American political opposition to foreign wars ran so strong in the 1920s and early 1930s that some lawmakers even proposed amending the Constitution to make declaring war harder. That effort failed, but Congress used other constitutional powers less directly tied to war or the armed forces to keep America out of foreign conflicts.

Whereas World War I raised questions of when war powers ended, World War II raised questions of when they began. After conflicts broke out in Europe and Asia, President Franklin D. Roosevelt – and later Congress – began preparing to defend not just America’s physical borders but its expanded sense of security against distant threats. In doing so, the President and Congress exercised extraordinary war powers – sometimes in competition, sometimes in unison – even while the country remained formally neutral.

Japan’s December 1941 attack on Pearl Harbor and then Hitler’s declaration of war against the United States brought the country fully into World War II. On the home front, the government wielded regulatory powers on a scale even greater than during World War I, and Roosevelt advanced some of the most sweeping claims of executive war powers of any president before or since. Yet mobilization was less constitutionally dramatic than it had been in World War I, because the legal ground had shifted in the meantime: During the interwar New Deal period, Congress’s non-war powers had been interpreted so broadly that switching from peace to war no longer delivered the same constitutional jolt. Still, although defeating the fascist Axis became the nation’s greatest military triumph, victory came at a steep price for civil liberties, most notoriously in the mass incarceration of Japanese–Americans.

To keep the postwar peace, the United States used its unrivaled clout to champion a new collective security system: the United Nations (UN). In doing so, the elected branches had to reconcile binding international security commitments with war powers originally designed for American autonomy and non-entanglement. American grand strategy was pivoting, and constitutional practice would adjust with it.

Constitutionalizing Isolation, Legislating Neutrality

In the 1920s and 1930s, Americans grew deeply wary of re-engagement in distant conflicts on other states’ terms, confident in the vast oceanic moats that separated the United States from future wars in Europe or Asia. The isolationist mood intensified as the nation suffered through the Great Depression, and blocs in Congress launched efforts to keep the United States out of foreign wars. One was an unsuccessful bid to amend the Constitution itself to make it harder to declare war. The other effort was a series of legislative acts. Earlier chapters showed how both Congress and the President can shape political, diplomatic, and military conditions that make war more or less likely long before any shots are fired. In the late 1930s, lawmakers used their powers over finance and foreign commerce – not their declare-war power – to keep the United States out of future conflicts.

Little known today, the Ludlow Amendment was a radical proposal to require a national referendum before Congress could declare war. Never before had Americans seriously contemplated amending the Constitution’s allocation of war powers. Although the amendment had little real prospect of ratification, it would have pushed war powers in the opposite direction from the one they would soon take.

Today’s critics of presidential wars might view the 1917 war declaration as the procedural gold standard. A reluctant President exhausted diplomacy before making the case for war to Congress, which deliberated and voted. Yet, after the war, Representative Louis Ludlow of Indiana joined a growing chorus of Americans who believed that even the Constitution’s requirement of a congressional war declaration was too loose – and too removed from popular control. Many in this movement blamed a jingoistic press and arms profiteers for dragging the nation unnecessarily into a European war – one in which ordinary citizens paid the price while elites reaped rewards.¹ An influential 1934 book in America, Merchants of Death, began by asking: “Who – to be specific – has the power to declare war? All constitutions in the world (except the Spanish) vest the war-making power in the government or in the representatives of the people. … Why is there no ethical revolt against these constitutions?”²

The Ludlow Amendment translated that attitude into constitutional form. A draft version read that, except when the United States was invaded, “the authority of Congress to declare war shall not become effective until confirmed by a majority of all votes cast thereon in a Nation-wide referendum.”³ This idea tapped into isolationist, pacifist, and populist political movements, and it carried forward a pre-World War I Progressive turn to direct democracy. In the mid-1930s, opinion polls revealed a whopping three-quarters of Americans favored it.⁴ Polling pioneer George Gallup observed in 1939 that the conviction that entering World War I had been a mistake had become “a master-principle” of the interwar years, shaping views on neutrality, foreign lending, and even a war referendum.⁵

Roosevelt initially held his fire, but growing support for the amendment forced him to publicly oppose it. While the amendment’s backers trusted oceans and neutrality to keep the nation safe, Roosevelt believed security required credible threats of war. In opposing the measure, Roosevelt wrote to Congress that it “would cripple any President in his conduct of our foreign relations, and it would encourage other nations to believe that they could violate American rights with impunity.”⁶ In January 1938, the House voted 209-188 against a procedural resolution that would have advanced the proposal. A Senate version moved forward only fitfully and never matched the momentum of Ludlow’s House initiative.

The amendment’s opponents won this battle. Its advocates, however, had other extant constitutional powers that they could use to prevent future slides toward war.

Throughout American history, it was widely understood that Congress held the exclusive constitutional authority to take the nation from peace to war. In the 1930s, with public opinion firmly against foreign entanglements, Congress went further. Rather than merely preserve its discretion not to act, it used other Article I powers – especially over foreign commerce – to brace the country against war, showing that the Declare War Clause was just one of many levers lawmakers could pull to steer defense strategy.

