Self-defence - the 'ancient right' - has never been more relevant than in the present era of widespread calls for criminal justice reform. The book substantially advances the patinaed discussion by introducing for the first time a comprehensive value-centric approach to thinking about the defence's deeper rationale. It tackles core issues such as the relative importance of the State's claimed monopoly on force, procedural justice and the need to shore up the justice system's legitimacy and creditworthiness, everyone's presumptive 'right to life,' and the importance of ensuring equal standing between citizens. And, in so doing, the book breaks ground by addressing public perceptions of 'just' and 'right' outcomes, as well as the emphasis legal systems place (and should place) on State power.