The supremacy clause is normally misunderstood. Most people think it means that Federal law always trumps state law, regarding the same legal issue in question.

This isn't true.

Federal law trumps state law only when the issue is something that both sets of statutes are pursuing, AND the issue is something that was explicitly delegated to the Feds by "We the People."

For the Feds to be able to trump state authority, the Feds have to be exercising a legitimately bestowed constitutionally authority.

A new Federal health-care law mandating that one must buy a plan or go to jail...this does not fall within the realm of a legit Federal authority. The states can object.