The attack on Iran violates (or will soon violate) three legal prohibitions:

(1) The declare war clause of the U.S. Constitution, which gives Congress, not the President, the authority to declare war. Throughout Democrat and Republican administrations, lawyers have preserved significant room for a president to use military force abroad at a level below what constitutes “war” under the Constitution, requiring congressional authorization. The executive branch’s legal standard, up until now at least, was set out in a 2011 opinion of Caroline Krass of the Office of Legal Counsel in DOJ. justice.gov/sites/defau…. This attack, which aims to remove the Iranian regime through massive airstrikes, which has already resulted in U.S. casualties, and where the president predicts more U.S. deaths to come, is inarguably “war” under the standard set out in the Krass opinion.

(2) The 60-day limitation on the use of force without congressional authorization in the War Powers Resolution. The War Powers resolution’s 60-day clock would apply even if the attack on Iran fell below the level of force that constituters “war” under the Krass opinion. The operative term in the WPR is “hostilities.” The Krass opinion also sets out the standard for whether the use of force rises to the level of “hostilities” that trigger the 60-day limit. Here, since the use of force amounts to war under the Constitution, it vastly exceeds the standard that triggers the WPR.

(3) The UN Charter. Many commentators criticize the use of force as violating “international law,” in that the UN Charter outlaws war without UN Security Council approval, except in cases of imminent self defense. The attack on Iran clearly violates that prohibition. But it is important to remember that the UN Charter is not just international law, it is the law of the land. It is a treaty. And the president took an oath to “take care” the faithful execution of the laws of the United States.