The Constitution of the United States defines a government with three branches: executive, legislative and judicial. Each branch has certain powers, but those powers are also bound by specific limits, exercised primarily in a system of checks and balances by the other branches. This concept is known as "separation of powers," according to an overview on the website of the National Conference of State Legislatures, a term coined by Charles-Louis de Secondat, an 18th-century French social and political philosopher. The legislative branch makes laws, but they must be signed by the executive to take effect, or they may be vetoed. The judicial branch rules on the laws' constitutionality. Legislators can respond by overriding a veto, changing a law or amending the Constitution.…