[4CJ]

Secession was a public act, not just a marriage, and Congress has the opportunity to guide how it's proven according to Article IV.

Two points - secession is not a public act - it is a sovereign act of the people of the state. Public acts are those done by state legislatures and/or other state officials ["the suit concerns the public acts of an officer of the State government", Osborn v. Bank Of United States, 9 Wheat. 738 (22 US) (1824); "the public acts of public officers purporting to be exercised in an official capacity and by public authority", United States v. Arredondo, 6 Pet. 691 (31 US) (1832)]

The Effects Clause states, "[a]nd the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof."

Not "must", but may. Congress has already enacted the applicable laws.

[#3Fan]

A sovereign act of the people of a state is a public act. The Secession Commissions were put together by the legislatures anyway. And the states agreed to have Congress guide the process of proof so they must give them that opportunity and secession is not a marriage and so would require laws to guide it.