Is Secession Constitutional?

I think that it depends on the circumstance. For example if congress were to pass a law that was unjust then I think they have the right to secession, or if the president decided during war to use the US troops for himself then I think that they have a right to Secession. Another is if the constitutional is no longer followed. Otherwise I think they have no right to secession. I think that right now they have the right to secession because they past a law that is unconstitutional in my opinion.