Regardless of his motivations, though, an active duty officer suing the Commander in Chief is, without a doubt, contrary to good order and discipline. Some might also argue that CPT Smith’s suit itself, not the war against ISIS, is fundamentally what goes against his oath. Too many times, people equate “I don’t like this” or “I think this is stupid” with “this is illegal” or “this is unconstitutional.”
I don’t know if the mission against ISIS is unconstitutional, but more importantly neither does CPT Smith. If he feels that strongly about it, he should resign his commission and pursue his lawsuit free from the bonds of military service and the Uniform Code of Military Justice. Suing the Commander in Chief while still a commissioned officer puts CPT Smith far more at odds with his oath than the actions of the President.