Isn't it clear that the Supreme Court cannot dictate to the President on matters central to the President's duty to fulfill his office? If the President violates the Constitution, the constitutional recourse is impeachment. A President who judges that a certain action is both constitutional, and essential to the maintenance of the republic, would be derelict in his formal duty if he deferred to the judicial branch and did not perform the action.
Let's be honest. The disagreement is not about the Constitutionality of Lincoln's actions, but about whether the Union was really at stake and whether it was a good thing that Lincoln preserved it. Those who say no, particularly to the second question, tend to say that Lincoln was assaulting the Constitution. Those who judge, with Lincoln, that the Union was in peril and that it was the president's sacred duty to preserve it, find little difficulty in seeing how his actions were Constitutional and necessary and wise. We should not let the matter be diverted into a proxy argument over Constitutional legality, when that matter clearly cannot be settled apart from the broader question of the nature of the federal union, and the president's duty to preserve it, and other related questions.
No doubt the union was in peril, but I can't find where the president's duties include preserving the union - is it written anywhere?
Here is the oath all Presidents (including Mr. Lincoln) must take before entering office:
''I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States.''
I see a duty to "preserve, protect, and defend the Constitution of the United States", but I see no duty to preserve the Union. Mr. Lincoln ignored the Constitution. He did things that were clearly unconstitutional. He violated his oath of office.
Saying he did it to preserve the union is not an acceptable excuse. What right did he have to make war on the southern states? Clearly the right to secession is enshrined in the Declaration of Independence. If the 13 Colonies had the right to seceed from England, then the Confederate States had the right to seceed from the United States.
Since the states had the right to seceed, the employment of force against them was, in and of itself, illegitimate. Certainly Lincoln cannot use an illegitimate war as a reason to ignore the Constitution.