The legal answer is not going to help us.
From the piece:
The government’s war powers must be boundless, at least in theory. We must be able to marshal all our might to repel any conceivable existential threat. Yet the Constitution, the sole legitimate source of the government’s power to levy war, is, quintessentially, the citizen’s protection against aggression by that same government. Thus, the tension between government’s war powers and the citizen’s fundamental rights is a conundrum. It simply cannot be resolved with finality.
Neither side of our debate is satisfied with that. We want fixed rules. But fixed rules work only if they answer every conceivable hypothetical. So the debate lurches inexorably to worst-case scenarios.