A night-watchman 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.
As a term, night-watchman state (Nachtwächterstaat) was coined by German socialist Ferdinand Lassalle in an 1862 speech in Berlin wherein he criticized the bourgeois-liberal limited government state, comparing it to a night-watchman whose sole duty was preventing theft, playing on the double meaning of the German term Nachtwächter to mean someone who was incompetent or stupid. The phrase quickly caught on as a description of capitalist government, even as liberalism began to mean a more involved state, or a state with a larger sphere of responsibility. Ludwig von Mises later opined that Lassalle tried to make limited government look ridiculous though it was no more ridiculous than governments that concerned themselves with "the preparation of sauerkraut, with the manufacture of trouser buttons, or with the publication of newspapers".
Proponents of the night-watchman state are minarchists, a portmanteau of minimum and -archy. Arche (ˈɑrki; ἀρχή) is a Greek word which came to mean "first place, power", "method of government", "empire, realm", "authorities" (in plural: ἀρχαί), or "command".