This was first published in Just Security.
Last month, Representative Elaine Luria published an op-ed advocating for the adoption of an authorization for use of military force (“AUMF”) “to secure and protect Taiwan” from the People’s Republic of China. There are many grounds on which to criticize Luria’s proposal. Still, the premise of her op-ed warrants serious discussion: As she writes, “the president has no legal authority, without the express authorization of Congress, to use military force to defend Taiwan.”
Some disagree with this assessment of the legal landscape. Julian Ku, a constitutional and international law scholar, suggested that President Joe Biden could bypass the need for congressional authorization by invoking his constitutional prerogative to use military force to protect the “national interest.” Building on a string of precedents dating to the 1940s, the Obama administration used the national-interest theory to justify its unilateral action in Libya. Ku astutely observed that some of the same lawyers who crafted the Libya arguments now serve in the Biden administration.
There may well be lawyers in the Biden administration who believe that the president has broad authority to use force without congressional authorization. But the national‑interest arguments for intervention in Libya do not apply equally to the situation in Taiwan.
Although it is not the focus of this piece, it has been argued that any operation to protect Taiwan would “almost certainly” rise to the level of “war in the constitutional sense,” based on the probable nature, scope, and duration of the engagement. The Declare War Clause would then foreclose unilateral presidential action, as a recognized “constitutionally-based limit” on how the president uses force without congressional authorization.
Moreover, and as this article explains, the national-interest theory of presidential war-making would not justify unilateral military action to protect Taiwan. This theory is on dubious footing to begin with, and it has been stretched thin by a series of increasingly tenuous invocations. But even on its own terms, the theory calls for some congressional recognition of the national interest at stake. That recognition is missing here; indeed, Congress, through two pieces of legislation, has already disapproved of unilateral action to protect Taiwan.
Unilateral Action in the “National Interest”
Article I of the Constitution grants Congress, not the president, the power to declare war. But historically, the president has been understood as having an inherent, Article II authority to protect the nation from attack, even without prior congressional approval. As early as 1801, during the First Barbary War, President Thomas Jefferson unilaterally dispatched frigates to liberate U.S. merchants who had been detained and ransomed by the Barbary States.
It is well established, however, that the president’s constitutional prerogative is defensive, not offensive. After securing the safe passage of the detained merchants, Jefferson requested permission from Congress to undertake “measures of offense” against the Barbary States, as he was “[u]nauthorized by the Constitution, without the sanction of Congress, to go beyond the line of defense.”
The divide between offense and defense may seem simple, even intuitive, but the national-interest theory obscures the boundary line. Under the national-interest theory — which no court has ever ratified — the president has Article II authority to “employ military force in defense of important national interests.” In other words, the president can unilaterally defend the nation not only from attack, or direct threat of attack, but also from other types of threats that involve little or no risk of an attack on U.S. territory or citizens. The evolution of the national-interest theory shows how unmoored and untenable this broad reading of presidential power can be — but also underscores that Congress maintains an important role in the national-interest analysis.
The Department of Justice (“DOJ”) first articulated the national-interest theory in May 1941, shortly before the United States entered World War II. Understanding the broad implications and potential reach of the War, the Roosevelt administration was eager to train British flying students at U.S. Army Air Corps facilities. Congress, though, had not authorized the Air Corps to provide this particular form of assistance to the British. Notwithstanding this omission, then-Attorney General Robert Jackson concluded that President Franklin D. Roosevelt could offer the training pursuant to his Article II power as Commander in Chief.
Jackson’s analysis, much like his later concurrence in Youngstown Sheet & Tube Company v. Sawyer, recognized the possibility of concurrent presidential and congressional authority over military action. First, Jackson noted that “the President’s authority [had] long been recognized as extending to the dispatch of armed forces . . . for the purpose of protecting American lives or property or American interests” (emphasis added). He then observed that Congress had not forbidden the training in question, and he assumed for argument’s sake that Congress had not expressly authorized it either (a state of affairs that would have placed the president’s desired action in “zone 2” of Jackson’s Youngstown framework). He nonetheless found it significant that “Congress [had] explicitly enunciated the policy that the defense of certain countries  at war, including Great Britain, [was] vital to our own defense and that the furnishing of aid to such countries [was] essential to the security of the United States.”
Jackson effectively established a two-pronged test, whereby the combination of (1) the president’s power to protect national interests and (2) Congress’s prior recognition of the pertinent interests enabled President Roosevelt to use the Air Corps without explicit authorization.
The national-interest theory was again invoked in 1992, when President H.W. Bush deployed U.S. Armed Forces to Somalia in support of a United Nations humanitarian aid and peacekeeping mission. The H.W. Bush administration located its authority primarily in the “national interests [of] protecting the lives of Americans overseas,” who were then assisting the United Nations through U.S. government and private initiatives. In addition, the administration cited a history of presidents recognizing the United Nations as the linchpin of the “new world order” and a State Department memorandum from the Korean War that concluded that the “continued existence” and “effective[ness]” of the United Nations was a “paramount United States interest.”
In endorsing the protection of overseas Americans and the effectiveness of the United Nations as national interests justifying the deployment of troops, the administration did not cite any congressional statements. But it was still careful to look for some sign of congressional support for U.S. involvement in Somalia. By over-reading the Horn of Africa Recovery and Food Security Act, the administration concluded that “Congress appears to have contemplated that the President might find it necessary to make use of military forces to ensure the safe delivery of humanitarian relief in Somalia.” The administration’s national interests were thus ostensibly legitimized, however indirectly, by congressional backing.
