information:extraction
Supreme Court interpretations

However, in the case of California v. ARC America Corp., 490 U.S. 93 (1989), the Supreme Court held that if Congress expressly intended to act in an area, this would trigger the enforcement of the Supremacy Clause, and hence nullify the state action. The Supreme Court further found in Crosby v. National Foreign Trade Council, 530 U.S. 363 (2000), that even when a state law is not in direct conflict with a federal law, the state law could still be found unconstitutional under the Supremacy Clause if the "state law is an obstacle to the accomplishment and execution of Congress's full purposes and objectives". Congress need not expressly assert any preemption over state laws either, because Congress may implicitly assume this preemption under the Constitution. Finally, in Murphy v. National Collegiate Athletic Association the Supreme Court enforced the Supremacy Clause by overturning Federal law as an unconstitutional encroachment into the domain of the states not within of the limits of the Delegated powers, stating that " The Constitution confers on Congress not plenary legislative power but only certain enumerated powers ".