Oona A. Hathaway[*]
[This essay is available in PDF at this link]
The last several decades have witnessed a dramatic decline in the capacity of the U.S. Congress to constrain the president’s unilateral decisions to send the United States to war. That erosion of congressional authority has accelerated since the terrorist attacks of September 11, 2001. Today, Congress’s ability to limit the exercise of presidential decisions to deploy force abroad is highly constrained. Presidents of both parties have expansively interpreted presidential authority to make decisions to use force, and Congress has proven unable or unwilling to insist on playing its formal constitutional role in response. Courts, meanwhile, have stood back and allowed this accretion of power to take place unabated. On the rare occasion that they have been asked to intervene, courts have almost always refused, relying on a variety of justiciability doctrines.[1] As a result, the president today has had unprecedented free reign to decide when, where, and how to deploy armed force on behalf of the United States.
During the last two decades, one of the most notable trends to result from this largely unbridled presidential power over the decision to go to war is an ever-expanding reliance on the principle of “self-defense.” The reliance on self-defense by the president serves two purposes: It allows the president to paper over weaknesses in the congressional authorizations for use of force with a general reference to the president’s Article II powers to defend the nation. It also allows the president to make claims that sound in the register of international law—specifically the Article 51 self-defense exception to the United Nations Charter’s general prohibition on unilateral resort to force by states.[2]
This Article argues that these ever-expanding claims to act in “self-defense” have had the effect, perhaps unintended, of eroding the international law prohibition on the use of force—and not just for the United States. The prohibition on the unilateral resort to force by states under the 1945 UN Charter was designed to be highly restrictive, undergirding the creation of a new legal order in which might no longer made right. Article 51 offered a very limited exception to states to resort to force without Security Council authorization in cases where a state had come under an “armed attack.”[3] Enabled by the loose limits on presidential war powers, the United States has gradually expanded its claims to self-defense under Article 51. The consequence has been not only erosion of congressional authority, but also erosion of the international law limits on unilateral resort to force. After all, the United States, which drafted the UN Charter and holds one of five permanent seats on the UN Security Council, has played an outsized role in the creation and evolution of international law during the entire postwar era. Hence, whenever the United States makes novel or marginal claims to the right to use force under international law in “self-defense” or “collective self-defense” under Article 51, it offers up arguments to other states who may wish to capitalize on the legal space that the United States’ claims create. In this way, the erosion of U.S. law constraining unilateral presidential war power has had a direct effect—and a corrosive one—on the international law constraining the use of force under the United Nations Charter.
The essay begins in Part I by documenting the erosion of U.S. constitutional constraints on the power of the president to wage war. Part II examines the impact of this erosion on interpretations of Article 51 of the United Nations Charter—which provides that states may respond in self-defense or collective self-defense to an armed attack. Part III concludes by calling on Congress to reassert its war powers—not simply to defend its proper constitutional role but also to stem the erosion of international legal limits on the use of armed force.
[*] Gerard C. and Bernice Latrobe Smith Professor of International Law at Yale Law School. My thanks to participants in the 2022 Chicago-Virginia Foreign Relations Roundtable for their feedback on this essay. My thanks, too, to the 2019 Texas National Security Review Policy Roundtable: The War Powers Resolution, where I began to develop some of these ideas.
[1] For example, the U.S. District Court for the District of Columbia found that the suit brought by the father of Anwar al-Aulaqi challenging al-Aulaqi’s targeting by the U.S. Department of Defense could not go forward because the plaintiff lacked standing and his claims were non-justiciable under the political question doctrine. Al-Aulaqi v. Obama, 727 F.Supp.2d 1, 49–50 (D.D.C. 2010). The same court dismissed a suit by a member of the armed forces who challenged the legality of the U.S. military operations against ISIS. Smith v. Obama, 217 F. Supp. 3d 283 (D.D.C. 2016) (dismissing on standing and political question grounds), order vacated, appeal dismissed sub nom. on other grounds, Smith v. Trump, 731 F. App’x 8 (D.C. Cir. 2018) (vacated on mootness grounds, because Captain Smith had by then tendered an unqualified resignation from active duty). In addition, a line of cases has all but foreclosed the idea that an individual member of Congress or group of members can assert legislative standing to maintain a suit against a member of the Executive Branch. See, e.g.,Kucinich v. Obama, 821 F.Supp.2d 110, 124 (D.D.C. 2011); Raines v. Byrd, 521 U.S. 811 (1997); Chenoweth v. Clinton, 181 F.3d 112 (D.C. Cir. 1999); Campbell v. Clinton, 203 F.3d 19 (D.C. Cir. 2000). For a more complete list of cases through 2012, see generally Michael John Garcia, War Powers Litigation Initiated by Members of Congress Since the Enactment of the War Powers Resolution, Cong. Res. Serv. (2012), https://sgp.fas.org/crs/natsec/RL30352.pdf [https://perma.cc/2QS6-ALEZ]. The courts were not always so reluctant to reach the merits of such cases, but that changed in the 1970s and 1980s. See, e.g., Carlin Meyer, Imbalance of Powers: Can Congressional Lawsuits Serve as Counterweight?, 54 U. Pitts. L. Rev. 63 (1992). For more on the dynamics that have led to few constraints on presidential power over national security decisions, see Oona A. Hathaway, National Security Lawyering in the Post-War Era: Can Law Constrain Power?, 68 UCLA L. Rev. 2 (2021).
[2] U.N. Charter, arts. 2(4) & 51.
[3] Adil Ahmad Haque, The United Nations Charter at 75: Between Force and Self-Defense — Part One,Just Security (June 24, 2000), https://www.justsecurity.org/70985/the-united-nations-charter-at-75-between-force-and-self-defense-part-one/ [https://perma.cc/H8YF-65K8].
Gerard C. and Bernice Latrobe Smith Professor of International Law at Yale Law School.