the idea of dividing the government into three branches
Separation of powers The separation of powers, often imprecisely and metonymically used interchangeably with the trias politica principle, is a model for the governance of a state. Under this model, a state's government is divided into branches, each with separate and independent powers and areas of responsibility so that the powers of one branch are not in conflict with the powers associated with the other branches. The typical division is into three branches: a legislature, an executive, and a judiciary, which is the trias politica model. It can be contrasted with the fusion of powers in some parliamentary systems where the executive and legislature are unified.
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.