The legal term peace, sometimes king's peace (Latin pax regis) or queen's peace, is the common-law concept of the maintenance of public order.

The concept of the king's peace originated in Anglo-Saxon law, where it initially applied the special protections accorded to the households of the English kings and their retainers. A breach of the king's peace, which could be either a crime or a tort, was a serious matter. The concept of the king's peace expanded in the 10th and 11th centuries to accord the king's protection to particular times (such as holidays), places (such as highways and churches), and individuals (such as legates). By the time of the Norman Conquest, the notion of the king's peace became more general, referring to the safeguarding of public order more broadly. In subsequent centuries, those responsible for enforcing the king's peace (besides the king himself) included the King's Bench and various local officials, including the sheriff, coroner, justice of the peace, and constable.

In modern Britain, the police services are responsible for keeping the peace, a duty distinct from their duty of law enforcement. The concept has remained relevant in English law; in R v Secretary of State for the Home Department, ex parte Northumbria Police Authority (1989), the Court of Appeal for England and Wales held that the government could exercise prerogative powers to maintain the peace of the realm.