I agree, California has not made a valid case. I will not discuss the legitimacy of secession.
Actually, in my opinion the Feds have taken the legitimate action... California has been sued in
Federal Court. The issue being with the legitimacy of federal law, and the violation of said law
by a State. The State courts have no jurisdiction.
I quote the US. Constition, Article 6, clause II
"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."