Look at the California Workers Compensation System -

Field pre-emption may be understood as a species of conflict pre-emption: A state law that falls within a pre-empted field conflicts with Congress' intent (either express or plainly implied) to exclude state regulation."].)

Constitutional Principle.

The supremacy of the federal government is expressed in Article VI of the federal Constitution: "This Constitution and the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the constitution or laws of any state to the contrary notwithstanding." (See 16 Am.Jur.2d, Constitutional Law 70 et seq., 288 et seq.)

"The relative importance to the State of its own law is not material when there is a conflict with a valid federal law. . . . [A]ny state law, however clearly within a State's acknowledged power, which interferes with or is contrary to federal law, must yield." (Free v. Bland (1962) 369 U.S. 663, 82 S.Ct. 1089, 1092, 8 L.Ed.2d 180, 183.) Read the Carrillo vs. ACF case

https://scholar.google.com/scholar_case?case=12995148712985490823&q

Summarize the Pre-emption rules, and the legal principles discussed and resolved in this case.