In addition to its as-yet undetermined consequences for a potential US-Iran nuclear deal, “Operation Midnight Hammer”—the US military operation that involved aerial strikes on three key Iranian nuclear facilities in June—has brought a long-standing legal debate with considerable implications for US foreign policy to the fore: the scope of executive war powers under the US Constitution.
In the days following the strikes, Operation Midnight Hammer elicited considerable praise from lawmakers who favored direct US intervention in the Israel-Iran conflict. But a number of dissenting voices on both sides of the political aisle were quick to condemn the operation, arguing that President Trump exceeded his authority under the Constitution by attacking Iran without congressional authorization. Republican Representative Thomas Massey, for example, took President Trump to task during a Face the Nation interview, arguing that Iran posed “no imminent threat to the United States” at the time of the strikes. Democratic Representative Alexandria Ocasio-Cortez went a step further, asserting on social media that the president’s “disastrous decision” to strike Iran is “absolutely and clearly grounds for impeachment.”
In fact, the question of whether or not President Trump had legal authority to order strikes against Iran is more complex than either supporters or critics of the operation have let on.
War Powers Under the Constitution
In accordance with the separation of powers principle, the Constitution divides war powers between the executive and the legislative branches. Under Article I, Congress has the power to declare war, as well as various appropriations powers (‘powers of the purse’) that allow it to provide for the common defense and the maintenance of the armed forces. Under Article II, however, the president is named Commander in Chief of the army and the navy, and is thus empowered to direct the armed forces when called into service on behalf of the nation.
What this allocation of powers means in practice remains the subject of considerable debate. At a minimum, all agree that the president may order the armed forces to repel an attack against the homeland, regardless of whether or not he has congressional authorization to do so. This principle was affirmed by the Supreme Court in the Civil War-era Prize Cases (one of the few examples of case law in this area), where Justice Grier observed: “If a war be made by invasion of a foreign nation, the president is not only authorized but bound to resist force by force. He does not initiate the war, but is bound to accept the challenge without waiting for any special legislative authority.” It is also generally acknowledged that once the use of military force is authorized by Congress (whether through a formal declaration of war or statutory authorization), the president is in charge of operational, tactical, and other strategic considerations involved in the conduct of hostilities. In other words, while the Constitution gives Congress the power to ‘declare’ war, the power to ‘make’ war is reserved to the president.
A thornier question—and the one directly at issue in the context of Operation Midnight Hammer—is whether the president may, in his capacity as Commander in Chief, direct the armed forces to carry out limited military engagements in defense of US interests that arguably fall short of ‘war’ in the constitutional sense. The answer largely depends on the view of executive power one finds more convincing. That is, does a faithful interpretation of the Constitution require a narrow construction of the president’s Commander in Chief powers, or does the Constitution allow for a broader understanding of the powers at the president’s disposal?
In addition to the plain text of Article I, proponents of the narrow view typically point to the historical context of the debates over ratification of the Constitution. In 1787, the framers had only recently won their freedom after a bloody seven year war, and the example of the British monarch King George III, who enjoyed nearly unlimited war powers under the royal prerogative, loomed large in their minds as they took up the task of designing a constitutional framework for the young republic. As Justice Robert Jackson observed in the classic separation of powers case Youngstown Sheet & Tube Co. v. Sawyer: “The example of such unlimited executive power that must have most impressed the forefathers was the prerogative exercised by George III, and the description of its evils in the Declaration of Independence leads me to doubt that they were creating their new Executive in his image.”
Indeed, in The Federalist No. 69, Alexander Hamilton explained that while the president’s authority as Commander in Chief under the proposed constitutional framework would be “nominally the same with that of the King of Great Britain,” in substance it would be “much inferior to it,” as the powers of declaring war and financing the armed forces would now be granted to Congress. By breaking with the English model and entrusting these powers to the legislative branch, the framers intended to preclude a scenario where a single individual could draw the nation into a protracted war or conflict without first having consulted the people’s elected representatives. It follows for proponents of the narrow view that doubts about the scope of executive power in this area should be resolved in favor of Congress, which in theory at least would be less inclined than the executive to sacrifice the nation’s blood and treasure in costly foreign conflicts unless it was truly in the national interest.
While those who favor a broad view of executive power would surely concede that the president’s powers fall well short of an absolute monarch, they point out that the framers still recognized the need for a strong, energetic executive. In The Federalist No. 70, for example, Hamilton famously argued that good governance depended on a unitary executive capable of acting with “decision, activity, secrecy, and dispatch.” For proponents of the broad view, the virtues of executive power that Hamilton describes are doubly apparent in the context of contemporary international relations, which often involves precarious, fast-changing situations that demand decisive action.
More significantly, proponents of the broad view can point to numerous examples where the president has introduced US forces into hostilities without congressional authorization in the past, which they argue has effectively placed a “historical gloss” on the scope of executive war powers vis-a-vis Congress. Some prominent examples include the Korean War, the commitment of forces in Vietnam prior to the Gulf of Tonkin Resolution, the air campaigns in Bosnia and Kosovo during the 1990s, and the intervention in Libya during the Arab Spring in 2011.
