In his concurring opinion, Justice Jackson said the following:
“We should not use this occasion to circumscribe, much less to contract, the lawful role of the President as Commander in Chief. I should indulge the widest latitude of interpretation to sustain his exclusive function to command the instruments of national force, at least when turned against the outside world for the security of our society. But, when it is turned inward, not because of rebellion but because of a lawful economic struggle between industry and labor, it should have no such indulgence.”
There are a couple of ways to think about this passage in connection with the current case before the Court. One is that the Administration is claiming that Chicago is in rebellion and thus should receive deference. That said, if all the President must do to get the “widest indulgence of interpretation” for the domestic use of military force is to claim that a rebellion is ongoing, that’s not much of a limit.
Another thought is that Justice Jackson was talking about the President’s Article II authority. It’s a different story when statutory authority is being invoked. But that begs the question of whether there is statutory authority here; a subject on which I have no expertise.
A third thought is that maybe the President should not get interim relief in a situation when he is attempting to use military force domestically. In other words, “no such indulgence” should equal “no interim relief.” This would not be a comment on the merits.