Judicial Review is the power of courts to assess whether a law, policy, or executive action is in accordance with the Constitution. This process ensures that legislative and executive branches do not exceed their authority and that individual rights are protected. Through Judicial Review, courts can invalidate laws or actions that are found unconstitutional. This principle was established in the landmark case of Marbury v. Madison in 1803, which set the precedent for the judiciary's role in interpreting the law and maintaining the balance of power among government branches.