mechanisms and potential confounds linking experiences of treatment and subsequent attitudes. The current study aims to address both of these gaps by replicating US experimental vignettes among a representative sample of Dutch residents. Specifically, we field a 3 × 2 × 2 between-subjects vignette to assess different components of procedurally just treatment by police on individual attitudes during a traffic stop. We assess causal assumptions using a series of follow-up questions about placebo characteristics, and investigate underlying mechanisms by analysing open-text responses following each police legitimacy item. The results from the current study show that, while procedurally just treatment by police was statistically related to perceptions of encounter-specific police legitimacy, the strength of the causal effect and underlying mechanisms were not so clear. Not only was a key causal assumption violated, indicating that the effect does not run only through the treatment, but respondents suggested that they would comply and trust police in the situation based on broader societal norms and expectations, not necessarily because of police behaviour. Methodologically, our study suggests that researchers using experimental vignettes need to pay more attention to causal assumptions. Theoretically, our study shows that those interested in testing procedural justice theory (and criminological theories more broadly) must think critically about identifying and evaluating competing mechanisms in different societal and institutional contexts.