Judicial activism is when courts do not confine themselves to reasonable interpretations of laws, but instead create law. Alternatively, judicial activism is when courts do not limit their ruling to the dispute before them, but instead establish a new rule to apply broadly to issues not presented in the specific action. "Judicial activism" is when judges substitute their own political opinions for the applicable law, or when judges act like a legislature (legislating from the bench) rather than like a traditional court. In so doing, the court takes for itself the powers of Congress rather than limiting itself to the powers traditionally given to the judiciary.
The Warren Court was prominent for engaging in judicial activism or, in a stronger version of the term, judicial supremacy. The judicial supremacy of the Warren Court claimed that segregation was not constitutional in the case Brown v. Board of Education and so therefore unilaterally destroyed an institution that was an integral part of society and widely supported in the areas where segregation was legal. The Warren Court imposed its political opinions, forcing schools to become desegregated. This action caused minorities in the United States, specifically African-Americans, to be legally equal with white Americans. This type of judicial supremacy is typical of liberal courts trying to give every person in the United States their rights and liberties guaranteed in the constitution. If the Warren Court had practiced Judicial Restraint, they would have seen that the U.S. constitution and its amendments do not specifically state any requirements regarding education, therefore, the supreme court has no official powers over the states' ability to regulate and maintain their respective educational services. African-Americans were not denied access to public education and so therefore the ruling by the Warren Court is judicial supremacy at its worst.