Final answer:
The principle that divides government power among the executive, legislative, and judicial branches is called the Separation of Powers, designed to ensure a balanced system with checks and balances.
Step-by-step explanation:
The principle of government that divides power among the executive, legislative, and judicial branches is known as the Separation of Powers. This design is intended to provide a system of checks and balances, where each branch has distinct and independent powers and areas of responsibility, preventing any single branch from gaining too much power.
The legislative branch is responsible for making laws, the executive branch for implementing and executing laws, and the judicial branch for interpreting laws and upholding the constitution.
Thomas Jefferson, in his 1797 letter to James Madison, affirmed the spirit of the Constitution as the separation of these three functions. This concept has been a foundation of the American political system since the late 18th century.
Furthermore, the federal system adds to this by allocating governmental powers not only among the branches of government but also between national and subnational (state) levels, ensuring a further division of powers.