Pacta sunt servanda
Foundational contract-law principle that valid agreements are binding and must generally be performed in good faith.
Pacta sunt servanda expresses the binding force of contracts. In Swiss private law, parties who validly conclude an agreement are generally expected to perform it according to its terms and in good faith. The principle supports legal certainty and commercial reliability, but it is not absolute. Mandatory law, defects in consent, impossibility, illegality, abuse of rights, or exceptional doctrines such as changed circumstances may limit enforcement. The maxim is also central in public international law, with a distinct but related meaning.