For much of American history, the system seemed to work. From the founding of the Republic to the mid twentieth century, most major uses of force received formal sanctioning by both Congress and the president. While presidents occasionally pressed outward on the boundaries of their constitutional authority—James Polk orchestrated a series of military provocations along the Texas border that would launch the Mexican-American War, and Lincoln wielded extraordinary extra-constitutional powers during the Civil War—Congress’s rightful place in deliberations over war appeared reasonably well established. With Harry Truman, however, this would change. By declaring the Korean War a “police action” that did not require a declaration of war, Truman established a precedent for subsequent presidents to strike out on their own, deploying the military on prolonged tours of duty, humanitarian ventures, and targeted strikes without ever securing Congress’s formal consent.

Truman’s presidency coincided with the nation’s emergence as a genuine superpower. At the close of World War II, the United States stood as the world’s strongest military and economic power, with new interests to protect and promote in even the most distant reaches of the globe. Isolationists no longer ruled U.S. foreign policy. Indeed, the Founders could hardly have imagined the awesome influence that America would wield in international affairs, and the pressures that this would place on the commander in chief. A dangerous new world, many would argue, required powerful, determined, and rapid responses that only a president could manufacture.

By Richard Nixon’s second term, the White House war machinery seemed out of control. Presidents had long initiated military operations without a formal declaration of war, but now they were doing so without the faintest recognition of Congress’s rightful authority. Faced with dubious claims about North Vietnamese attacks on U.S. ships in the Gulf of Tonkin, the conduct of a secret war in Laos, and the persistence of an illegal bombing campaign in Cambodia, political observers at the time began to cry foul. In a celebrated indictment of what he called an “imperial presidency,” Arthur Schlesinger noted that “by the early 1970s the American President had become on issues of war and peace the most absolute monarch (with the possible exception of Mao Tse-tung of China) among the great powers of the world.”¹ Plainly, something needed to be done.

The 1973 War Powers Resolution was supposed to rein in a presidency run amok and to reassert congressional prerogatives over foreign policy making. It required that presidents “in every possible instance” consult with Congress before introducing military forces into foreign hostilities, secure formal authorization within sixty to ninety days or withdraw troops, and if the military engagement was approved by Congress, submit regular reports to that body. The resolution, its advocates claimed, would correct the decades-long presidential incursions into congressional war powers and put members of Congress back in charge of deliberations involving the use of military force, as the Framers intended them to be. At its signing, cosponsor senator Jacob Javits (R-NY) announced that “never in the history of this country has an effort been made to restrain the war powers in the hands of the president . . . [This bill] will make history in this country such as has never been made before.”² With this resolution, congressional aspirations to reclaim lost ground in an age-old struggle over who has the right to declare war had peaked.

Instead of firmly reasserting congressional prerogatives, however, the resolution brought disappointment. Every president since Nixon, Democrat and Republican, has refused to recognize its constitutionality. In the last three decades, presidents have launched one military initiative after another—in Grenada and Haiti and Lebanon and Panama and Kosovo and Liberia—without ever securing congressional authorization. Only once, for Lebanon in 1983, has the War Powers clock even been started, and then the president was granted an eighteen-month grace period. And when launching smaller-scale military operations, presidents frequently have dodged the resolution’s reporting requirements. Rather than correcting for gross imbalances in the nation’s system of separated powers, the War Powers Resolution, astonishingly, turned bad to worse.

On this, almost everyone agrees. According to Robert Katzman, “A growing consensus maintains that the War Powers Resolution has not worked as Congress envisioned. Presidents have refused to invoke the law in ways that could limit their freedoms of action; indeed, they have not even conceded its constitutionality. Congress, for its part, has been reluctant to challenge the president.”³ According to John Hart Ely, “Thanks to a combination of presidential defiance, congressional irresolution, and judicial abstention, the War Powers Resolution has not worked.”⁴ Observes Peter Irons, “Every president since Nixon has disregarded—and in some cases flatly disobeyed—the provisions of what has become a monument to legislative futility.”⁵ The resolution, says Louis Fisher, “was a sellout, a surrender.”⁶

As Congress’s best effort to reclaim control over military affairs, the resolution’s failings would seem to reflect all of the inadequacies of the institution that enacted it. According to Stephen Weissman, in matters involving war, Congress is infected by a “culture of deference: a distinct set of norms and beliefs, customs and institutions, that confine it to the margins of power.”⁷ And this culture of deference—if indeed it is a “culture”—sabotages the machinery of government more generally. Ely rails against “the disappearance of the separation of powers, the system of checks and balances, as it applies to decisions to go to war.”⁸ Claiming that “legislative abdication is the reigning modus operandi” in foreign affairs, and that Congress’s involvement in decisions involving war has been “decimated,” Neal Katyal suggests that we abandon our focus on Congress and instead look to independent executive agencies to check presidential war powers.⁹ According to Joanne Gowa on matters involving war, Congress and the president adhere “to a tacit truce [as] a means to escape rather than a reflection of accountability,” the result of which is “a subversion of a checks-and-balance system.”¹⁰ In their indictment of Congress’s failures to oversee the president’s prosecution of foreign wars, Norman Ornstein and Thomas Mann conclude that, “In the past six years . . . congressional oversight of the executive across a range of policies, but especially on foreign and national security policy, has virtually collapsed.”¹¹

