Only it was legally in the hands of the union.
Though I agree ,whats legal or not at that point doesnt much matter anyways after they started shooting.
The South had no moral high ground to stand on from the begining and it only made matters worse by attacking.
The last time South Carolina tussled with the Federal Gov and threatened sucssession one of their own (Andy Jackson) came down in force with federal troops and they didnt start shooting.