From a historical perspective, it is not a coincidence that these examples occurred after World War II, as the end of that conflict saw the United States emerge as a global superpower with an outsized share of responsibility for the maintenance of international order, and in several of the examples cited, the use of force was justified with reference to US commitments to international organizations such as the UN or NATO. In this sense, the broad view suggests that executive power under the Constitution is not static, but rather evolves in response to historical developments.
Of course, which of the two theories is correct as a matter of constitutional law is unlikely to be conclusively determined anytime soon, as federal courts have traditionally preferred to punt on questions involving war powers, leaving them to be sorted out through the political process whenever possible.
In the absence of any clear judicial determinations one way or the other, the Department of Justice’s Office of Legal Counsel (OLC) has made considerable efforts to promote the broad theory over the years. In a series of opinions articulating the executive branch’s view of the president’s commander-in-chief powers, the OLC has developed a two-part test for evaluating a president’s decision to introduce US military forces into conflict situations without congressional authorization. Under this test, a unilateral use of force by the president must (1) serve an important national interest, and (2) not amount to “war” in the constitutional sense. For its part, Congress has never formally endorsed the OLC’s two-part test, but it has arguably given tacit acknowledgement to the fact that the president is likely to act without express approval in certain instances, as the War Powers Resolution neither expressly permits or prohibits unilateral uses of force by the president.
Did Operation Midnight Hammer Satisfy the Two-Part Test?
Given that the Trump administration appears to have relied on the two-part test in articulating its rationale for Operation Midnight Hammer, the question arises whether or not the requirements of the test were satisfied. As a practical matter, the national interest requirement has been interpreted quite permissively, and can conceivably include anything from enforcing UN Security Council resolutions to preventing humanitarian catastrophe. As it pertains to Operation Midnight Hammer, President Trump did not actually specify what national interests were served by the operation, merely noting that the strikes were carried out to “advance vital United States national interests.” That said, it is a safe assumption that the national interests the president had in mind included the defense of Israel and preventing Iran from acquiring a nuclear weapon. While we can certainly debate the wisdom of the underlying policies informing these justifications, they are not beyond the pale of what the OLC has considered to be within the national interest for purposes of the two-part test in past opinions. It follows that the second of the two requirements—that the use of force cannot amount to ‘war’ in the constitutional sense—is the more significant one.
To determine whether or not a potential use of force would cross the threshold into war, the OLC evaluates the “anticipated nature, scope and duration” of the use of force. Also relevant is whether the use of force is likely to result in “prolonged and substantial military engagements” or the “exposure of US military personnel to significant risk over a substantial period.” The greater the likelihood that the contemplated use of force will result in either eventuality, the more it begins to look like war, and would thus require authorization by Congress. With regards to the first prong, president Trump maintains that the strikes were limited in scope and purpose, as they singled out Iranian nuclear facilities and did not target Iranian troops or military facilities. Regarding the second prong, he notes that the operation was “planned and executed in a manner designed to minimize casualties, deter future attacks, and limit the risk of escalation.” He also notes that no US ground forces were involved in the strikes.
So far at least, this analysis appears to hold up. There have been no subsequent strikes on Iranian territory by the US since June 21st. Neither have US military personnel been exposed to any significant danger beyond a series of symbolic Iranian strikes on US bases (which Iran notified the US of ahead of time, presumably so as to avoid any casualties).
A post-hoc analysis of the operation is only one part of the equation, however. Also relevant is the question of whether the strikes could have resulted in a dramatically different outcome. In other words, although Operation Midnight Hammer does not appear to have crossed the threshold into ‘war’ under the OLC’s two-part test, was there a significant risk that it could have?
To be sure, Iran’s military power does not come remotely close to rivaling that of the US But Iran is doubtless a regional power with a sizable military equipped with ballistic missiles capable of striking US military bases throughout the Middle East. Had Iran chosen to retaliate by striking US military installations without warning, or had any US military personnel been killed as a result of Iran’s retaliatory strikes, it is conceivable that the situation could have quickly escalated into a more substantial conflict. Iran’s proxy network could also factor into the analysis here, especially given Iran’s preference for retaliation through asymmetric means over the long term. While these facts may not alter one’s conclusion under the OLC two-part test, they certainly place Iran in a different category than other states where the president has authorized unilateral strikes in recent years (such as Libya or Syria), and thus warrant careful consideration. Whether the OLC will provide a more substantial explanation as to how it factored these considerations into its analysis remains to be seen.
Conclusion
In sum, Operation Midnight Hammer was almost certainly unconstitutional under a narrow theory of executive power, which precludes the OLC two-part test. Under the broad theory (which does include the OLC framework), there are arguments both ways, with the key question being the likelihood that a strike on Iran’s nuclear facilities could have caused a more substantial conflict that crossed the threshold into ‘war.’ Because the courts are unlikely to decide any of these issues on justiciability grounds, however, it would ultimately fall to Congress to signal its view that President Trump exceeded the scope of his authority under Article II, either through a joint resolution under the War Powers Resolution or legislation that cuts off funding for any further use of force against Iran without express authorization. While a number of resolutions to this effect were introduced in the House and the Senate in the weeks following Operation Midnight Hammer, as of the time of this writing, none of the proposed resolutions have been enacted into law. Unless that changes, Operation Midnight Hammer was likely de facto constitutional if not de jure.
Matthew Pheneger is a practicing attorney with a JD from Case Western Reserve University in Ohio, where he was a Vattel International Law scholar at the Cox Center for International Law.
