The separation of powers, a concept foundational to our democracy, is crumbling. The Framers sought to create a national government free from tyranny. Believing the accumulation of all powers in the same hands to be the very definition of tyranny, they deliberately limited presidential authority. The drafters of our constitution were particularly concerned with the powers governing war, and they wanted to ensure that the authority to declare war and to raise and support armies, as well as other war powers, did not lie with a single individual. James Madison wrote, “The constitution supposes, what the History of all Governments demonstrates, that the Executive is the branch of power most interested in war, and most prone to it.” The Framers therefore placed the power to declare war with Congress and designated the President as “Commander in Chief of the Army and Navy,” giving the office the power to conduct duly authorized war. They recognized that the deliberative nature of the legislative process and the representative nature of Congress would protect the nation from unilateral executive war-making.

However, our system of checks and balances has not functioned as intended. Since the mid-twentieth century, presidential administrations of both parties have arrogated increasing unilateral power to the executive branch. Compounding this problem is Congress, which has largely failed to intervene. In the wake of the Vietnam War and the Watergate scandal, several laws were passed to reassert congressional prerogatives with respect to matters of war and peace. But through a combination of judicial decisions, executive branch interpretation, and congressional acquiescence, these frameworks have been rendered increasingly ineffective. The result has been decades of unaccountable U.S. involvement in conflicts that have claimed thousands of lives and dramatically increased defense spending, as well as the pace of arms sales to other nations. As the United States positions itself in this new era of global politics and challenges, recent history offers a reminder of why reasserting the proper role of Congress is essential to getting national security policy right.

This encroachment did not happen overnight. Presidents of both parties and members of Congress have created the space and political cover for the repeated abuse of authority by the executive branch, and the subsequent erosion of the separation of powers. Further compounding this problem is the inconsistency with which those in power uphold their own principles and values.

History demonstrates that those who wish to go to war will find a way to do so. They often insist that congressional authorization is unnecessary, no matter how staunchly they might have previously defended the constitutional separation of powers. The reverse is also true: Those who oppose a war might suddenly find themselves strongly advocating that Congress must intervene. Indeed, those with the power to decide whether this nation goes to war have too often interpreted the Constitution so as to leave the decision largely in their own hands.

This attitude was brought home starkly to one of the authors of this article, Morton Halperin, in 1993, when he was serving as a special assistant to Secretary of Defense Les Aspin. President Bill Clinton had placed the issue of war powers and what approach his Administration should take on the agenda for a meeting of the National Security Council. While preparing Aspin for the meeting, Halperin came across an article on war powers written by then-Secretary of State Warren Christopher when he was in private law practice after having served as deputy secretary of state during the Carter Administration. The article proposed that at the start of a new administration, the President and Congress should draw up a compact spelling out the role of each branch on decisions relating to war and peace. Christopher suggested that “the forum for confirming such undertakings could be a meeting between a broad range of congressional leaders and the President and key national security officials.”

Halperin showed the article to Aspin and suggested that he propose the Administration announce its willingness to negotiate a new compact and start the process by having President Clinton host a meeting with congressional leaders. Aspin liked the substance of the proposal and the idea of his suggesting that the Administration implement a proposal made by the secretary of state. He committed to bringing it up at the next National Security Council meeting called to discuss war powers. Aspin reported later that when he raised the idea, giving full credit to the secretary of state, Christopher made it clear that he would not support it, explaining that he was only in favor of such an approach when there was a Republican President.

This dynamic has played out time and time again, in particular since the mid-twentieth century and the start of the Korean War. Upon learning that North Korea had attacked South Korea in late June 1950, President Harry Truman first ordered that only supplies be sent to South Korea, with air and naval support soon to follow. At the same time, the UN Security Council approved a resolution calling for a cessation of hostilities and for North Korea to withdraw its forces. The council then requested military assistance from UN members, but Truman had already ordered U.S. air and sea forces to assist South Korea.

Though some members of Congress agreed with Truman’s action, Senator Robert Taft of Ohio went so far as to claim that the President had usurped power and violated the Constitution. Later, when Truman ordered ground troops to the Korean Peninsula, more members grumbled their protest, arguing that the action required congressional debate and approval. Truman countered that he “had to act as commander-in-chief.” He also claimed legal authorization from the United Nations, an assertion with little to support it, given that Truman had committed forces prior to the UN request and that the approval of the UN Security Council could not supersede the requirements of the Constitution. Despite lawmakers’ concerns with President Truman’s unilateral war-making, Congress did nothing to check him. Indeed, Congress regularly authorized and appropriated funds to support the war. This acquiescence set a dangerous precedent that would be used as justification for similar actions by future presidents in the decades to come.