In a series of laws beginning in 1935, Congress legislated a policy of neutrality toward foreign conflicts.⁷ To avoid the circumstances that had drawn the country into World War I – and to ensure that if the United States did enter a conflict, it would be on the country’s own terms – these Neutrality Acts generally prohibited selling weapons and issuing loans to belligerents. Congress, in other words, used tight controls on finance and trade to constrain war powers. These statutes also incorporated a strict interpretation of international law requiring neutral states to treat warring states equally.

As Germany remilitarized in violation of post-World War I treaties, a 1937 amendment to the Neutrality Acts loosened restrictions slightly. It allowed Americans to engage in non-military commerce with belligerents if the purchaser paid in cash and carried away the goods on their own ships. As security tensions in Europe mounted, that caveat would help cash-rich Britain and France while avoiding repetition of 1915–17, when American ships carrying supplies to Britain and France were targeted by German submarines.⁸ The 1937 amendment also prohibited Americans from traveling on the vessels of belligerent states under most circumstances and prohibited the arming of merchant vessels (beyond small arms) when engaged in trade with belligerent nations. Again, these legislative adjustments show how Congress could use its array of powers – including foreign trade powers – to pump or release brakes on American activity that could draw the United States into war.

While Congress tried to insulate the United States from foreign conflicts, violence erupted across Asia and Europe. Japan went to war against China and, aligning itself with fascist Germany and Italy, sought to assert control over a wider continental sphere. Adolf Hitler’s Germany step by step undid the restrictive settlement terms from World War I; as it rapidly rearmed, it annexed Austria and Czechoslovakia. After Germany’s invasion of Poland in September 1939, Britain and France formally declared war on Germany. The invasion of Poland moved Congress, at Roosevelt’s urging, to repeal the mandatory arms embargo of the neutrality statutes and permit arms sales on a cash-and-carry basis.

Congress’s neutrality laws did not ultimately keep the United States out of World War II. But they shaped, in Hamilton’s 1793 phrase, the “antecedent state of things” and likely delayed full American entry until Japan struck Pearl Harbor. Before that attack and any formal war declaration, U.S. involvement would unfold in stages, as the elected branches exercised their respective powers to steer the nation’s course.

Almost-War Powers

The previous world war had raised questions about when wars end and extraordinary powers recede to peacetime bounds. World War II raised questions of when wars begin and powers expand.⁹ When Japan attacked Pearl Harbor in December 1941, the United States declared war against the Axis powers: first Japan, then Germany, and Italy. But before then, while the United States was still officially at peace, Congress and the President exercised powers that in earlier eras were normally reserved for wartime.

From 1939 through 1941, the United States wasn’t at war, but it wasn’t at peace, either. United States policy delicately balanced official neutrality, preparations for war, and aid to Britain. Congress further relaxed restrictions on support for allied countries, and authorized limited measures to build up American defenses. The Executive Branch, meanwhile, steered its own path of almost-war, pulling a different set of levers. It used the President’s commander-in-chief powers and invoked statutory emergency powers – plus the bully pulpit – to prepare for war and advance a grand vision of American security. To Roosevelt, defending the nation now meant more than just securing its geographic borders, or even its hemisphere; American security demanded halting the march of hostile empires on other sides of the globe.¹⁰ In pursuit of that ambitious agenda, the Executive Branch interpreted statutes, Article II powers, and international law flexibly (some say disingenuously) to maneuver around legal obstacles.

Several episodes illustrate these interplaying congressional and presidential moves short of war: Roosevelt’s 1939 emergency declaration, Congress’s 1940 Selective Service Act, Roosevelt’s deal to send over-age Navy destroyers to Britain, and the 1941 Lend-Lease Act. Each escalating move relied on constitutional powers besides the power to make war. Yet, each event affected whether, when, and how the United States ultimately entered the conflict.

On September 8, 1939 – seven days after Germany invaded Poland and three days after he proclaimed the United States neutral in that conflict – Roosevelt declared a national emergency for “enforcing of the neutrality of the United States and the strengthening of our national defense within the limits of peacetime authorizations.”¹¹ That same day, he issued a series of executive orders, based on an array of standing statutes delegating special emergency authorities, to increase the size of the Army and Navy and allocate more funding for protecting American citizens abroad.¹² Emergency governing was familiar territory for Roosevelt, having led the country through much of the Great Depression.

Roosevelt was careful to sell this emergency as “limited”: The proclamation itself stated that “measures required at this time call for the exercise of only a limited number of the powers granted in a national emergency.”¹³ Columnist Arthur Krock observed that the designation was meant “in part to bring the country easily and gradually toward the total emergency psychology.”¹⁴ At a press conference, the President worked to head off “scarehead stories” and stressed that the executive orders issued that day were just a few “simple and minor things within peacetime authorizations.”¹⁵ The term “limited emergency” had no statutory grounding; it was a rhetorical device to signal Roosevelt’s restraint in choosing which crisis powers to employ. Only later, as the European war escalated, would he proclaim an “unlimited” national emergency and draw on a far broader set of standing authorities to mobilize the military and expand defense production.

