This was decided in 1865, as I recall.
Yep.
We kill a bunch of them and take all their stuff.
This time, no one will go to war to force them to stay.
We might negotiate a divorce that give us the conservative areas, and maybe the Long Beach port.
Secession is not unconstitutional.
I'd say that what was decided was a state's unilateral decision to secede.
The author states:
"University of Virginia law school professor Cynthia Nicoletti told Business Insider, “There’s no legal path to secession.” Others point out that it would likely take a Constitutional Convention and ratification..."
I believe that there is a legal path that is far short of a proposing convention. It would be perfectly constitutional for Congress to pass a bill proposing an amendment to the Constitution that grants California's request to leave the Union. Then California would need 38 states to concur, and they're out.
I would not support Congress proposing a process of secession in a new amendment, as that would become an open door for all sorts of political havoc, with states feigning the secession process for simple legislative leverage. Instead, the precedent should be set that a state wishing to leave asks their delegation in Congress to propose an amendment requesting only that state's desire to leave, and then they lobby the remaining states in the union for concurrence.
-PJ