Separation of powers is a political doctrine under which the legislative, executive and judicial branches of government are kept distinct, to prevent abuse of power. This US form of separation of powers is widely known as "checks and balances."
The principle of separation of powers traces its origins at least as far back as Aristotle's time. During the Age of Enlightenment, several philosophers, such as John Locke and James Harrington, 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 charge, however, that the framers misinterpreted Montesquieu. According to Isaac Rice (a nineteenth century political scientist), Montesquieu opposed concentrating power in a single person, rather than a single source. It was Montesquieu himself who developed the idea of establishing a form of separation of power in government. The United States borrowed some of the philosophies of Montesquieu to create the system of checks and balances that is present in the United States government today. Rice therefore suggested that a parliamentary system—e799bee5baa6e997aee7ad94e58685e5aeb931333234303636which would not comply with the strict doctrine of separation of powers—would nevertheless be consistent with Montesquieu's philosophy.
Strict separation of powers did not operate in Britain, a country whose political structure served in most instances as a model for the government created by the US Constitution. In the UK, the King-in-Parliament (the King acting with the consent of the House of Lords and House of Commons) was the supreme lawmaking authority. The executive branch acted in the name of the King - it was known as "His Majesty's Government" - as did the judiciary. The King's Ministers were in most cases members of one of the two Houses of Parliament, and the Government needed to sustain a majority in the House of Commons. One minister, the Lord Chancellor, was at the same time the sole judge in the Court of Chancery and the presiding officer in the House of Lords. Thus, one may conclude that the three branches of British government often violated the strict principle of separation of powers, even though there were many occasions when the different branches of the government disagreed with each other.
Some US 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 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."
