The Trump administration may well be contemplating military action against Iran. Not only has it named Iran’s Islamic Revolutionary Guard a foreign terrorist group – the first such designation under the aegis of a nation-state – but Secretary of State Mike Pompeo suggested in recent Senate testimony that he has “no doubt there is a connection” between Iran and Al Qaeda.
Pompeo’s effort to connect Iran and Al Qaeda relates to the legal means by which the president may order the use of military force. Under the U.S. Constitution, Congress has the authority to determine whether the nation should go to war—and the president has the authority, as commander-in-chief, to prosecute a war that Congress has declared. This division of authority makes sense: Congress, and particularly the House of Representatives, is the department of the federal government closest to the people, and its members are most likely to be sensitive to the voices of the constituents or their family members who will be involved in fighting on behalf of the nation.
It has been some time, though, since Congress formally declared a war in the way contemplated by the constitutional text. Since World War II, Congress is more likely to authorize the use of military force rather than prepare a declaration of war. Which is why the secretary of state seeks to link Iran and Al Qaeda: should such a connection exist, the President could take military action against Iran pursuant to the Authorization to Use Military Force (the “AUMF”).
Issued by Congress in the wake of the September 11 attacks, the AUMF authorized President George W. Bush to use all “necessary and appropriate force” against those who “planned, authorized, committed or aided” the September 11 attacks, as well as associated forces and persons who provided refuge to our enemies. Congress has never withdrawn or modified the AUMF and, because it gives such broad discretion to the executive to engage in military action that shares a plausible connection to September 11, no president since Bush has seemed in a particular hurry to see Congress retire or rewrite the law. Indeed, every president since September 11 has relied on the AUMF as a source of authority to engage in a wide range of military actions.
The reason is simple. Presidents who believe military action is warranted essentially have a choice: seek congressional approval for that action, or try and shoehorn the proposed action into the AUMF. This is not a difficult choice for the current administration: given the hostility of the Democratically-controlled House to almost any Trump proposal, it seems unlikely the president could secure congressional approval of any military action against Iran absent an evidentiary showing that neither Pompeo nor any other senior administration official seems prepared to make. Indeed, despite the administration’s pleas, Congress recently voted to end military support to Saudi Arabia for its war in Yemen.
If the AUMF did not exist, the president would have to go to Congress and plead his case. He would have the burden to justify the appropriateness of military action, and he and his representatives would have to convince a majority of Congress to approve such action. Regardless of the outcome, that kind of interplay between the executive and legislative departments, representing overlapping constituencies in different ways and bringing different perspectives to bear on the issue whether to engage the nation militarily, would more closely resemble the separation of powers arrangement the framers likely had in mind when they assigned Congress the power to declare war and the President the power to wage it.
This is not to say there is a constitutional problem with the AUMF, or with presidential reliance upon it. Rather, the problem is that the continued availability of the AUMF in its original form weakens Congress’s ability to perform its constitutionally assigned function when it comes to the most fateful decisions the people’s representatives can make. Given the potential consequences of military engagement – to the men and women in uniform and the nation itself – it is difficult to believe the framers would have preferred the President act alone when initiating armed conflict.