Legal Question in Civil Litigation in California

A complete answer requires far more space than provided here, and requires a detailed look at what "federalism" really means in the US. At a first cut, the Supremacy Clause does not apply to questions solely involving state law. A federal court's decision on a state law question (e.g., a question of how to interpret a California statute) is not binding on the state, because of the Supremacy Clause or anything else. The Supremacy Clause applies only to questions of federal law.

Mr. Perry is basically correct. More specifically, though, this is about "preemption." The Supremacy Clause only comes into play if the federal government intends to and has chosen to preempt state law on a particular issue or area of the law. Preemption can only be done by statute and the regulations issued under the federal statutes. Federal cases only come into play to the extent they interpret federal statutes that have preempted state law or if they contain a ruling on a question about whether a particular federal law preempts state law. Federal case law on a subject that is NOT preempted is only persuasive authority in state courts. So, for example, federal women and minority contracting preferences on federally funded airport construction are binding on SFO in spite of Prop 8 which prohibited preferences. As is the 9th Circuit case interpreting how those preferences are applied. But when a citizen if another state is sued in CA, and removes to federal court under diversity of citizenship and then disputes CA jurisdiction law, a federal court case interpreting CA jurisdiction law will be binding in that case but only persuasive authority in other cases.

The states have the ultimate authority on state law. Most law is state law. Federal courts are only binding on federal law. The supremacy clause only applies when a federal law (statute) conflicts with a state law. A federal court decision is not a federal statute.