There is a huge and interesting argument on whether it was legal for the States which became the Confederacy to leave the Union. I can see interesting points in both sides of this argument. I come down on the side saying it was legal for the Southern States to secede, even if it might have been a bad idea.
One thing I don't see addressed by people arguing that States could not secede is the issue of West Virginia. Prior to the Civil War West Virginia did not exist as a separate entity, it was simply a part of the State of Virginia. After the Civil War began, West Virginia broke away from Virginia and was a new state in the Union. Someone will correct me if I am wrong on this description.
My question is, IF West Virginia could leave Virginia, Why couldn't the various Confederate States leave the Federal Union ???