States acceded to the Federal Constitution they can secede from. http://books.google.com/books?id=q_M9AAAAIAAJ&dq=albert+taylor+bledsoe+davis+a+traitor&printsec=frontcover&source=bl&ots=vWxmgmzQ0h&sig=oVKoEHBf5sVdduijWjfIa_hOFoU&hl=en&ei=PPGVSuivI-qI8QaVvoS3DA&sa=X&oi=book_result&ct=result&resnum=1#v=onepage&q=&f=false
Opinion.