In late Spring 1940, Roosevelt also moved to supply Britain and France (shortly before Germany overran the latter) with critical war materiel.¹⁶ The President was starting to engage privately in coalition war-planning with British Prime Minister Winston Churchill – itself an exercise of expansive presidential war powers for a new era of American global clout – even though the United States was not (yet) a belligerent. As he did so, Roosevelt escalated his political attacks on American neutrality. “Some indeed still hold to the now somewhat obvious delusion,” he charged in a June 10 speech, “that we of the United States can safely permit the United States to become a lone island, a lone island in a world dominated by the philosophy of force.”¹⁷ To protect itself, he urged, the United States needed to help Britain make a stand.

In advancing that policy, Roosevelt relied on creative lawyering to bypass legislative restraints. He approved, for example, the transfer of several dozen new naval aircraft to France and Britain through a third party, based on the dubious claim that the planes were surplus and therefore exempt from statutory limits.¹⁸ Congressional reactions were mixed. Many members were coming to share Roosevelt’s sense of the gathering danger and the need to support Britain, though unease about stretching existing law persisted.¹⁹

Roosevelt doubled down on his aggressive legal interpretations when, in Spring and Summer 1940, Churchill urgently pleaded to him for over-age U.S. Navy destroyers. Germany had just blitzed through much of France and driven British forces from the European continent. A German knockout of Britain was now a real possibility, and Churchill’s government needed warships to guard the English Channel and protect British shipping. With the legal assistance of Attorney General Robert Jackson, Roosevelt traded fifty outdated destroyers for British military bases in the Western Hemisphere.

A tangle of statutes barred transferring warships to belligerent nations while the United States remained formally neutral. Some of the President’s advisers urged him to override those restrictions by asserting that his constitutional powers superseded them. Roosevelt, however, wanted to avoid provoking lawmakers. Instead, he turned to Attorney General Jackson, who concluded that Congress had implicitly permitted the President, in these circumstances, to waive certain limits on transfers. Jackson’s opinion also reflected the Executive Branch’s developing view of international law – one that, unlike the stricter reading embodied in the early Neutrality Acts, allowed neutral states to assist victims of aggression without forfeiting their neutral status.²⁰

Attorney General Jackson’s reading of the statutes is hard to square with their text and Congress’s intention to restrict transfers of military hardware to warring parties. But once the President committed to the destroyer deal, Jackson probably viewed this as the least-bad legal approach, thinking – correctly, it turned out – that once the trade was made, Congress would go along. To many observers, the episode reflected presidential unilateralism, but it also revealed a measure of legislative constraint. The deal was slowed while executive branch lawyers searched for a way to complete it that would least offend Congress’s stated preferences.²¹

The President, writes historian Tami Davis Biddle, “was pushing against Congress … but in taking these risks he was placing what he believed was the best long-term bet for U.S. defense – the survival of Britain as a combatant.”²² The pragmatic Roosevelt recognized that there were limits to claims of presidential power that Congress and the public would tolerate – especially after he in 1940 breached an unwritten norm by running for an unprecedented third term. On the one hand, Roosevelt’s moves to arm Britain (and France before its defeat) show that Congress’s power to dictate neutrality or war is limited by dependence on the Executive’s implementation of statutes. On the other hand, Roosevelt’s political advocacy for legislative changes and his administration’s efforts to justify actions as consistent with the law show that he understood the importance of keeping congressional support intact for any sustained campaign to aid allies.

It was also that summer that Congress enacted a first-ever peacetime national draft. Public opinion in favor of a draft ran high after the fall of France to Germany in June.²³ Constitutionally, though, this was remarkable. For much of American history, even a wartime national draft was constitutionally suspect. Chapter 6 explained that the World War I national draft was upheld by the Supreme Court as a necessity of a modern war. But in signing and invoking the 1940 Selective Service Act to build up the Army, Roosevelt stressed that, in light of threats from expansionistic empires and emergent transportation and military technology, the country could not wait for war to reach its shores: “America stands at the crossroads of its destiny. Time and distance have been shortened.”²⁴ Public and congressional opponents to a draft in 1940, meanwhile, cast it as a dangerous step toward both war and dictatorship – another reminder that American war-powers debates were historically driven by fears of domestic tyranny no less than foreign entanglements.²⁵

The 1940 act required men between the ages of twenty-one and thirty to register with their local draft boards, but contained important restrictions – both geographic and temporal – reflecting Congress’s continued hesitancy toward war. No more than 900,000 draftees could serve simultaneously, and no draftees could be sent outside the Western Hemisphere (with very narrow exceptions).²⁶ Here, again, Congress used its various Article I powers – this time its exclusive powers to create armed forces – to prepare for war while trying to avoid it.

The act’s limits, which were later lifted after the United States declared war, also reflected continuing jockeying between the President and lawmakers over where to set the lines of defense and how best to guard them. Roosevelt continued to urge that the protective perimeter be pushed far outwards, stressing that modern air and naval capabilities were narrowing the country’s oceanic buffer.²⁷ He and other internationalists believed that the United States could no longer wait until it was directly attacked before taking a military stand: “Our Bunker Hill of tomorrow may be several thousand miles from Boston.”²⁸ The President therefore wrestled the war-wary Congress to help keep a badly depleted Britain in the fight – and to prepare the United States to enter the war should the time come.

