Final answer:
Judicial review is the power of the courts to determine the constitutionality of actions by Congress, the president, and the states, thus serving as a fundamental check on the other branches of government as per the established checks and balances system.
Step-by-step explanation:
Judicial review is the power of the courts to assess whether the actions of Congress, the president, and state governments align with the U.S. Constitution. Established by the Supreme Court case Marbury v. Madison in 1803, judicial review serves as a check on legislative and executive powers, ensuring that no law or executive action can violate the constitutional framework.
This review process forms a core component of the checks and balances system, designed to balance the powers of the three branches of government. Although judicial review is not explicitly mentioned in the Constitution, the Supreme Court granted itself this authority, signifying its critical role in the American legal system. When a law or action is deemed unconstitutional, it is rendered null and void.
The power of judicial review extends beyond the Supreme Court to lower federal courts and even state courts. Judges must justify their decisions in writing, subject to scrutiny by other legal professionals and the public, which creates internal limitations. Furthermore, external checks exist, such as the ability of Congress to modify the court structure and the president's power to appoint judges. These external and internal mechanisms ensure judicial accountability and help maintain a balanced federal structure.