Separation of powers under the United States Constitution
Separation of powers is a political doctrine originating in the writings of Charles de Secondat, Baron de Montesquieu in The Spirit of the Laws, in which he argued for a constitutional government with three separate branches, each of which would have defined abilities to check the powers of the others. This philosophy heavily influenced the writing of the United States Constitution, according to which the Legislative, Executive, and Judicial branches of the United States government are kept distinct in order to prevent abuse of power. This United States form of separation of powers is associated with a system of checks and balances.
This article needs additional citations for verification. (February 2015)
During the Age of Enlightenment, philosophers such as Montesquieu advocated the principle in their writings, whereas others, such as Thomas Hobbes, strongly opposed it. Montesquieu was one of the foremost supporters of separating the legislature, the executive, and the judiciary. His writings considerably influenced the opinions of the framers of the United States Constitution.
Some U.S. states did not observe a strict separation of powers in the 18th century. In New Jersey, the Governor also functioned as a member of the state's highest court and as the presiding officer of one house of the New Jersey Legislature. The President of Delaware was a member of the Court of Appeals; the presiding officers of the two houses of the state legislature also served in the executive department as Vice Presidents. In both Delaware and Pennsylvania, members of the executive council served at the same time as judges. On the other hand, many southern states explicitly required separation of powers. Maryland, Virginia, North Carolina and Georgia all kept the branches of government "separate and distinct."