doo-doo-,doo-doo; doo-doo-, doo-doo. Welcome to the Twilight Zone.

“no authority has ever been given to the legislative branch, the executive branch or the judicial branch of the federal government to preempt state legislation.”

Here I go, actually reading the Constitution again. Article VI says:

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, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.

So who decides? Article III says:

The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish.

“Inferior” here means “subordinate,” but feel free to hold the other interpretation. Article III goes on to say:

The judicial Power shall extend to all Cases, in Law and Equity, arising under this Constitution, the Laws of the United States, and Treaties made, or which shall be made, under their Authority….

So there we are.
1. The Constitution trumps all state laws.
2. Judges must rule according to the Constitution.
3. The Supreme Court is in charge.
4. They are the authority in all cases relating to the Constitution.
So there’s your authority to pre-empt State legislation. Does it get much clearer?