Among the most important steps in arming Britain was the March 1941 Lend-Lease Act. In his December 1940 fireside chat a few months earlier, the President had called for the United States to serve as the “arsenal of democracy.” “For us,” the President explained, “this is an emergency as serious as war itself.” Lend-Lease, which the Roosevelt Administration drafted and advocated to Congress, was a critical tool in meeting that emergency – and it passed by solid bipartisan majorities. The law repealed many of the Neutrality Acts’ restrictions, authorizing the President to produce or procure defense equipment for countries whose defense the President deemed vital to American security, and to sell, transfer, or lend them billions of dollars’ worth of that equipment.²⁹ The Act granted the President broad authority but preserved key limits meant to uphold U.S. neutrality, including bans on American ships entering combat zones and on naval convoying – restrictions the Commander in Chief later sidestepped as he directed the Navy, in gradual steps, to protect transatlantic supply routes and move the nation closer to open war.³⁰

Some critics called Lend-Lease an abdication of Congress’s power to declare war, arguing that practically it gave the President authority to commit the United States to ongoing conflicts. Political Scientist Edward Corwin wrote years later in his influential volume on the presidency that “[n]o more sweeping delegation of legislative power has ever been made to an American President,” as it was “to all intents and purposes … a qualified declaration of war” that allowed him to wage war by proxy.³¹ Among the leading anti-interventionist critics in Congress at the time was Republican Senator Robert A. Taft, who said the Act was “intended to give the President of the United States the right to carry on an undeclared war against Hitler through all the countries of the world that we can subsidize.”³² His Senate colleague Burton Wheeler charged that “[n]ever before has Congress coldly and flatly been asked to abdicate” such control over war and peace.³³ Hitler considered Lend-Lease tantamount to a war declaration, too. To its defenders in Congress, however, the Act was the United States’ best and last chance to aid Britain’s survival – and therefore hold the United States’ own distant-defensive line.

The critics and advocates of Lend-Lease both had a point. The program gave the President wide discretion to act in ways that might provoke attacks or put the United States on a path to war. Germany, for example, might view military support as violating prevailing international neutrality law. Even so, if war was coming anyway, Lend-Lease improved the odds that the United States would not have to fight it soon, alone, or close to home.

By December 1941, the period of almost-war was over. While the United States was edging toward a trans-Atlantic war, it was also imposing strict economic sanctions on Japan under a patchwork of statutory delegations and executive orders. Although designed to contain Japan’s expansionist aggression, those trade restrictions risked provoking war with the United States – and that is just what happened.³⁴ When Japan attacked Pearl Harbor and Germany joined in declaring war against the United States, Congress declared war for the fifth time in American history. In 1942, Congress would add war declarations against Germany’s allies Bulgaria, Hungary, and Romania. Those would be the last times the United States ever formally declared war.

The American preparation for and involvement in the war – short of direct participation – highlights a few key features of constitutional war powers. First, it shows how constitutional powers and checks beyond Article I’s Declare War Clause shape whether and when the United States makes war. The formal legislative war declaration process was not in any meaningful sense the locus of democratic deliberation. Once Japan attacked the United States, declaring war was a foregone conclusion. Congress’s debates and decisions about entering World War II occurred well before then. Even in analyzing declared wars, too much attention to the formalities of declaring or authorizing war obscures the ways in which other constitutional powers affect whether, when, and how the United States ultimately fights.

Second, this period of almost-war blurred the line between wartime and peacetime powers. The elected branches exercised a wide range of emergency powers before the United States directly entered the conflict. The Constitution’s text mentions “war,” “invasion,” “rebellion,” and “insurrection” – but it contains no general emergency power.³⁵ Perhaps the Framers thought those named scenarios covered the conceivable field, but now a new type of national defense crisis – one in which aggression still thousands of miles away endangered American security – no longer fit into those neat categories. A search for original constitutional meaning could not have provided much guidance for navigating this situation; constitutional practice had to stretch. As explained in the section below on economic controls, constitutional powers had also recently been reinterpreted in the interwar years to deal with another type of emergency, the Great Depression. Prior to Pearl Harbor and the U.S. declarations of war against the Axis powers, Congress and the President wielded newly enlarged powers to deal with a new sort of security crisis that was not war, but not peace either.

Third, as much as events in this period show the President’s strength in setting conditions short of war, they also illustrate some basic constraining features of the constitutional system. For all the built-in flexibility in its many substantive war powers, the Constitution also contains some rigid processes. Writing of this almost-war period from the later wartime vantage point of 1944, American government scholar Louis Koenig concluded: “The American President is handicapped” because, unlike European executives, he relies on statutory delegations in addition to constitutional powers to guide the nation through emergencies. On the one hand, the American President amid crisis is extremely powerful. On the other hand, he must rely “upon varied and scattered sources of authority,” and he is confined by the separation of powers – “The Supreme Court may dispute the interpretations he makes of his authority; Congress may withhold legislation which is an essential part of crisis powers.”³⁶

Koenig understated the power of the American presidency when occupied by someone as practiced and adroit as Roosevelt. Still, while uncertainty about the outer bounds of executive power may embolden presidents to press them further, the system remains thick with friction. A similar mix of executive initiative and interbranch friction would surface in the wartime economic mobilization that followed.

