Public law concerns the exercise of power by the state and public bodies, and the legal controls on government decision‑making and public administration. It typically governs relationships between individuals (or companies) and central government, devolved administrations, local authorities, regulators, the police and other public authorities. In the UK and Ireland, “public law” is a broad descriptive term rather than a single statutory definition. It encompasses constitutional law, administrative law (including judicial review), human rights, aspects of EU and retained EU law, and certain areas of criminal, immigration, asylum, mental health and prison law where state powers are engaged. Public law practice focuses on challenging or defending the legality, rationality and procedural fairness of decisions, policies and legislation, often by way of judicial review or statutory appeal. It is central to issues of separation of powers, the rule of law and access to justice. The concept and usage are broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland, though procedural rules, court structures and sources of constitutional law (for example, the uncodified UK constitution versus the written Irish Constitution) differ between jurisdictions.