Why would it require court action before a secession vote?
Do you agree that the only 'justification' for the North attacking the South was the South attacked Federal forces on Ft Sumner first on 12 April 1861 at 4:30 am?
I find nothing in either The Declaration of independence or the US Constitution that would prohibit secession until after a court battle.
But I would like to hear your rational for court first.
My rationale for court first is that secession is the "nuclear option" and should be a last resort, not a first move.
If your goal is to have the south secede from the Union and are looking for any excuse to do so, then yes, by all means you could secede if Hillary unilaterally declared the Second Amendment null and void.
If, however, your goal (as is mine) is to preserve, protect, defend, and expand our God given Second Amendment rights, court would be your first option to have the unconstitutional actions of Hillary overturned, just as the courts overturned Obama's executive order on suspending deportations.