Presidential Command of the Wartime Economy

The United States was an economic giant but not a military one when it became embroiled in World War II. During the interwar years, the United States reverted to its longstanding aversion to a large standing army – throughout the 1930s, its regular Army was never larger than around 200,000 (smaller than Poland’s or Romania’s), whereas the active duty Army would peak at over eight million during the war.³⁷ When war clouds appeared, among America’s biggest strategic challenges was therefore time – time especially to convert its production of peacetime goods to production of wartime materiel, and then the ability to maintain efficient war production for an extended but unknowable duration. The United States had little trouble recruiting eager able-bodied volunteers and conscripts for a multi-million-man force, but there were limits to how quickly factories that produced cars and tractors could be retooled to produce tanks and bombers.³⁸ The complex U.S. economy could not become Roosevelt’s “great arsenal” to arm the Allies overnight.

Although World War II blurred public-private boundaries more than the previous war, ample constitutional precedent now existed for nationwide mobilization. Clinton Rossiter wrote in his classic 1948 treatise Constitutional Dictatorship about American governance in World War II that “[t]he mold of 1917–1918 was rarely broken; the grooves were simply cut a little deeper.”³⁹

Not only had World War I created the constitutional footing for total war on the home front – including broad wartime legislative authority and expansive delegations of policymaking discretion to the Executive – but the Great Depression had already reshaped peacetime constitutional law. Through the New Deal, which laid the foundation for the modern American welfare state, Roosevelt showed that powers comparable in breadth to those used in wartime could also be marshaled to confront economic crisis. In a 1934 case upholding a state mortgage-relief law, Chief Justice Charles Evans Hughes wrote for the Court that combating the Depression was akin to waging war and that legislative powers should be construed with similar flexibility needed to meet such an emergency.⁴⁰ As Corwin later observed, “the Constitution of peacetime and the Constitution of wartime ha[d] become, thanks to the New Deal, very much the same constitution.”⁴¹ The vast administrative machinery required to run a total-war economy still had to be built, but the constitutional blueprint for it was already in place.

The new constitutional move in World War II was bold claims that executive powers – not just legislative powers – could reach wartime economic emergencies. If modern warfare was an economic endeavor, was the next logical step that the President’s constitutional power extended beyond commanding military forces to commanding industries – or even labor and commodity markets – that sustained those forces? Roosevelt and his team thought so, but these assertions were not resolved or even thoroughly tested in World War II. Two examples involved price controls and production plants.

Inflation from swelling demand for goods and materials threatened the wartime economy. In early 1942, Congress therefore delegated to the Executive Branch emergency authority to establish and enforce price controls, subject to certain procedures. A few months later, the Roosevelt Administration grew frustrated that the price formulas dictated by Congress were insufficient to tame rising prices. So on Labor Day in 1942, the President threw down the gauntlet. He threatened that if Congress did not amend the statute by October 1, he would rework the statutorily required price control formulas himself:

Roosevelt continued: “When the war is won, the powers under which I act automatically revert to the people – to whom they belong.”⁴²

Roosevelt’s statement was vague as to the source or theory of that breathtaking assertion of power. It is unclear (probably deliberately so) whether he was actually claiming that he had constitutional power to violate and unilaterally rewrite law; that other emergency statutes implicitly supported the proposal; or that, as Jefferson and Lincoln had once argued, during certain exigent circumstances, it was appropriate for the President to act extra-constitutionally and seek legislative absolution after the fact.

It was certainly plausible that Roosevelt was audaciously claiming that in twentieth-century warfare, the entire domestic economy was its own battlefield in which the President commanded bureaucrats rather than soldiers. Roosevelt even likened executive intervention in the economy to repelling a sudden military attack on the nation.⁴³ Further, Roosevelt seemed to be claiming this supreme power for the duration of the conflict, whereupon it would revert not to the legislative branch he was overriding but to “the people.” Critics charged that this rhetoric was fascistic – the very ideology against which the United States was fighting.⁴⁴

Whether Roosevelt’s aggressive approach was necessary or prudent remains debatable. It captured the headlines, but his brazenness alienated allies on Capitol Hill and the press. Yet within a month, both chambers of Congress had conducted hearings; drafted, amended, and passed bills; and approved the conference report. The President signed a revised act just one day after his deadline.⁴⁵

The 1942 price control incident reflects how a president like Roosevelt can use his wartime platform to strong-arm Congress, including with vague constitutional claims. Still, Roosevelt pulled his punches. He resisted the advice of some confidants to act on his own, choosing instead to push Congress to do so. He also hinted obliquely that if he had acted without waiting for Congress, he would have done so based at least in part on some existing statutes, but he did not specify which ones.⁴⁶

The Executive’s bold legal arguments were clearer when it came to private factory and business takeovers by the government, though the outer boundaries of presidential power in that context were never settled. During the conflict, the U.S. government seized companies and plants during labor disputes dozens of times, usually involving firms producing war materials.⁴⁷ A notable incident even occurred in the almost-war period, when in 1941 – and with advice from then-Attorney General Robert Jackson – Roosevelt deployed the Army to seize the striking North American Aviation plant making military aircraft in California. Of all the World War II seizures, however, those involving Montgomery Ward & Company generated the most legal controversy. Though little remembered today, the episode underscores the breadth of total-war emergency powers Roosevelt claimed.

