Social Norms or Enforcement? A Natural Field Experiment to Improve Traffic and Parking Fine Compliance

Very little is known about the efficient collection of fines despite their indispensable contribution to local government budgets. This paper fills an important gap in literature by studying effectiveness deterrence (enforcement) and non-deterrence (social norms) letters that aim improve traffic parking fines. We discuss potential mechanisms through which these may affect fine compliance present results from a natural field experiment was implemented collaboration with Australian Capital Territory (ACT). find both increase payments significantly relative control group did not receive letter. The effect enforcement letter stronger than social norms Our analysis heterogenous treatment effects indicates addressing does change behavior young offenders, those who committed speeding offence, long outstanding debt above median. In contrast, generally effective across subgroups.