Whether the US President has the power to declare war is a matter of US constitutional law. That question can be answered theoretically, politically, or historically. Whatever it is, everything depends on the year 1964. And the story told by the events of that year and the decades that followed is the story of the slow erosion of Congress’s power.
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On August 2, 1964, North Vietnamese torpedo boats attacked the USS Maddox in the Gulf of Tonkin. Following highly disputed reports of the second attack, President Lyndon B. Johnson ordered the bombing and asked Congress to pass a joint resolution of support. Johnson had been looking for such a proposal since the last weeks of 1963 and began discussing it in earnest the following February. Johnson adviser Jack Valenti later said, “Coming from a Congressional lineage, he was very dissatisfied and dissatisfied with the fact that we were messing around in Southeast Asia without congressional approval.” As a senator, Johnson particularly objected to Harry Truman sending troops to Korea without seeking support from Congress. Valenti said, “If any president had tried to get away with this when Johnson was majority leader in the Senate, Lyndon Johnson would have torn his balls off.”
Whether the US President has the power to declare war is a matter of US constitutional law. That question can be answered theoretically, politically, or historically. Whatever it is, everything depends on the year 1964.
Pressed by Johnson to support the administration’s actions in Vietnam, Senator J. William Fulbright, chairman of the Senate Foreign Relations Committee, began working to harass his colleagues immediately after the attack on Maddox. On the Senate floor, he assured that the measure was overly narrow, but it was also clear that at least some members of the Senate understood the breadth of the proposal.
Mister. BREWSTER: My question is whether there is anything in the resolution that would authorize or recommend or approve the landing of large American forces in Vietnam or China.
Mister. Fulbright: As I read, there’s nothing in the proposal that contemplates this. I agree with the Senator that this is the last thing we would want to do. However, the language of the proposal would not prevent this. It will authorize whatever the Commander-in-Chief deems necessary.
On August 7, Congress issued a joint resolution declaring its support for “the determination of the President, as Commander in Chief, to prevent any armed attack against the forces of the United States and to take all necessary measures to prevent any further aggression.” Johnson was pleased, commenting that the Tonkin Gulf Resolution, “like Grandma’s nightshirt… covers everything.”
Fulbright regretted both the vote and the war whose conduct he had authorized. In 1967, he chaired a hearing investigating US military operations in Vietnam. Johnson, angry at what he considered a betrayal, said, “Do you know when you’re milking a cow and you’ve got all the frothy white milk in the bucket and you’re just about to drink the milk, when all of a sudden the cow turns her tail through the manure pile and slams into that frothy white milk? That’s Bill Fulbright.” In 1971, tired of the war in Vietnam, Congress repealed the Tonkin Gulf resolution. Two years later, Congress, determined to prevent “another Vietnam”, jointly passed the War Powers Resolution; That measure was intended to give the legislature its exclusive constitutional power to declare war, limiting the circumstances under which the President could do so to “a national emergency arising from an attack on the United States, its territories or possessions, or its armed forces.”
In 1964, the House voted unanimously in favor of the Tonkin Gulf resolution, and only two senators voted against it: Ernest Gruening, a Democrat and former governor of Alaska, and Wayne L. Morse, a Democrat from Oregon and former dean of the University of Oregon Law School. Gruening, who trained as a doctor, spent his early career as a foreign-policy journalist, and was an editor Nation. His position regarding American involvement in Vietnam is linked to his opposition to the American occupation of Haiti.
Gruening, a so-called peace progressive, anti-imperialist, pro-democracy of the Wilsonian era, had objected to American involvement in foreign wars since the 1920s. Elected to the Senate in 1958, he consistently warned against U.S. entry into the war in Vietnam, questioned American intelligence, and in March 1964 called it an “impossible war.” During the debate on the Tonkin Gulf resolution, Gruening said, “The charge that we are supporting independence in South Vietnam rings hollow.”
