The term "trias politica" or "separation of powers" was coined by Charles-Louis de Secondat, baron de La Brède et de Montesquieu, an 18th century French social and political philosopher. His publication, "Spirit of the Laws," is considered one of the great works in the history of political theory and jurisprudence. It inspired the Declaration of the Rights of Man and the Constitution of the United States. Under his model, the political authority of the state is divided into legislative, executive and judicial powers. He asserted that, to most effectively promote liberty, these three powers must be separate and acting independently.
Separation of powers, therefore, refers to the division of government responsibilities into distinct branches to limit any one branch from exercising the core functions of another. The intent is to prevent the concentration of power and provide for checks and balances.