Conflict of interest describes a situation where a lawyer, fiduciary, director, trustee or public decision‑maker’s duty to a client or principal is, or may reasonably appear to be, compromised by their own interests or by duties owed to another. It covers actual, potential and apparent conflicts.In legal services, conflicts are governed by professional conduct rules rather than a single statute. The SRA Codes (England and Wales), Law Society of Scotland Practice Rules, Bar Standards Board rules, and the Law Societies of Northern Ireland and Ireland prohibit acting in a client conflict or an own‑interest conflict, subject to narrow exceptions (typically informed consent and effective information barriers). Practitioners must identify conflicts early, manage confidentiality and disclosure duties, obtain consent where permitted, and decline or cease to act if risks cannot be mitigated.In corporate and charity law, fiduciary duties and Companies Act 2006 ss 175–177 (UK) and Companies Act 2014 (Ireland) require directors to avoid conflicts and declare interests; charity trustees are subject to comparable duties.In public law and procurement, conflict rules address bias: the test for apparent bias (Porter v Magill) and ethics regimes require disclosure and recusal. Principles are broadly consistent across the UK and Ireland.