The group must be headed by Captain Obvious, since Trump himself admitted it was not an emergency. (“I didn’t have to do this.”) Trump obviously lacks the moral and logical grounds for this action.
So what? You can’t shame Trump into action. The only weapon that works against him is the law, and all common sense notwithstanding, he may well have the authority to do what he did. I’m not a legal scholar, but it seems to me that the President has just about unlimited latitude to determine just what is a national emergency. The appropriate U.S. code doesn’t define an emergency, or place any constraints on what the President may call an emergency (nice law-writing there, boys).
The law does place one form of constraint on the President. Congress may say, “Sorry, no emergency exists,” but that resolution needs to come from both houses, and it needs Republican defectors to pass the Senate. Moreover, even if it passed the Senate, it can be vetoed, and neither chamber has the votes to override.
This will put the courts in a very difficult position when the declaration is challenged, since they are supposed to interpret laws, and there is really nothing there to interpret. Unless they choose to arrogate power to themselves, their only recourse seems to be to rule, “The law is clear that overriding the President’s judgment is the job of Congress, not of the courts.”
The other remaining question revolves around the proper definition of the President’s powers to move money around. Trump will argue that this law gives him the authority to tinker with the military construction budget. Irrespective of whether the courts support him on that one, I would normally argue that it is politically suicidal to screw the troops by taking money away from military housing for a border wall of debatable necessity. But the rules of normality don’t apply to Trump. He seems to be a genius at knowing how much crazy shit he can do without losing the support of his base.