Final answer:
The constitutional principle described by James Madison is Separation of powers.
Step-by-step explanation:
The constitutional principle described by James Madison is Separation of powers.
Madison is referring to Montesquieu's idea that the legislative and executive powers should be separated in order to preserve liberty. This principle is reflected in the U.S. Constitution, where power is divided among three branches of government: the legislative, executive, and judicial.
By having separate branches with distinct powers, no one branch can become too powerful, ensuring a system of checks and balances.