Which principle involves the division of government into three separate branches?

The principle that involves the division of government into three separate branches is known as Separation of Powers. This concept was famously articulated by political philosopher Montesquieu and is a foundational element in the U.S. Constitution. It establishes the framework for the federal government by dividing it into the legislative, executive, and judicial branches. Each branch has distinct powers and responsibilities, which helps prevent any one branch from becoming too powerful.

This division is crucial as it promotes a system where each branch can operate independently while also maintaining a level of accountability to the others. It ensures that authority is not concentrated in a single entity, thereby protecting individual liberties and against tyranny.

Checks and Balances, while closely related to Separation of Powers, specifically refers to the mechanisms that allow each branch to monitor and limit the powers of the others, ensuring that all branches work together effectively without overstepping their bounds. Judicial Review pertains to the courts' ability to invalidate laws if they are found to be unconstitutional, and Federalism refers to the distribution of power between the national and state governments.