Separation of powers

A system of government that assigns legislative, executive, and judicial authority to distinct institutions. It limits concentrated power by giving each branch separate responsibilities and, often, ways to restrain the others.

Checks and balances: A system in which separate government branches can limit one another’s powers. It supplies the reciprocal restraints that make divided authority a limit on power.
Polybius: A Greek historian whose account of Rome described a mixed constitution balancing monarchic, aristocratic, and popular elements. His analysis of Rome supplied an early account of divided political authority.
Presidential system: A form of government with a separately elected executive serving independently of legislative confidence. It typically gives the executive and legislature distinct institutional mandates.
Fusion of powers: An arrangement in which executive and legislative authority are institutionally joined or closely integrated. It contrasts with systems that place those functions in separate institutions.
Legislature: A deliberative body with authority to make laws for a political community. It holds the lawmaking authority assigned to one branch.
John Locke: An English philosopher whose political writings argued for limited government and distinguished legislative from executive power. His distinction influenced later arguments for dividing governmental functions.
Parliamentary system: A form of government in which the executive depends on the confidence of the legislature. Its executive-legislative relationship differs from a strict institutional separation.
Mixed government: A constitutional arrangement combining elements associated with monarchy, aristocracy, and democracy. It balances social or political orders rather than dividing authority chiefly by governmental function.
Executive branch: The part of government that implements and administers laws and public policy. It exercises the governing and administrative authority separated from lawmaking and judging.
Montesquieu: A French political thinker whose Spirit of the Laws analyzed political liberty and the distribution of governmental powers. He gave the separation of legislative, executive, and judicial powers its influential formulation.

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