Montgomery Ward was a giant of American business, supplying much of the population with everyday goods – almost like Amazon of today. When the company’s workers went on strike in April 1944, Roosevelt ordered, “by virtue of the power and authority vested in [him] by the Constitution and laws of the United States,” that the Secretary of Commerce seize the company’s Chicago-based facilities and operate them “in any manner that he deems necessary for the successful prosecution of the war.”⁴⁸ Roosevelt surely relied on an opinion by Jackson’s successor, Attorney General Francis Biddle, who reasoned that Roosevelt could draw on authorities in the War Labor Disputes Act to seize Montgomery Ward’s facilities in order to avoid potential economic disruption. But Biddle also expressed a sweeping view of Article II presidential power in congressionally declared wars, writing, “In modern war the maintenance of a healthy, orderly, and stable civilian economy is essential to successful military effort.”⁴⁹ Whereas the 1941 North American Aviation strike had involved the direct production of weapons that Congress legislated for, now the Attorney General was asserting presidential power to maintain a healthy economy writ large.

Armed with the President’s seizure order and joined by nearly four dozen soldiers, top Commerce and Justice Department officials visited the company’s arch-capitalist chairman Sewell Avery at Montgomery Ward’s Chicago headquarters. When Avery flatly balked at the order, Attorney General Biddle directed soldiers to eject him from the building. An iconic image of Avery being carried off the property by two soldiers soon appeared on the front page of newspapers across the country.

The move proved unpopular among Americans who saw Avery as a victim of government overreach, and the government relinquished control of the company less than two weeks later, before any courts had the chance to weigh in.⁵⁰ Yet when another strike broke out at Montgomery Ward’s Detroit facilities in late December 1944, the Roosevelt Administration again seized its Chicago headquarters and commenced high-stakes litigation seeking a court judgment to support its move. An appeals court upheld the seizure as a valid exercise of the War Labor Relations Act’s enforcement authority. Without deciding on the scope of the President’s powers, the majority also nodded favorably at Biddle’s aggressive claim that the statute was unnecessary.⁵¹ The government likely would have won on the narrower statutory grounds had the issue ultimately reached the Supreme Court, but the war ended before it did and the Court dismissed the case as moot.

Throughout the war, the Executive Branch advanced broad claims of presidential authority in the context of total war. Courts did not resolve those claims definitively, and the President generally prevailed. Yet operating under legal uncertainty and amid a public wary of executive excess carried political costs. The Administration also had to work its way through legislative and judicial channels. If that legal and political friction tempered overreach in the economic sphere, it did far less in the civil-liberties arena.

The Dangers of Deference: Japanese Internment

On February 14, 1942, the military commander with responsibility for West Coast security, Lieutenant General John L. DeWitt, warned Secretary of War Henry Stimson that there were 112,000 potential enemy saboteurs waiting to strike in that critical zone of the home front. DeWitt was talking about Japanese immigrants and their Japanese–American children – all of them. He proceeded to explain that “the very fact that no sabotage has taken place to date is a disturbing and confirming indication that such action will be taken.”⁵²

The mass Japanese–American incarceration that followed is among the darkest episodes in the history of constitutional war powers. All three branches of government supported the profound injustice. It illustrates most poignantly courts’ wartime deference to military-necessity claims, the dangers of that deference, and a range of alternative approaches.

In February 1942, two months after Congress declared war against Japan, the President had signed an executive order stating that “the successful prosecution of the war requires every possible protection” against espionage and sabotage. Reeling from Japan’s surprise attack, the United States saw much of its Pacific fleet destroyed, its forces expelled from the Philippines, and Japan advancing across Southeast Asia. Some U.S. commanders and officials wrongly believed the Pearl Harbor attack was aided by Japanese spies, a view steeped in bigotry.⁵³

By virtue of his constitutional powers as chief executive and commander in chief, the President authorized the Secretary of War and designated military commanders to prescribe, among other restrictions, areas “from which any or all persons may be excluded.”⁵⁴ The Secretary of War tapped General DeWitt as head of the Western Defense Command. DeWitt declared large areas along the West Coast as exclusion zones, from which Japanese citizens and Japanese–Americans – more than 100,000 total – were to be excluded and relocated first to makeshift assembly centers and later to inland concentration camps. Weeks later, Congress made violating such orders a crime. Military leaders backed Japanese incarceration, but much political pressure came from federal and West Coast civilian officials.

In May 1942, Fred Korematsu, the son of Japanese parents who came to the United States, was arrested and prosecuted in his California hometown for violating General DeWitt’s exclusion order. Represented by the American Civil Liberties Union (ACLU), Korematsu challenged his ancestry-based exclusion as a denial of equal protection under the Fifth Amendment.

In December 1944, Supreme Court Justice Hugo Black wrote for a 6-3 majority in Korematsu v. United States that the forcible exclusion of Japanese–Americans was justified in light of security imperatives: “when, under conditions of modern warfare, our shores are threatened by hostile forces, the power to protect must be commensurate with the threatened danger.”⁵⁵ A year earlier, the Supreme Court had upheld a mandatory curfew for Japanese–Americans as within the government’s war powers.⁵⁶ Despite the much greater rights deprivation at issue now, Black viewed Korematsu as a natural extension of that precedent. He reasoned that courts should carefully scrutinize any government policy that discriminates based on race or ethnicity, but also that courts should defer to military leaders on questions of necessity. Black clearly prioritized the latter, consistent with courts’ general pattern of wartime deference when the political branches act in unison.