Morse’s disagreement is a more interesting case. Morse, a progressive Republican from Wisconsin and an avid Cold Warrior, was elected to the Senate from Oregon, but his failure to censure Joseph McCarthy led him to leave the Republican Party and become a Democrat in 1955. In 1957, he unsuccessfully objected to a resolution introduced in Congress by Dwight Eisenhower that sought pre-authorization for military action in the Middle East, calling it “constitutionally dangerous.” After the Bay of Pigs fiasco in 1962, Morse predicted that “We are in a situation in which we will probably never again see Congress pass a declaration of war before the start of the war.” History proved him right.
Morse protested against unauthorized military action so often, and spoke so many times, at the end of the day, in front of an empty chamber, that he earned the nickname the Five O’Clock Shadow. In 1963, John F. A week before Kennedy’s assassination, Kennedy privately confided to Morse, “Wayne, I want you to know that you are absolutely right in your criticism of my Vietnam policy.” In the spring, when Johnson sought military appropriations, Morse accused him of “attempting to indirectly obtain congressional approval for our illegal, unilateral military action in South Vietnam without coming forward with a request for a declaration of war.”
In August, Morse objected to the Tonkin Gulf resolution on constitutional grounds, calling the resolution a “preemptive declaration of war”, an “avoidance of Congressional responsibility”, and a de facto amendment of the US Constitution. He warned his colleagues that “if you do not stop promoting the trend toward government by executive supremacy the American people will soon lose their freedom.” In 1965, when Johnson ordered the bombing of North Vietnam and sent fifty thousand troops into South Vietnam—”This is really war,” the president said that summer. Morse became a prominent speaker at rallies in the growing anti-war movement.
In 1787, the US Constitution explicitly gave Congress the power to “declare war”. When, at the Constitutional Convention, Pierce Butler of South Carolina raised the possibility that the President should use this power, Elbridge Gerry of Massachusetts responded that he “never expected to hear a proposal empowering the executive alone to declare war in a republic.”
Much ink and blood has been spilled on this question since Vietnam, particularly in relation to American military action in the Middle East, Iraq, Afghanistan, and Iran.
Abraham Lincoln, serving in Congress sixty years later, agreed. He said that the delegates had deemed the power to declare war “the most oppressive of all royal oppressions”, and so they had resolved that “no man should have the power to bring this oppression upon us.” If a president were to be given this princely power to wage war “whenever he thinks necessary,” Lincoln warned, “You must permit him to make war as he pleases.”
Successive presidents have actually engaged in military action without consulting Congress, taking advantage of a power reserved for the legislature, a fact of American history over the past century and a half, including during the Trump years. Does the fact of that frequent practice change the Constitution? This question has been the subject of intense legal controversy since the late 1960s.
Reviewing the state of the debate in 1971, Yale legal scholar Alexander M. Bickel addressed the argument that the provision of the Constitution that gives only Congress the power to declare war was informally modified by the executive’s regular exercise of this power. After all, as Louis Brandeis wrote, the Constitution is “capable of evolution.” Bikal was not ready. He argued that there can be evolution, but you cannot by “evolution” extend the term of the presidency, or abolish the Electoral College, nor can you give the executive the power to declare war by force of habit. To be clear, Bikel opposed the American war in Vietnam. But his argument, here, was merely constitutional: “No one should ever rationally believe that the United States could go to war at the behest of the President.”
Much ink and blood has been spilled on this question since Vietnam, particularly in relation to American military action in the Middle East, Iraq, Afghanistan, and Iran. The debate is still divided into two camps. One camp holds fast to the claim that Congress alone has the power to declare war. The other camp argues that the President, as commander-in-chief, has the power to engage in military action to protect Americans in the event of an emergency. Both of those statements could be true and yet it could hardly be called deadlock, or even proper separation of powers. Congress, having repeatedly failed to exercise its war power, can no longer do so effectively. And, what constitutes an emergency is for the President to decide, allowing him, as Lincoln said, to make war at his pleasure.
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“Do American presidents have the power to declare war?”. By Jill Lepore. derive from America Incomplete: 250 Years of Law and GovernanceEdited by Alexandra Natapoff and Guy-Uriel E. Charles. Reprinted with permission from MIT Press. Copyright 2026. This essay is an adaptation of a previously published version New Yorker.
