The International Atomic Energy Agency (IAEA) is the UN‑related body that oversees international cooperation, standards and verification in the peaceful use of nuclear energy and nuclear materials. In UK and Irish legal practice it is most often encountered in nuclear regulation, export control, environmental law, sanctions, defence and public international law.The term is used descriptively but its role and functions are reflected in international instruments and in domestic legislation, including nuclear safeguards, safety and security regimes in the UK and Ireland. The IAEA conducts inspections and monitoring under safeguards agreements, issues binding and non‑binding standards, and provides the framework for verifying that nuclear material is not diverted to weapons.For England & Wales, Scotland and Northern Ireland, the IAEA underpins obligations implemented through the Office for Nuclear Regulation, safeguards law and certain foreign affairs and security legislation. In Ireland, it informs regulatory oversight of radiological protection, nuclear safety and international commitments. Across all four jurisdictions, references to the IAEA in statutes, regulations, treaties and licences are generally consistent, signposting obligations on states and operators to comply with IAEA safeguards, reporting and safety standards.