Justice Frank Murphy penned a biting dissent. While conceding wartime deference to military judgment, he condemned the orders as racist and ignorant – the sorts of attitudes “used in support of the abhorrent and despicable treatment of minority groups by the dictatorial tyrannies which this nation is now pledged to destroy.”⁵⁷ His dissent highlights a recurring dilemma. While the stakes, complexities, and responsibilities of war merit giving substantial weight to the judgments of those conducting it, the politics of war – shaped by public emotion and hasty decision-making – call for strong checks against error and abuse. Judges adjust their scrutiny based on how they prioritize those opposing risks.

While Justice Black’s majority opinion reflects judicial deference and Justice Murphy’s reflects moderate skepticism, Justice Jackson’s dissent charted a third path. Jackson, who had helped legally defend Roosevelt’s prewar policies before joining the Court in 1941, now judged them from a new vantage. Jackson regarded the race-based order as unconstitutional, but he agonized about courts’ capacity to check government overreach defended as militarily necessary. “[M]ilitary decisions are not susceptible of intelligent judicial appraisal,” wrote Jackson, so “courts can never have any real alternative to accepting the mere declaration of the authority that issued the order that it was reasonably necessary from a military viewpoint.” And yet, he continued, if the Court were to launder the constitutionality of the Executive’s racial discrimination, the precedent would then lie about “like a loaded weapon, ready for the hand of any authority that can bring forward a plausible claim of an urgent need.”⁵⁸ Better, in Jackson’s view, that courts stay out of the matter and the civilian and military leadership have to defend their deeds in the political arena.

Much as Jackson worried, the case illustrates courts’ tendency to defer heavily to the government in wartime clashes over constitutional rights, especially when – as here – the executive and legislative branches have acted jointly. And, yet, the takeaways about wartime judicial decision-making are not so clear-cut. Alongside Korematsu, the Court unanimously but narrowly struck down the detention of a Japanese–American whose loyalty the government conceded, holding only that statutes did not authorize detaining loyal citizens. By then, the Pacific war was also turning decidedly in American favor, and the government was about to dismantle the internment program anyway.⁵⁹

Germany surrendered in May 1945, and Japan surrendered that September, following the atomic bombings of Hiroshima and Nagasaki. Since then, Korematsu has stood less as precedent than a warning about the dangers of crisis decision-making and excessive judicial deference. In the early 1980s, a congressional commission determined that “each part of the [Korematsu] decision, questions of both factual review and legal principles, has been discredited or abandoned.”⁶⁰ Only in recent years did a Supreme Court majority formally repudiate the decision, remarking that it was “gravely wrong the day it was decided, [and] has been overruled in the court of history.”⁶¹

Ironically, the wartime injustice now associated with Korematsu unfolded just as the United States was helping design a new, rules-based international order to curb resort to war. But fitting that global ambition within the Constitution’s limits on war powers would soon expose its own tensions.

The United Nations and War Powers

Even before the Axis powers surrendered, the Allies were planning a new global body – what became the UN – aimed at preventing future wars. Among its most important provisions, the UN’s Founding treaty prohibited the use or threat of force by member states against others while preserving states’ inherent right of self-defense.⁶² The treaty also established a Security Council of representative states, with a mandate for maintaining peace and security and the power to employ military force. In the decade spanning 1935 to 1945, Congress went from legislating neutrality to supporting global security management.

The ambitious international legal framework revived war powers issues that had helped sink the League of Nations in the Senate back in 1919. To the Constitution’s Framers, a U.S.-led global collective security treaty organization would have been unimaginable. Some modern war powers questions were answered with interpretive innovations, some were quickly rendered obsolete, and others remain open today.⁶³

Unlike the League, in 1945 the UN Charter was approved overwhelmingly by the Senate, 89-2. That political context was surely important to working through associated constitutional issues. Throughout the negotiation process for the new global charter, the Roosevelt Administration coordinated with senators from both parties. Congress itself had advocated for such a project during the war, passing nonbinding resolutions by wide margins calling for a post-war collective security system.⁶⁴ Plus, all of this happened on the heels of a Great Depression and then a global war in which all three branches came to treat the Constitution as adaptable to modern crises.⁶⁵

The UN Charter’s architects regarded the Security Council’s ability to use military force as essential. The Council was to consist of five permanent members – the major victors of the recent war: the United States, Britain, France, the Soviet Union, and China – alongside a rotating group of states from around the world. It could impose economic or diplomatic sanctions against states that threatened or breached the peace, and if those measures were inadequate, employ military force. The UN would have no army of its own, relying instead on member states’ forces to carry out Council mandates. Now largely forgotten, Article 43 of the Charter called on all member states to make special agreements providing forces to the Council “in accordance with their respective constitutional processes.” Diplomats and officials in Washington and other capitals believed these agreements would furnish the ready military capacity the League of Nations had conspicuously lacked.

