Which principle ensures that each branch of government has the authority to monitor and limit the powers of the others?

The principle that ensures each branch of government has the authority to monitor and limit the powers of the others is Checks and Balances. This system is fundamental to the structure of the United States government as outlined in the Constitution. It is designed to prevent any one branch—executive, legislative, or judicial—from becoming too powerful, thus safeguarding against tyranny and abuse of power.

Checks and Balances operate through various mechanisms whereby each branch can respond to and regulate the actions of the others. For instance, while the executive branch can veto legislation, the legislative branch can override that veto with a supermajority vote. Additionally, the judicial branch has the power to rule laws or executive actions unconstitutional, providing a check on both the legislative and executive branches.

Although the Separation of Powers also plays an important role by delineating distinct functions and responsibilities for each branch, it is the Checks and Balances that specifically focus on the oversight and limitation of powers among the branches. Federalism refers to the division of power between national and state governments, and Judicial Review is the ability of the courts to evaluate the constitutionality of legislative acts and executive actions, but neither embodies the comprehensive monitoring function that Checks and Balances does.