Marbury v. Madison and the power to strike down laws
Judicial review is the power of courts to examine legislation and executive action, striking down those that violate the Constitution. This authority does not appear explicitly in the Constitution; it was established by Chief Justice John Marshall in Marbury v. Madison (1803), which held that when a law conflicts with the Constitution, courts must apply the Constitution as the supreme law. The case involved a minor appointment dispute but articulated the foundational principle that the Constitution binds judges and the judiciary must enforce it.
Marbury established three core propositions: the Constitution is law that courts must interpret, the judiciary must determine what the law is, and when laws conflict with the Constitution, the Constitution controls. This reasoning applies to state laws as well as federal statutes, giving federal courts authority to strike down both. Without judicial review, the Constitution would be whatever the legislature decided it meant, undermining the written limits on government power.
Checks and balances through constitutional enforcement
Judicial review is essential to the separation of powers. It prevents the executive and legislature from expanding beyond constitutional bounds. If Congress passes a law explicitly violating the First Amendment's free speech protections, courts strike it down. If the executive indefinitely detains citizens without trial, courts enforce the Fifth Amendment's due process protections. Without this power, constitutional constraints on government would be advisory only.
However, judicial review is exercised with restraint. Courts presume laws constitutional and invalidate them only when no reasonable interpretation makes them valid. Judges also respect legislative judgments on matters of policy and economics, applying deferential review standards like rational basis analysis. Political questions and matters of justiciability limit the scope: courts will not decide questions committed to other branches by the Constitution itself, such as treaty ratification or impeachment.