Constitutional clauses are specific provisions within a written or unwritten constitution, or constitution‑like instruments, that allocate and limit powers of state institutions and protect fundamental rights. In UK and Irish legal practice, the term is descriptive rather than a defined statutory concept, and is used by judges, academics and practitioners when analysing constitutional texts and principles.In Ireland, “constitutional clauses” commonly refers to particular Articles of Bunreacht na hÉireann (for example, provisions on separation of powers, fundamental rights, or amendment procedures), frequently cited in constitutional litigation, judicial review and public law advisory work.In the UK (England & Wales, Scotland and Northern Ireland), the expression is used more flexibly. It may refer to: clauses in statutes with constitutional character (such as the Scotland Act 1998 or Human Rights Act 1998); entrenched or quasi‑entrenched provisions; or sections reflecting constitutional principles developed through case law, including those discussed in leading public law decisions.Across all four jurisdictions, constitutional clauses are central to questions of legislative competence, judicial review, devolution, human rights protection and the relationship between domestic law and international or EU‑derived obligations.