Actually many of the British grants and deeds engendered court cases for years after independence. The same is true with lands taken or bought from Mexico.
Secession would only be legal with an amendment allowing it.
The Union was perpetual and not dissolved by the choice of one or more states. The constitution explicitly gives the fed gov the power to suppress Insurrection.
Meanwhile, her opponent wears no hat but is always black
But the British deeds were done away with. They held no future sway. Compensation may have been paid, but that was after the fact. Efforts to pay compensation to the Union for Fort Sumter and other facilities were made, but these were deliberately rebuffed by Lincoln. He didn't want to settle the matter peacefully. His backers in New York stood to lose enormous amounts of money if the South was allowed to establish it's own trade with Europe.
The Union was perpetual and not dissolved by the choice of one or more states.
So was the United Kingdom, but we found this thing called "natural law", and it convinced our founders that no one had the right to hold people in allegiance against their will, and so they wrote the Declaration of Independence which says it is a right of nature and of nature's God for people to have independence if they so wish.
The constitution explicitly gives the fed gov the power to suppress Insurrection.
It isn't an "insurrection" or a "rebellion" when states vote to leave the Union. It was called an insurrection" to unleash those powers, but that was a lie.
Chief Justice Samuel P Chase said that "secession is not rebellion" and he also cautioned Federal prosecutors not to bring Jefferson Davis to trial, because if they did, they would lose in the court room everything they had gained on the battlefield.
The trial would have exposed the lie that was used to unleash all that power on the South. The Federal prosecutors wisely chose not to pursue this idea further in Court.