This chapter introduces the framework of responsive legality, identifying its main twenty-first-century features as distinct from previous twentieth-century administrative justice models. It outlines that responsive legality is alive when public officials value flexible, adaptive engagement with the needs of applicants, strive to balance procedural and substantive justice, draw on the cognitive techniques of applying experience and verifying the truth and demonstrate a dual valuation of the rule of law and orientation towards an ethic of care. The chapter solidifies what is broadly different between twentieth- and twenty-first-century administrative justice, distilled in the responsive legality framework, to lay the foundation for detailed examination in subsequent chapters.