Just a few years later, Congress opened the door even further to expansive executive power. Following confrontations in the Gulf of Tonkin off the coast of North Vietnam, and at the request of President Lyndon Johnson, Congress passed the Tonkin Gulf Resolution of 1964. The resolution would approve the “determination of the President, as Commander in Chief, to take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression.” As Congress considered the measure, some members questioned whether the use of force authorized by the resolution would amount to a war—one that would not have received the necessary congressional authorization. The answer to their question was yes. As Senator J. William Fulbright, who had been tasked by the Johnson Administration with shepherding the resolution through Congress, explained: “We all hope and believe that the president will not use this discretion arbitrarily or irresponsibly…. The policy of our government not to expand the war still holds.” But expand the war is exactly what President Johnson would do, treating the resolution as a declaration of war and committing several hundred thousand troops to South Vietnam.

The number of American casualties in the Vietnam War grew steadily over the years, while public support declined. Secret bombing campaigns conducted in Laos and then in Cambodia, eventually followed by the unauthorized deployment of ground troops to Cambodia, spurred Congress to act. Congress rescinded the Gulf of Tonkin Resolution in 1971 as part of a $200 million bill authorizing credit sales of U.S. arms to foreign allies. President Nixon was unbothered by the inclusion of the repeal and agreed to sign the bill, claiming that the only authority he needed to fight in Southeast Asia was his authority as commander-in-chief. Congress disagreed, and two years later introduced and passed the War Powers Resolution of 1973, overriding President Nixon’s veto.

The committee report for the resolution stated: “We live in an age of undeclared war, which has meant Presidential war…. Prolonged engagement in undeclared, Presidential war has created a most dangerous imbalance in our Constitutional system of checks and balances.” The law contained many safeguards to rein in executive powers and protect against future abuses. It requires that any introduction of U.S. forces into hostilities, or into situations where “imminent involvement in hostilities is clearly indicated by the circumstances,” must be terminated within 60 calendar days unless the action is expressly authorized by Congress. The War Powers Resolution, along with the Arms Export Control Act and the National Emergencies Act—also enacted in the 1970s to provide stricter oversight over certain presidential actions—represent perhaps Congress’s most meaningful attempts to reclaim its power. But as articles in this symposium will explore, the War Powers Resolution has mostly failed to adequately restrain unilateral military action by the President.

Over the decades, presidents of both parties have tested the limits of the War Powers Resolution and further encroached on Congress’s power. From President Jimmy Carter’s unsuccessful attempt to rescue American hostages in Iran in 1980, to military exercises conducted in Honduras under the orders of President Ronald Reagan in 1983, to the thousands of U.S. troops ordered to Panama in 1989 by President George H. W. Bush, presidents found ways to circumvent the requirements of the War Powers Resolution. Each of these events enabled the executive branch to arrogate more power to itself by narrowing the scope of military activity that would require congressional authorization. The ability of Congress to intervene was further complicated by the 1983 Supreme Court decision in INS v. Chadha, which held that the kind of “legislative veto” enabled by the War Powers Resolution—legislation passed by simple majorities in both houses of Congress that nullified an executive action, without the President’s signature—was an unconstitutional violation of the separation of powers.

A significant test of the War Powers Resolution came after Iraqi troops, under the direction of President Saddam Hussein, invaded Kuwait in August 1990. Together with the United Nations, the elder President Bush worked swiftly to obtain international support and authorization for military action against Iraq. This raised the new issue of whether, under the War Powers Resolution, a President could commit U.S. troops to support a UN Security Council resolution without congressional authorization. This issue would ultimately not be resolved, as Bush reported to Congress just a week after the invasion that he had already deployed U.S. forces to the region to deter Iraqi aggression. His decision, he argued, was consistent with the War Powers Resolution, as he did not believe involvement in hostilities to be imminent.

At the same time, New York Democratic Congressman Stephen Solarz organized a bipartisan group of stakeholders to generate support for President Bush’s Gulf policy. Among those included in that group was Morton Halperin, then serving as the Washington office director for the American Civil Liberties Union. This group would go on to place several full-page advertisements in major newspapers advocating for U.S. military intervention in the Gulf. When Halperin was asked to endorse these advertisements, he agreed to do so under the condition that they included the line “if Congress approves.” The line was not added, and so Halperin did not endorse the effort. He was not the only one to insist on congressional authorization. Indeed, some lawmakers sought a judicial order enjoining the President from offensive military operations unless he obtained authorization from Congress. But a few months later, after hundreds of thousands of U.S. troops had already been deployed and the prospects of a war without congressional approval had become increasingly likely, Congress passed the “Authorization for Use of Military Force Against Iraq Resolution” in January 1991. The U.S. ground invasion commenced shortly thereafter. And this resolution unfortunately remains active to this day.