A basic dilemma, foreshadowed in the earlier League debates, was how to reconcile a nimble collective-security system with a Constitution deliberately built to slow – what some Framers called “clog” – the nation’s path to war.⁶⁶ The UN’s American architects knew its credibility required U.S. commitment to providing forces for joint interventions. Roosevelt argued that “[a] policeman would not be a very effective policeman if, when he saw a felon break into a house, he had to go to the Town Hall and call a town meeting to issue a warrant before the felon could be arrested.”⁶⁷ Roosevelt ally and Democratic Chairman of the Senate Foreign Relations Committee Tom Connally declared that “the Security Council must have both the power and the authority to act promptly in time of crisis, or it will fail in its all-important task.”⁶⁸ Meanwhile, and echoing objections from the League of Nations fight, congressional skeptics of the UN argued that the institution would weaken legislative prerogative by yielding power over war to the President – and even to foreign governments.

How, then, could the Security Council remain credible if Congress was to keep meaningful constitutional control over the nation’s decision to go to war? Policymakers in Washington devised two principal solutions to this dilemma, each bending or stretching the existing war-powers framework. One was to make American armed forces available to the UN Security Council. The other was to treat UN military interventions as “police actions” – something short of war. In either case, any deployment of U.S. forces still had to rest on presidential authority under the Constitution or on some exercise of Congress’s powers; no serious participant claimed that the UN Charter itself could supersede the Constitution.

First, a now-obscure provision of the 1945 UN Participation Act – the statute implementing the United States’ role in the UN – delegated limited authority to the President while retaining important legislative checks. To fulfill Article 43 of the UN Charter, it authorized the President to negotiate in advance “special agreements” with the Security Council for the use of American forces in multilateral security missions. Those agreements, however, needed congressional approval.⁶⁹ In effect, Congress would authorize presidential commitments to make designated U.S. forces available for Security Council use. Although regarded at the time as essential to the UN system’s credibility, this provision of the Participation Act was never implemented. No state has ever concluded an Article 43 agreement with the UN; Cold War rivalries made such pledges unrealistic, and that reality survived even the Soviet Union’s collapse.

To reconcile the Charter’s collective-security arrangements with the Constitution’s division of war powers, leaders in both branches also advanced a second – and ultimately more durable – approach: classifying certain military operations as “police actions,” distinct from interstate war and therefore not requiring congressional assent. One lesson political leaders drew from World War II was that early, limited military measures might prevent larger conflicts. If used to head off major war, the reasoning went, a smaller-scale multilateral intervention need not trigger the Constitution’s Declare War Clause.⁷⁰ The influential Republican Senator Arthur Vandenberg, who abandoned non-interventionism after Pearl Harbor, now took the view that “for 150 years the President has had the right to use our armed forces in a preliminary way for the national defense and in the interest of preventing war. That is a complete analogy to the intended use of preliminary force by the Security Council.”⁷¹ For the Executive Branch, the concept of “police actions” provided a label for its longstanding practice of employing modest force to address limited breaches of the peace.

Meanwhile, international law was evolving in ways that reinforced this distinction between war and armed conflict short of war. World War II was the last time Congress formally declared war, and the practice of war declarations abroad declined sharply thereafter. The UN Charter’s restriction of force to self-defense or Security Council authorization contributed to that shift. Beyond questions of doctrine, the widening public view of war as a moral catastrophe also made traditional declarations seem outdated.⁷² Later chapters address Congress’s modern alternative of authorizing force, but as formal declarations disappeared, the constitutional boundaries around “war” – and thus the power to make it – blurred even further.

The idea of placing standing U.S. forces at the Security Council’s disposal did not survive the onset of the Cold War. The constitutional arguments supporting a presidential power to undertake limited military operations abroad, however – even if not labeled as “police actions” – endured. They would prove crucial in the decades that followed.

Conclusion

Through the interwar years until December 1941, both elected branches exercised a range of constitutional powers – not the declare-war power – that shaped whether, when, and how the United States ultimately entered the conflict. Congress had multiple tools for steering the nation away from foreign entanglements, but its influence was limited by a President determined to confront fascist aggression before it reached American shores or even the Western Hemisphere. The President, for his part, had tools short of direct military action that allowed him to prepare for, and ultimately move toward, a war he regarded as inevitable. Yet his freedom of action was constrained – at different moments and to varying degrees – by Congress.

World War II itself did not create major new templates for war powers. It mostly amplified precedents from World War I and the New Deal, as established constitutional formulas – such as broad wartime legislative authority and sweeping delegations of regulatory discretion to the Executive Branch – were pushed to new levels to support warfare on an unprecedented scale. Rather, World War II’s most far-reaching implications for constitutional war powers emerged from the transformation in American grand strategy that followed.

Earlier chapters showed that throughout the nineteenth and into the early twentieth centuries, the United States asserted its influence beyond its borders – most prominently along its immediate frontiers but increasingly across the Western Hemisphere. Government actors now debated how far that military presence or influence needed to reach to ensure American security.

The attack on Pearl Harbor shattered long-standing strategic assumptions – dating to the Founding – about geography serving as America’s shield.⁷³ By the end of World War II, advances in maritime transport, aviation, and soon ballistic missiles had collapsed the distances that once buffered the United States from distant threats. After victory, the nation could no longer retreat from global commitments as it had after World War I.

The chapters that follow trace how the constitutional system would adapt to a grand strategy of deep entanglement and sustained mobilization – and how that strategy, in return, would remake American war-powers law and practice.