And the Supreme Court law of latter times still says nothing about the interpretation of secession prior to the Civil War.
Actually it did, albeit in a rather unusual manner. Judge Anthony Scalia, who claimed to to interpret the law as the Founders had originally wrote it, had this to say about the subject of secession. It came in a reply to a letter by a screenwriter working on political farce that had Maine seceding from the US to join Canada sent to each of the Supreme Court Justices in 2006 on a lark;
"I’m a screenwriter in New York City, and am writing to see if you might be willing to assist me in a project that involves a unique constitutional issue.
My latest screenplay is a comedy about Maine seceding from the United States and joining Canada. There are parts of the story that deal with the legality of such an event and, of course, a big showdown in the Supreme Court is part of the story.
At the moment my story is a 12 page treatment. As an architect turned screenwriter, it is fair to say that I come up a bit short in the art of Supreme Court advocacy. If you could spare a few moments on a serious subject that is treated in a comedic way, I would greatly appreciate your thoughts. I’m sure you’ll find the story very entertaining."
Judge Scalia decided to actually reply to it and this is what he said;
"I am afraid I cannot be of much help with your problem, principally because I cannot imagine that such a question could ever reach the Supreme Court.
To begin with, the answer is clear. If there was any constitutional issue resolved by the Civil War, it is that there is no right to secede. (Hence, in the Pledge of Allegiance, “one Nation, indivisible.”) Secondly, I find it difficult to envision who the parties to this lawsuit might be. Is the State suing the United States for a declaratory judgment? But the United States cannot be sued without its consent, and it has not consented to this sort of suit.
I am sure that poetic license can overcome all that — but you do not need legal advice for that. Good luck with your screenplay."