One of the major flaws of the War Powers Resolution would be revealed decades later, following the 9/11 terrorist attacks. There was, of course, a broad consensus that military action needed to be taken against the entity that carried out the attacks—quickly identified as Al Qaeda—and those who supported it. However, it was not clear what the full scope of the authorization for the use of military force (AUMF) should be, as the War Powers Resolution did not provide any kind of framework or guidance. Seeking to seize the moment to get broad authority, the Bush Administration asked Congress to enact this text:

That the President is authorized to use all necessary and appropriate force against those nations, organizations or persons he determines planned, authorized, harbored, committed, or aided in the planning or commission of the attacks against the United States that occurred on September 11, 2001, and to deter and pre-empt any future acts of terrorism or aggression against the United States.

The portion of that draft giving the President the authority “to deter and pre-empt any future acts of terrorism or aggression against the United States” was a main cause of contention between the White House and Congress. This language would theoretically expand the President’s authority to use force beyond the scope of the 9/11 attacks, representing a blanket authorization for military operations that could be relied on well into the future.

The Senate, with then-Chair of the Foreign Relations Committee Joe Biden playing a prominent role, pushed back. Senate Majority Leader Tom Daschle introduced alternative language that would give the President the power to use force only “in order to prevent any future acts of international terrorism” by people, groups, or nations connected to the 9/11 attacks. This alteration—replacing “and to deter and pre-empt” with “in order to prevent”—made it clear that the prevention of future attacks was a justification for the authorities being given to the President, not an additional authorization. After some back and forth, the Senate language was adopted with near unanimity. In remarks on the Senate floor on September 14, 2001, Biden noted that Congress gave the President the power to wage war on those who perpetrated the attacks “without yielding our constitutional right to retain the judgment in the future as to whether or not force could, should, or would be used.”

Yet the Bush Administration interpreted the authority granted to it by Congress more along the lines of the original language. It became clear that the Administration believed it had the authority to take this war on terror beyond Al Qaeda and those who “harbored” them—that is, the Taliban. Relying on the example of World War II—during which the United States was at war with not only Germany, Italy, and Japan, but also their co-belligerents Hungary, Bulgaria, and Romania—both the Bush and Obama Administrations claimed that certain “associated forces” of Al Qaeda were also covered by the 2001 AUMF. This led to military action against terrorist groups such as an Al Qaeda affiliate operating in Yemen under the name Al Qaeda in the Arabian Peninsula, which could at least be legitimately described as an associated force of Al Qaeda. But the reliance on associated forces was also used to target groups that could not reasonably be considered co-belligerents of Al Qaeda, such as the Islamic State of Iraq and the Levant (ISIL), a terrorist group that was in direct military conflict with Al Qaeda and Al Qaeda affiliates in Syria and Iraq.

An additional area of concern was the lack of transparency regarding which terrorist organizations the executive branch had determined were included under the 2001 AUMF. Unlike in the case of the co-belligerents in World War II, who were fighting openly alongside the Axis powers, Congress was largely in the dark about which terrorist groups had been deemed associated forces. In a May 2013 hearing of the Senate Committee on Armed Services, the chairman, Michigan Democrat Carl Levin, was reduced to asking whether the Department of Defense officials testifying could provide him with a list of such groups.

U.S. military operations in Libya under President Barack Obama would later underscore just how expansive the criteria under which a President could claim unilateral power to act had become. While President Obama may not have formally described the War Powers Resolution as unconstitutional, his Administration found creative ways to interpret its restrictions that rendered it functionally meaningless. In March 2011, Obama ordered U.S. military action to support an international coalition coming to the defense of civilians threatened with slaughter by the forces of Libyan strongman Muammar Gaddafi. There was no congressional authorization to support this action. Over the following weeks and months, that mission expanded to include enforcing a no-fly zone, and it ultimately drove Gaddafi from power.

By June 2011, the 60-day time limit included in the War Powers Resolution, after which a President must withdraw forces from hostilities if that military action is not authorized by Congress, had expired, but U.S. forces remained engaged in Libya. Rather than removing them, the Obama Administration sent a legal analysis to Congress asserting that the type of military action undertaken—air and drone strikes, and other actions to protect civilians and enforce a no-fly zone and arms embargo—did not constitute hostilities as defined by the War Powers Resolution and therefore were not subject to the 60-day time limit. Although Obama would have welcomed congressional support for the Libyan air war, he believed he had the constitutional authority to conduct it without explicit authorization.

