Sanctity of contract describes the principle that freely negotiated contracts should be honoured and enforced according to their terms, with courts being slow to interfere or rewrite the parties’ bargain. It underpins contract law across England and Wales, Scotland, Northern Ireland and Ireland, and is reflected in judicial reluctance to imply terms or invoke public policy to defeat clear contractual wording.The expression is descriptive rather than a statutory term, but is recognised in case law as part of the broader respect for freedom of contract and commercial certainty. It informs judicial approaches to interpretation, remedies, frustration, illegality and the limitation of doctrines such as undue influence and economic duress.In commercial contracts, sanctity of contract supports enforceability of exclusion clauses, entire agreement clauses and agreed remedies, subject to statutory controls (for example, unfair terms, consumer protection and competition law). In all UK and Irish jurisdictions, courts balance sanctity of contract against fairness and public policy, but the core idea-that parties are held to their bargains where properly formed-remains consistent and central to transactional risk assessment and contractual drafting.