With the erosion of congressional checks on presidential war powers, these scholars note, comes the erosion of our system of separated powers. There emerges, then, an unconstrained president who launches military forces at will, perhaps attentive to his place in history or to the international balance of powers, but liberated from the congressional interference that so often foils his domestic policy initiatives. As Louis Fisher characterizes the post-Truman presidency, “On matters of war, we have what the framers thought they had put behind them: a monarchy. Checks and balances? Try to find them.”¹²

This book accepts Fisher’s challenge. It searches for congressional efforts to constrain presidential war powers during the post–World War II era, and in so doing, it discovers considerable evidence that checks and balances, though diminished, persist nonetheless. There is no denying that Congress has abdicated considerable responsibilities over war making, or that presidents have stepped into the fray and claimed powers and rights that the Framers never intended them to hold. But a closer look reveals more activity and more influence than scholars have been willing to admit. By broadening the scope of inquiry, and by distinguishing what is from what should be, one discovers evidence that Congress—imperfectly, intermittently, but remarkably predictably—continues to monitor the presidential use of force. More than occasionally, its members do things, or threaten to do things, that materially affect presidential decisions about war. And perhaps not surprisingly, those members who do the most to check presidential war powers consistently come from the ranks of the opposition party.

Using a variety of original datasets and drawing from diverse literatures within political science, this book demonstrates that Congress continues to play an important role in shaping the domestic politics that precede military action, and in influencing the willingness of presidents to embark on new ventures abroad. While the power its members wield may not satisfy every interested party, Congress’s mark is readily detectible. By staying attuned to partisan divisions between the legislative and executive branches, the efforts of each to anticipate and accommodate the other’s future actions, the challenges of coordinating a military venture, and the uncertainty and devastation wrought by war, we find considerable evidence of congressional influence. After exploring the roots and dimensions of presidential dominance in matters of war, the remainder of this chapter characterizes the various means by which members of Congress influence presidential decisions regarding military action; the subsequent chapter, then, identifies the conditions under which Congress most effectively employs them.

There is, at present, a burgeoning body of work within American politics that documents the strategic advantages presidents enjoy when they exercise their unilateral powers, or what elsewhere we have called “power without persuasion,” which very much embodies the deployment of troops abroad.¹⁴ Two features of this unilateral politics literature are worth noting. The first concerns sequence. When presidents act unilaterally, they stand at the front end of the policy-making process and thereby place on Congress and the courts the burden of revising a new political landscape. If adjoining branches of government choose not to retaliate, either by passing a law or ruling against the president, then the president’s order stands. Only by taking (or credibly threatening to take) positive action can either adjoining institution limit the president’s unilateral powers.

Members of Congress often do confront presidents when their military orders prove misguided or ill-informed. They do so, however, under less than ideal circumstances. For starters, when debating the merits of an ongoing military venture, members of Congress are vulnerable to the accusation that they are undermining troop morale and catering to the enemy. As James Lindsay recognizes, members often avoid putting themselves in “the politically and morally difficult position of allowing funds to be cut off to troops who may be fighting for their lives.”¹⁵ By way of example, recall Clinton’s deployment of troops to Haiti in 1994. Before the action, a majority of senators opposed the plan, but once troops were deployed, Congress did not attempt to force their immediate return. One political commentator surmised, “There’s bipartisan criticism of going into Haiti. There’s also bipartisan support, at least, in supporting the troops now that they’re there.”¹⁶ Though members can, and do, take on the president during the ongoing course of a military venture, they do so under conditions that hardly foster open and critical debate.¹⁷ Instead, members proceed cautiously, ever aware of how their actions and words are likely to be interpreted by a public wary of any criticism directed at troops who have willingly placed their lives on the line.

Some military actions, meanwhile, are sufficiently limited in scope and duration that Congress has little if any opportunity to coordinate an effective response, either before or during the actual intervention. In the spring of 1986, for instance, Reagan “consulted” with congressional party leaders on planned air strikes against Libya while U.S. planes were en route to Northern Africa. Obviously, there was little that these members could do to curb these attacks. As one Democrat attending the meeting noted, “What could we have done? . . . Told [the president] to turn the planes around?”¹⁸ The military completed its bombing campaign long before members of Congress could possibly have resolved their differences and enacted authorizing legislation. Though Congress might have passed legislation either supporting or condemning the president’s action after the fact, its members could do precious little to redirect the course of this particular targeted military strike. By seizing the initiative and unilaterally deploying the military to perform short and small attacks, presidents often elude the checks that Congress might otherwise place on them.

The second feature of unilateral powers that deserves attention is that when the president acts, he acts alone. Of course, he relies on numerous advisors to formulate the policy, to devise ways of protecting it against congressional or judicial encroachment, and to oversee its implementation. But to issue the actual policy, as either an executive order or memorandum or any other kind of directive, the president need not rally majorities, compromise with adversaries, or wait for some interest group to bring a case to court. The president, instead, can strike out on his own, placing on others the onus of coordinating an effective response. Doing so, the modern president is in a unique position to lead, break through the stasis that pervades the federal government, and impose his will in more and more areas of governance.

In foreign policy making generally, and on issues involving the use of force in particular, this feature of unilateral powers reaps special rewards. If presidents had to build broad-based consensus behind every deployment before any military planning could be executed, most ventures would never get off the ground. Imagine having to explain to members of Congress why events in Liberia this month or Ethiopia the next demand military action, and then having to secure the formal consent of a supermajority before any action could be taken. The federal government could not possibly keep pace with an increasingly...