The presidency of Donald Trump produced numerous other examples of how the executive branch had usurped the constitutional role of Congress. President Trump vetoed two separate war powers resolutions, the first that Congress had ever actually passed in an effort to end military engagements. In April 2019, Trump vetoed a resolution aimed at ending U.S. involvement in the Saudi-led war in Yemen. And in May 2020, he vetoed a second that was focused on preventing U.S. military action against Iran without congressional approval. Congress failed to override both vetoes.

President Trump would go on to veto multiple attempts by Congress to check his actions, including three bills in 2019 aimed at halting more than $8 billion in arms sales to Saudi Arabia and the United Arab Emirates. This series of vetoes highlighted a dangerous truth: Arms transfers can be pushed through the approval process by a President even when there is overwhelming congressional opposition. To date, Congress has never successfully prevented a notified arms transfer through legislation.

Trump brought the threat of a truly imperial presidency into even starker relief when he declared a national emergency on the U.S.-Mexico border in order to divert billions of dollars from military construction projects to build sections of a border wall. This declaration was seen by many as an attempt to go outside the bounds of the constitutional legislative process and a clear abuse of executive authority. Trump countered that the “flow of drugs, criminals, and illegal immigrants from Mexico constituted a profound threat to national security that justified unilateral action.” Congress tried to check the President by introducing and passing two separate resolutions to overturn the national emergency declaration. Trump vetoed both resolutions, the first in March 2019 and the second in October 2019. Congress once again failed to override the vetoes.

The concentration of national security powers in the presidency is a problem that stretches back decades and implicates both parties. All Americans have a stake in decisions to go to war, to bypass ordinary laws through emergency declarations, or to sell weapons to foreign regimes. That is why our constitutional system of checks and balances calls for the judgment of both Congress and the President on these vital questions. But today, Congress does not have the tools it needs to adequately restrain the President. The underlying frameworks governing the actions at issue—the War Powers Resolution, Arms Export Control Act, and National Emergencies Act—all permit Congress to intervene with a simple majority vote from each chamber. However, due to the Supreme Court’s decision in INS v. Chadha, the President can veto such a resolution, necessitating a veto-proof majority to terminate unilateral executive actions.

A system where Congress, the “people’s branch” of government, cannot check the actions of the President is not democracy. But despite recent decades, there is much that Congress can do to reassert its power and restore balance. Progress on this front will require broad consensus across the branches of our government and across political parties—a daunting task when we consider how easily a person’s position on the matter can shift depending on what role they hold. As a senator, Joe Biden was deeply committed to enforcing the terms of the War Powers Resolution and tried on several occasions to clarify and strengthen parts of it, especially in the wake of INS v. Chadha. Following Donald Trump’s veto of the war powers resolution on Iran in May 2020, candidate Biden released a statement criticizing the veto as another demonstration of Trump’s contempt for Congress as a coequal branch of government:

The war power is shared under our Constitution, for a simple but profound reason: the Framers understood that the solemn decision to take the country to war requires the informed consent of the American people, as expressed through their elected representatives and their President. When I am President, I will work closely with Congress on decisions to use force, not dismiss congressional legislation as “very insulting.”

Now, as President, Biden has taken a decidedly different position. In response to a recent New York Times survey of presidential candidates on executive power, President Biden stated that he has the authority “to direct limited U.S. military operations abroad” without congressional approval when such strikes serve critical American interests.

This symposium will explore that tension between Congress and the executive branch, along with some potential remedies that could recalibrate the balance of power. In order to prevent future abuses of these powers, particularly the use of force, emergency declarations, and arms transfers, Congress could amend the respective statutory frameworks to require that the President seek affirmative authorization from Congress before acting. There are of course instances, in genuine emergency situations, when the President may proceed without congressional approval, but only for a limited period of time. Congress must also ensure that these national security powers are used for clearly defined purposes—with their use subject to regular review by Congress—and only as a last resort.

Of course, the dangers of the imperial presidency permeate much more than just the issues discussed in this article. We’ve chosen to focus on war powers, national emergencies, and arms transfers as a way to highlight the history and nature of this evolving threat, in addition to how it might be remedied. But the erosion of the separation of powers and the resulting inability, or in some cases unwillingness, of Congress to intervene jeopardizes more than just our policy process. At this pivotal moment in history, as the world grapples with evolving global challenges, the restoration of Congress’s role and voice is not just a matter of national security. It is a matter of safeguarding our democracy.