The Supremacy Clause simply states that, in the event there is a conflict between state and federal law federal law will prevail.
Partially correct.
With respect to federal laws, then, the Supremacy Clause gives "supreme" status only to those that are "made in Pursuance" of "[t]his Constitution." Ibid.; see
3 J. Story, Commentaries on the Constitution of the United States §1831, p. 694 (1833
This structural limitation may be implicated in a pre-emption case if the federal law at issue is beyond the scope of Congress'
enumerated powers. Expansion of congressional power through an "increasingly generous ... interpretation of the commerce power of Congress," for example, creates "a real risk that Congress will gradually erase the diffusion of power between State and Nation on which the Framers based their faith in the efficiency and vitality of our Republic." Garcia v. San Antonio Metropolitan Transit Authority, 469 U. S. 528, 583-584 (1985) (O'Connor, J., dissenting); see also Marbury v. Madison, 1 Cranch 137, 176 (1803) ("The powers of the legislature are defined, and limited; and that those limits may not be mistaken, or forgotten, the constitution is written").
.