The justice system describes the institutions, processes and laws through which the state prevents, investigates, prosecutes, adjudicates and enforces legal rights and obligations. It is a descriptive term, not usually defined in legislation or case law, but widely used in criminal justice, civil justice and public law contexts across England and Wales, Scotland, Northern Ireland and Ireland. In practice, the justice system encompasses: the police and investigative bodies; public prosecution services; criminal, civil, family and administrative courts and tribunals; the judiciary and juries; legal aid and legal representation; prisons, probation and youth justice; and regulatory and oversight bodies (for example, inspectorates, ombuds and human rights institutions). Usage and underlying concepts are broadly consistent across the four jurisdictions, but the structures are distinct: each has its own court hierarchy, prosecution service, legal aid framework and penal institutions, and Ireland operates within a separate constitutional and EU law framework. For legal practitioners, “justice system” is often used when addressing access to justice, systemic delay, court reform, judicial independence, rule of law compliance, human rights standards and the effectiveness of remedies and enforcement.