The Constitutional Power to Threaten War

            In September 2012, prodded by Israeli Prime Minister Benjamin Netanyahu’s urging, American policy-makers and commentators argued intensely about whether the President of the United States should draw a “red line” for Iranian leaders – a threshold of nuclear weapon development the crossing of which would trigger a U.S. military response. It is easy to imagine that the actual launching of military attacks against Iran would generate intense scrutiny and argument of constitutional issues, most notably whether the President could take this action without congressional consent.  Were those military strikes to carry on for months, it is also easy to imagine significant legal discussion of whether the President could continue them, in light of the War Powers Resolution’s 60-day limit on military engagements without express congressional authorization. Nobody seriously questioned, though, that as a constitutional matter the President could unilaterally draw the red line threatening them. The implicit consensus that the President is constitutionally empowered to threaten military force in this situation is, in my view, correct, but it presents an anomaly: proponents of drawing that line argued that doing so was necessary to prevent a war (or at least a bigger and more destructive war) down the road, while critics argued that it would needlessly provoke or drag the United States into a war — the very sorts of concerns that usually animate strident war powers debates.  More generally, the allocation of constitutional war powers is thought to be of paramount import because it could affect whether or when the United States goes to war and it implicates core questions about how our democracy should decide matters of such consequence. Yet legal discourse in this area excludes almost completely some central ways in which the United States actually wields its military power, namely, with threats of war or force.  This Article breaks down that barrier and connects the legal issues with the strategic ones. As to the constitutional issues, there is wide agreement among legal scholars on the general historical saga of American war powers – by which I mean here the authority to use military force, and not the specific means or tactics by which war is waged once initiated – though there remains intense disagreement about whether this is an optimistic or pessimistic story from the perspective of constitutional values and protection of American interests.  Generally speaking, the story goes like this:  The Founders placed decisions whether actively to engage in military hostilities in Congress’s hands, and Presidents mostly (but not always) respected this allocation for the first century and a half of our history.  At least by the Cold War, however, Presidents began exercising this power unilaterally in a much wider set of cases, and Congress mostly allowed them to; an effort to realign legislatively the allocation after the Vietnam War failed, and today the President has a very free hand in using military force that does not rise to the level of “war” (in constitutional terms, which is usually confined to large-scale and long-duration uses of ground forces). From a functional standpoint, this dramatic shift in constitutional power is seen as either good, because decisions to use force require policy dexterity inherent in the presidency, or bad, because unilateral presidential decisions to use force are more prone than congressionally-checked ones to be dangerously rash. With this story and split in resulting views in mind, lawyers and legal scholars continue to debate a series of familiar constitutional questions:  Does the historical gloss of practice among the political branches – the patterns of behavior by the President and Congress with respect to using force – provide legal justification for this shift toward executive power?  Without requiring congressional authorization before engaging in hostilities, are there sufficient checks on executive action?  Does this shift in power lead the United States into needless and costly wars, and if so should it be remedied with more potent checks, whether led by Congress or courts, to reestablish a constitutional formula closer to the original one? The main data set for analyzing these questions is, not surprisingly, actual wars and other hostile engagements of U.S. forces abroad.  In ascertaining and describing the patterns of executive behavior and congressional responses, legal scholars look at armed conflicts and combat operations of the past.  Legal debates heat up during or following wars, especially major ones that go badly, or military combat that extends longer than expected.  Proposed solutions focus on the commencement of armed hostilities – military engagement with the enemy – and what, if any, inter-branch actions must precede or accompany it. There is a major disconnect here, though, between legal analysis and scholarship of constitutional war powers – specifically, its predominant focus on actual military engagements – and the way the United States wields its military might, especially since the onset of the Cold War and extending into the 21^st century.  Often times the most important policy tool derived from U.S. military power is not waging war – it is threatening war or force.  The power to threaten war is closely related to, but analytically distinct from, the power to make it. By “threats” in this Article I mean communicating the will and capability to use military force, as a way to induce other actors to change behavior – whether to do something or to not do something.  During major periods of American history, including the present one, U.S. strategy relied heavily on perceptions of U.S. military might and willingness to use it; that is, it has relied on the manipulation of risk to deter aggression or other actions by adversaries, to coerce or compel certain actions by other states or international actors, to reassure allies, and to pursue other political designs under the shadow of armed threats.  The primary purpose to which U.S. military might has been directed since World War II has generally been to prevent wars or avoid them; when wars or large-scale force was actually used, it was because a prior policy or strategy had failed, for instance, deterrent threats were insufficiently credible, crises involving U.S. threats of force escalated in ways difficult to control, and so on – not because making war was intended as the best approach to a danger or sometimes even that it was the expected result.  In this regard, most of the time that U.S. military power is “used” – and often when it is most successful – it does not manifest as a war or major military engagement at all. Put another way, there is a basic paradox at work here, that if threats of force work, force does not have to be used (at least not “used” in the sense that constitutional lawyers’ think about it).  