A night-watchman state, also referred to as a minimal state or minarchy, whose proponents are known as minarchists, is a model of a state that is limited and minimal, whose functions depend on libertarian theory. Right-libertarians support it only as an enforcer of the non-aggression principle by providing citizens with the military, the police, and courts, thereby protecting them from aggression, theft, breach of contract, fraud, and enforcing property laws.
In the United States, this form of government is mainly associated with libertarian and objectivist political philosophy. In other countries, minarchism is also advocated by some non-anarchist libertarian socialists and other left-libertarians. A night-watchman state has also been popularized by Robert Nozick in Anarchy, State, and Utopia (1974). The United Kingdom in the 19th century has been described by historian Charles Townshend as a standard-bearer for this form of government.