President Donald Trump’s recent authorization of the use of “bunker-buster” bombs against Iranian nuclear facilities has touched off a debate over the war-making power of the presidents. Democratic Senator Tammy Duckworth of Illinois has denounced the action as illegal and unjustified, a view shared by many Democrats. Republican members of Congress, meanwhile, have mostly applauded the action (Representative Thomas Massie of Kentucky being a notable exception).
What to make of this?
The war power is arguably the best example of checks and balances in our system of government. Under the Constitution, Congress has the exclusive power to declare war.
The president can ask for war, historically referred to as a “war message,” but the final decision rests with Congress.
Additionally, Congress has the exclusive power to fund the war, and the Constitution limits appropriations for the army to two years. Finally, Congress has the final authority to accept the terms of peace — all treaties require a two-thirds vote in the Senate before they take the force of law. But when war has been declared, authority over the armed forces belongs exclusively to the president, whom the Constitution names the “commander in chief.” Moreover, it is the job of the president to negotiate peace with foreign leaders.
The idea here is that the president, as a unitary official commanding the executive, possesses the capacity for what Alexander Hamilton in Federalist 70 called, “decision, activity, secrecy, and dispatch.” He can act quickly to seize the initiative, and thus is invested with the powers that require such capacity. Congress, as a deliberative body, cannot handle such duties; but, as the representatives of the people, it is tasked with determining whether a conflict is in the public interest.
While the Constitution creates a general framework for questions of war and peace, it does not have an answer for every possible situation. There have been many instances over the years when the precise distribution of these powers has created tension between the branches. In 1793, for instance, Great Britain declared war on the French Republic. George Washington’s Administration had to consider whether the United States was obligated, under the 1778 Franco-American alliance, to join the war on behalf of the French. Ideally, congressional input would have been appropriate, but Congress was out of session and time was of the essence. So, the Washington Administration made the unilateral decision to declare that it was not taking sides. This “Neutrality Proclamation,” as it became known, was met with controversy in its day, with James Madison warning (under the pseudonym Helvidius) that, taken too far, this could undermine the constitutional system of checks and balances.
Even when Congress has formally declared war, the lines of authority can be blurry. For instance, in 1846 Congress declared war on the Republic of Mexico for attacking and killing American soldiers north of the Rio Grande River, on territory claimed by the United States. But President James K. Polk only moved American soldiers into the territory, which Mexico also claimed, after negotiations to purchase California had broken down. The ensuing war produced the Treaty of Guadalupe Hidalgo, in which Mexico finally sold California to the United States. Moreover, after the Civil War, there were constitutional questions about who should helm Reconstruction — the president as part of his power to put down insurrections, or Congress as part of its power to admit states into the Union.
These ambiguities became a more frequent source of tension after World War II, when the United States took on the burdens of a global superpower. Harry Truman took the United States into the Korean War of 1950-53 without congressional approval, instead justifying it as a police action under the auspices of the United Nations. Likewise, the military buildup in South Vietnam prior to 1964 did not have explicit congressional authorization. Congress only formally sanctioned military action with the Gulf of Tonkin Resolution of 1964, which gave the president the authority “to take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression.” Yet even with this broad grant of power, the president pushed further — with Richard Nixon beginning a secret bombing campaign against Cambodia in 1969.
Growing opposition to the Vietnam War combined with the sense that the president had gone beyond his constitutional authorities led to the War Powers Resolution of 1973, passed over President Nixon’s veto. The War Powers Resolution, which remains in effect today, requires the president “in every possible instance” to “consult with Congress” before introducing forces “where imminent involvement in hostilities is clearly indicated by the circumstances.” Within 48 hours of committing forces, the president must report the deployment to Congress. The president then has 60 days to carry on his efforts without a formal declaration of war or congressional resolution of support. Congress can respond by declaring war, passing a resolution of support or vetoing the action, or doing nothing. If Congress does nothing, the president must remove forces after 60 days.
The purpose of the War Powers Resolution was to update the original constitutional vision of shared power for the modern age, when it is often impractical to receive congressional approval before engaging American forces. But its record has been mixed. For starters, there are constitutional questions — particularly the issue of a congressional veto requiring the removal of armed forces. Though the Court has never considered the issue directly as it relates to the War Powers Resolution, in INS v. Chadha (1983) it ruled a similar device in the Immigration and Nationality Act unconstitutional.
Moreover, the executive branch has often seen it as an incursion into its constitutional authority, and thus has been loath to accept it. President Nixon vetoed it in part on constitutional grounds, arguing that an automatic cutoff of authority after 60 days was illegal under the Constitution, and that concurrent resolutions cannot have the force of law because they are enacted without presidential approval. Subsequent presidents have endeavored to avoid the provisions of the War Powers Resolution, interpreting it to generate maximum freedom for their actions.
There have been nearly 200 reports to Congress submitted under the War Powers Resolution, but only one was submitted in a way that would trigger the 60-day withdrawal countdown. For example, President George H.W. Bush ordered soldiers to Panama in December 1989; he notified Congress of the deployment but was careful not to do so in a way that would trigger the 60-day timeline.
And in dozens of instances over the years, the president has acted without giving Congress notice under the War Powers Resolution. For instance, in 1998 President Bill Clinton initiated Operation Desert Fox, a 1998 bombing campaign against Iraq without following the protocols of the War Powers Resolution.
Since the attacks of 9/11, the power of the president to initiate military conflict without additional congressional approval has expanded. The 2001 Authorization for the Use of Military Force (AUMF) gave the president the power “to use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons.” Originally intended to authorize the attack on Afghanistan, the language is extremely broad, and presidents have used the AUMF to justify attacks not only in Afghanistan, but also Yemen, Ethiopia, Somalia, the Philippines, and more.
Though Congress has struggled to find a legislative framework to limit presidential action, it has usually refused to use the constitutional provision that it still possesses — the power of the purse. Military appropriations must be regularly reauthorized under the Constitution. Congress has done that time and again since the end of the Vietnam War, and has only rarely used its power to restrict presidential activity.
If Congress could still restrain presidential war-making, why does it refuse to do so? Perhaps the answer is that the public itself provides the check on the executive branch. When the president has initiated military action over the last 40 years, he can either count on public support or, at the least, public indifference. Indeed, instances of congressional involvement — like Vietnam starting in 1970, Nicaragua in 1984, Somalia in 1993, and Rwanda in 1994 — were for executive actions in which there was a measure of controversy over the purpose or scope of the mission. Congress, from this perspective, is actually following public opinion in deferring to the president most of the time.
Perhaps today’s tension between the president and the Congress over the war-making power is not so different as it was in 1793. Did President Washington have the authority under the Constitution to declare the policy of the United States as “friendly and impartial toward the belligerent powers?” Theoretically, the argument could go either way. But as a practical matter, the president had the backing of the American people in making the declaration, and that was effectively that. That remains the case to this day — the constitutional tension between the president and Congress over the war-making power plays out in a broader republican context in which the people have the final say. If they do not like an action the president has taken, they will no doubt embolden Congress to act.
Jay Cost is the Gerald R. Ford Senior Nonresident Fellow at the American Enterprise Institute. He is the author of five books, most recently Democracy or Republic? The People and the Constitution (AEI Press, 2023).
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