It seems instinctive to us today to have government powers divided between an executive branch, a legislative branch, and a judicial branch. In the US, the three parts are well-defined in a system of checks and balances, whereas in a parliamentary system the executive seems to be an outgrowth of the legislature. But I think the distinct nature of the three types of power are still clearly identifiable.
When and where did this concept of three functions of government power get started? With the Magna Carta?
I once had a fascinating class in Early American history and we discussed this very subject. And if I recall correctly America’s 3-part government is based on the British model and Anglo-Saxon law. King to President is easy to see. As is House of Lords to Senate and House of Commons to House of Representatives. I can’t quite place the Judicial.
Perhaps it also goes back as far as Rome. Who were also quite proud of their 3 part system. I really should go dig up that paper for this but they had a Monarchy in the Emperor, a Oligarchy in the Senate and a Democracy in the people. And all were able to exert some power. I’ll see if I can find that paper.
While there may be superficial similarities between the British Parliament and American legeslative branches they are quite different in practice. The oversight function of the English senate is not a separation of power in the American sense as there are no distinct areas of responsibility. Parliamentary supremacy places all power within the legeslative branch. The English executive branch is almost indistinguishable from the legeslative.
I think you may be looking for Montesquieu’s concept of the balance of power in politics which had a distinct influence on the founders. The concentration of power in English government was felt to produce despotism which the founders sought to avoid.
Also keep in mind that there are two forms of separation of powers: The 3 part system and the federal state. It may be that the concept of federalism encouraged the development of further divisions.
It’s been a while since PolSci 101, but I believe that Montesquieu based his theories on the English model, by contrast to the French system of absolute monarchy under Louis XIV and XV. At the time he was writing, the British monarch still had some personal involvement in government, (what we now call responsible government had not yet evolved) so there was a clearer distinction between executive and legislative. There was also an independent judiciary, guaranteed by the Act of Settlement of 1701, though without an entrenched Bill of Rights.