Three years later, the Clinton administration based its 1995 deployment of ground forces to Bosnia — seemingly an offensive, not defensive, use of force — on the “important national interest” of supporting “a NATO operation that carries out a peace agreement supported by the United Nations.” Not only had Congress failed to recognize this interest, but the Senate had recently expressed its sense that a “United Nations Security Council Resolution . . . does not constitute authorization for the deployment of United States Armed Forces . . . under the Constitution.” The Department of Justice ignored this inconvenient fact. Still, when citing a secondary interest in “preserving peace in [the Balkans] and forestalling the threat of a wider conflict,” DOJ made a thin attempt to honor Jackson’s two-pronged test, noting that Congress had recognized “ethno-religious conflict in Central and Eastern Europe” as one of several “new, more diverse challenges” facing the United States and its allies.
The next expansion of the national-interest theory occurred during the Obama administration, which decided in a still-undisclosed opinion that “prevent[ing] genocidal acts against the Yazidis” in Iraq could be a sufficient national interest. Relying on the Obama-era opinion, the Trump administration in 2018 cited a generalized “national interest in mitigating a humanitarian crisis” to justify a series of unilateral attacks on chemical weapons facilities in Syria. And the Trump administration added a new, freestanding national interest of its own: “deterrence of the use and proliferation of chemical weapons.” Paying lip service to Jackson’s two‑pronged analysis once again, the administration noted that Congress had cited Iraq’s “large stockpiles of chemical weapons” as one of the bases for enacting the 2002 AUMF against Iraq and that the Senate had ratified the Chemical Weapons Convention.
Taking stock of this history, two things stand out. First, once an administration identifies a supposed national interest, successive administrations will continue to use it, devoid of the original context in which it was identified. The H.W. Bush administration’s interest in supporting the United Nations in Somalia transitioned into the Clinton administration’s interest in supporting NATO in the Balkans. The Obama administration’s interest in preventing genocidal acts against the Yazidis morphed into preventing crimes against humanity committed by Syria. To use a recently coined term, this is “law creep,” and both the executive and legislative branches need to be cognizant of how their broad pronouncements may develop a life of their own in the hands of future administrations.
Second, and more important, successive administrations have recognized that Congress’s perception of a national interest matters. Executive branch lawyers have played fast and loose with what Congress says, and they may disregard non-binding statements made by a single chamber of Congress, but Jackson’s two-pronged framework hobbles on. A claim of national interest that is completely devoid of legislative support is on shaky footing, even by DOJ standards.
Furthermore, Congress always has the option of explicitly prohibiting military action, shifting the analysis from “zone 2” of Youngstown’s tripartite framework (the grey area in which Congress has neither authorized nor prohibited the president’s action) to “zone 3” (where Congress has prohibited the action and the president’s power is at its lowest ebb). Whatever one thinks of the reasoning in the Obama administration’s Libya opinion, the opinion at least acknowledges that the “independent authority of the President” to conduct unilateral operations may be “specifically restricted” by Congress.
Congress’s Prior Statements Regarding Taiwan
Congress has not provided legislative support for intervening militarily in Taiwan. To the contrary, through its repeal of the Formosa AUMF (described below) and its adoption of the Taiwan Relations Act, Congress has opposed any unilateral use of force to protect Taiwan from the People’s Republic of China. And Congress has held steadfast to this opposition, referencing the Taiwan Relations Act across its recent legislation.
The Formosa AUMF was enacted in 1955, during the Eisenhower administration. Similar to the AUMF that Rep. Luria now calls for, the Formosa AUMF authorized the president “to employ the Armed Forces of the United States as he deems necessary for the specific purpose of securing and protecting Formosa [Taiwan]” from the People’s Republic of China. It was never used to mobilize U.S. forces. In 1974, as the United States moved toward normalizing relations with the People’s Republic of China and Congress repealed the AUMF, revoking the president’s authority to use force in Taiwan.
Five years later, Congress enacted the Taiwan Relations Act. That Act instructs that the president and Congress shall “make available to Taiwan such defense articles and defense services . . . to enable Taiwan to maintain a sufficient self-defense capability.” But, as Rep. Luria says, it explicitly stops short of permitting the use of force to protect Taiwan. Instead, it instructs that if there is “any threat to the security or the social or economic system of the people on Taiwan and any danger to the interests of the United States arising therefrom,” the president must promptly report the threat and danger to Congress. Then, “[t]he President and Congress shall determine . . . appropriate action by the United States in response.” Any use of force to support Taiwan must be decided upon jointly by the president and Congress.
Congress’s position has not changed in the intervening years. Although the 2018 Taiwan Travel Act acknowledges that “peace and stability in the Western Pacific area are in the . . . interests of the United States,” it also recognizes that the Taiwan Relations Act, with its limitation on unilateral decision-making, is “an anchor for peace and security” in the region. Likewise, the 2018 Asia Reassurance Initiative Act recognizes that it is “the policy of the United States” to “faithfully enforce” any U.S. commitments to Taiwan in a manner that is “consistent with the Taiwan Relations Act” and contemporaneous communiques with both China and Taiwan.
Executive branch lawyers operating in good faith would not be able to invoke the national-interest theory with respect to a use of force against China in defense of Taiwan. In legislation specifically focused on defending Taiwan, Congress has made clear that unilateral military action is not in the national interest.
My personal view is that we should not initiate a conflict with the People’s Republic of China. Such a conflict would have unforetold human and environmental consequences. Nevertheless, Rep. Luria and I agree on a fundamental part of this discussion. Any use of force to protect Taiwan must be expressly authorized by Congress, and only after both political branches of this country have reckoned with the costs and implications of launching into hostilities with a global power.