There's a state of war ~ ever since we were attacked!
That's not part of the problem. The USSC majority didn't care if there was a war or not, they simply extended their authority beyond that provided for by the Constitution.
Eventually we'll have to resolve this issue with the Court the way the citizens of Venice dealt with a wayward Doge.
BTW, it only happened once. All future Doges got the message.
Then why not make it official? You can always claim to be at war. Heck, we've had the "war on drugs" for decades now, but that doesn't give us the right to inter all drug abusers for the duration. When congress declares war, that makes it official and that's important. Then instead of being "detainees", our prisoners would be either POW's or saboteurs and we could legally keep them for the duration or execute them depending on their status.
If you're unwilling to officially declare a war, then you shouldn't be surprised when people don't take it seriously.