if the supreme court declares a law unconstitutional they are exercising what principle
judicial review
title: Federal government of the United States text: adjudicates "cases and controversies"—matters pertaining to the federal government, disputes between states, and interpretation of the United States Constitution, and, in general, can declare legislation or executive action made at any level of the government as unconstitutional, nullifying the law and creating precedent for future law and decisions. The United States Constitution does not specifically mention the power of judicial review (the power to declare a law unconstitutional). The power of judicial review was asserted by Chief Justice Marshall in the landmark Supreme Court Case "Marbury v. Madison" (1803). There have been instances in the past where such declarations have title: Nullification (U.S. Constitution) text: seeking to declare the federal law unconstitutional. Such a lawsuit is decided by the courts, with the Supreme Court having final jurisdiction. This is the accepted method of challenging the constitutionality of a federal statute. This is not nullification, even if the courts uphold the state's position and declare the federal statute unconstitutional. The theory of nullification is that the states have the unilateral power to determine the constitutionality of federal laws, and that a state's determination of unconstitutionality cannot be reviewed or reversed by the courts. Thus, nullification involves a declaration by a state that a federal statute is title: Constitutionality text: Constitutionality Constitutionality is the condition of acting in accordance with an applicable constitution; the status of a law, a procedure, or an act's accordance with the laws or guidelines set forth in the applicable constitution. When one of these (laws, procedures, or acts) directly violates the constitution, it is unconstitutional. All the rest are considered constitutional until challenged and declared otherwise. An act (or "statute") enacted as law either by a national legislature or by the legislature of a subordinate level of government (such as a state or province) may be declared unconstitutional. However, governments do not just create laws. title: Supreme Special Court text: concerning the constitutionality of a law is introduced into the "Supreme Special Court" (after the issuing of contradictory decisions of the Supreme Courts), the Court has the constitutional right to declare an unconstitutional legal provision as "powerless". This means that the unconstitutional legal provision still exists (it is not formally "null and void"), but it is expelled from the Greek "law and order". The decision of the "Supreme Special Court", declaring the unconstitutionality of a legal provision is final, irrevocable, binding for every Greek court, including the Supreme Courts, and judges the matter once for ever. No court has the title: Judicial review in the United States text: the United States, unconstitutionality is the "only" ground for a federal court to strike down a federal statute. Justice Washington, speaking for the Marshall Court, put it this way in an 1829 case: If a state statute conflicts with a valid federal statute, then courts may strike down the state statute as an unstatutable violation of the Supremacy Clause. But a federal court may not strike down a statute absent a violation of federal law or of the federal Constitution. Moreover, a suspicion or possibility of unconstitutionality is not enough for American courts to strike down a statute. Alexander Hamilton