Which principle ensures that no branch of government can gain too much power?

The principle that ensures no branch of government can gain too much power is Checks and Balances. This framework is built into the Constitution to create a system where each branch of government—executive, legislative, and judicial—has specific powers and can oversee and limit the actions of the others. For example, while Congress has the power to make laws, the President can veto legislation, and the Supreme Court can rule laws unconstitutional. This interlocking system prevents any single branch from dominating the government, thus safeguarding against tyranny and ensuring accountability.

Other options touch on the distribution and function of government powers, but they don't specifically address the oversight and limits established among branches. Federalism describes the division of power between national and state governments, Separation of Powers delineates the distinct roles of each branch, and Judicial Review allows courts to interpret laws and their constitutionality but does not by itself create a balancing mechanism among branches.