Enveloping the research evidence: How can policing deliver effective warning letters in a roads policing context?

Warning letters are used in response to various forms of traffic offending in the United States and are perhaps one of the most likely unsolicited encounters that a member of the public will have with policing. Despite this, there is a lack of research bringing together theoretical insight relevant to the development of letters as a form of public/policing interaction. This article draws on relevant theory and research to guide the practical design and delivery of letters. It considers how behaviour change, nudge theory, social norming approaches, the concepts of instrumental and normative compliance, and procedural justice can be used to guide the use of warning letters as a common outcome of roads policing-related encounters with the public. The article ends with a discussion of practical opportunities for applying the learning to the (re-)development of letters.