What principle allows the Supreme Court to declare a law unconstitutional?

The principle that allows the Supreme Court to declare a law unconstitutional is known as Judicial Review. This foundational concept empowers the judiciary, particularly the Supreme Court, to evaluate laws and executive actions against the Constitution. If a law is found to violate constitutional principles, the Court has the authority to invalidate it.

Judicial Review is significant because it reinforces the rule of law and ensures that legislation aligns with the Constitution, which is the highest law of the land. This mechanism was established in the landmark case of Marbury v. Madison in 1803, where Chief Justice John Marshall articulated the power of the Court to review and nullify laws that conflict with constitutional provisions. This principle acts as a critical check on legislative and executive actions, safeguarding individual rights and maintaining the integrity of the Constitution.

Other options, while related to governance, serve different functions. Checks and Balances refers to the system designed to prevent any one branch of government from becoming too powerful, but it does not specifically address the judiciary's role in evaluating laws. Separation of Powers outlines the distinct roles of the legislative, executive, and judicial branches but does not directly grant the courts the authority to determine constitutionality. Federalism addresses the division of power between national and state governments but does not pert