This chapter outlines the principles and practical applications of Trauma-Informed Justice (TIJ), an approach that recognises the prevalence and impact of trauma in justice-involved populations. Drawing on models from health and social care, it details the 4 R’s of TIJ—Realise, Recognise, Respond and Resist re-traumatisation—and illustrates how they can be embedded in justice systems through training, screening, intervention and evaluation. The chapter evaluates the evidence base for TIJ, noting both its benefits and the gaps that remain. It concludes that TIJ is not a soft option, but a pragmatic and evidence informed framework that promotes safety, rehabilitation and long-term reductions in reoffending.