The U.S. Supreme Court observed in "DaimlerChrysler Corp. v. Cuno" (2006): "No principle is more fundamental to the judiciary’s proper role in our system of government than the constitutional limitation of federal-court jurisdiction to actual cases or controversies.” The case-or-controversy requirement of Article III of the constitution requires plaintiffs to establish their standing to sue. Article III standing law is built on separation-of-powers principles. Its purpose is to prevent the judicial process from being used to usurp the powers of the legislative and executive branch of the U.S. federal government. Article III standing requires an injury that is “concrete, particularized and actual or imminent; fairly traceable to the challenged action and redressable by a favorable ruling.”