Separation of powers is a political doctrine originating in the writings of Montesquieu in The Spirit of the Laws where he urged for a constitutional government with three separate branches of government. Each of the three branches would have defined abilities to check the powers of the other branches. This idea was called separation of powers. 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. 

During the Age of Enlightenment, philosophers such as John Locke 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.
Who agreed with such systems?
philosophers such as John Locke advocated the principle in their writings