Other things being equal, in theory the greater the credibility of the threat, the less likely it will be necessary to make good on it.  Because this argument is about wars that don’t happen, though, it is difficult to develop empirical evidence to support it.  Accordingly, statesmen cannot be so sure of its validity and constitutional lawyers’ tend to overlook it entirely. There is a close parallel to this disconnect between legal discourse and security strategy in international law.  Article 2(4) of the UN Charter prohibits “the threat or use of force against the territorial integrity or political independence of any state.”  However, legal doctrine is not at all well developed with respect to threats beyond prohibiting the most blatantly aggressive ones, nor is the regulation of threats of force well theorized in legal scholarship.  As with domestic law of American war powers, the threat element has mostly disappeared from discussion, even though international relations scholars recognize that threatened force is doing so much work. This Article is not a doctrinal argument.  It is an argument about framing and method, intended to fill an analytical gap and therefore to inform understanding of the functional advantages and disadvantages of legal formulas for allocating war powers. Specifically, Part I of this Article contends that understanding evolution in constitutional war powers and the merits or dangers of these developments requires widening the data set and investigative lens to include threats of force and incorporating the insights of the past several decades’ analysis by political scientists and scholars of American grand strategy.  Doing so reveals aspects of the war powers story obscured by legal discourse and method focused predominantly on actual uses of force, and it alters and refines the orthodox functional arguments usually relied on by both sides – presidentialist (favoring vast unilateral executive authority to use force) and congressionalist (favoring tight legislative checks on that authority) – of the war powers debate.  Most notably, and putting in game-theoretic terms, the debate between presidentialist and congressionalist legal scholars about functional advantages takes place only at the final stage of the decision tree; but the President’s ability to threaten force is critically important at earlier stages in determining whether that final stage will even occur at all. Part II draws on several strands of political science literature to illuminate the relationship between war powers law and threats of force.  As a descriptive matter, the swelling scope of the president’s practice in wielding threatened force largely tracks the standard historical narrative of war powers shifting from Congress to the President.  Indeed, adding threats of force to that story might suggest that this shift in powers of war and peace has been even more dramatic than usually supposed, at least in terms of how formal congressional checks are exercised. Part II also shows, however, that congressional checks and influence – even if not formal legislative powers – operate more robustly and in different ways to shape strategic decision-making than usually supposed in legal debates about war powers, and that these checks and influence can enhance the potency of threatened force. This Article thus fits into a broader scholarly debate now raging about the extent to which the modern President is meaningfully constrained by law, and in what ways. Recent political science scholarship suggests that Congress already exerts constraining influences on presidential decisions to threaten force, even without resorting to binding legislative actions. Moreover, when U.S. security strategy relies heavily on threats of force, credibility of signals is paramount.  Whereas it often used to be assumed that institutional checks on executive discretion undermined democracies’ ability to threaten war credibly, some recent political science scholarship also offers reasons to expect that congressional political constraints can actually bolster the credibility of U.S. threats. As a prescriptive matter, Part II also shows that examination of threatened force and the credibility requirements for its effectiveness calls into question many orthodoxies of the policy advantages and risks attendant to various allocations of legal war powers, including the existing one and proposed reforms.  Most functional arguments about war powers focus on fighting wars or hostile engagements, but that is not all – or even predominantly – what the United States does with its military power.  Much of the time it seeks to avert such clashes while achieving its foreign policy objectives: to bargain, coerce, deter.  The President’s flexibility to use force in turn affects decision-making about threatening it, with major implications for securing peace or dragging the United States into conflicts.  Moreover, constitutional war power allocations affect potential conflicts not only because they may constrain U.S. actions but because they may send signals and shape other states’ (including adversaries’) expectations of U.S. actions. That is, most analysis of war-powers law is inward-looking, focused on audiences internal to the U.S. government and polity, but thinking about threatened force prompts us to look outward, at how war-powers law affects external perceptions among adversaries and allies. Here, extant political science and strategic studies offer few clear conclusions, but they point the way toward more sophisticated and realistic policy assessment of legal doctrine and proposed reform. More generally, as explained in Part III, analysis of threatened force and war powers exposes an under-appreciated relationship between constitutional doctrine and grand strategy. Instead of proposing a functionally optimal allocation of legal powers, as legal scholars are often tempted to do, this Article in the end denies the tenability of any such claim.  Having identified new spaces of war and peace powers that legal scholars need to take account of in understanding how those powers are really exercised, this Article also highlights the extent to which any normative account of the proper distribution of authority over this area depends on many matters that cannot be predicted in advance or expected to remain constant.  Instead of proposing a policy-optimal solution, this Article concludes that the allocation of constitutional war powers is – and should be –geopolitically and strategically contingent; the actual and effective balance between presidential and congressional powers over war and peace in practice necessarily depends on fundamental assumptions and shifting policy choices about how best to secure U.S. interests against potential threats.