Answer:
he U.S. Constitution achieved limited government through a separation of powers: "horizontal" separation of powers distributed power among branches of government (the legislature, the executive, and the judiciary, each of which provide a check on the powers of the other); "vertical" separation of powers (federalism) ...The Principles Underlying the Constitution
Federalism aside, three key principles are the crux of the Constitution: separation of powers, checks and balances, and bicameralism.