War Powers
Where does the Constitution vest the power to declare war?
What authority does the President have to engage in military conflicts against foreign enemies?
Article I, section 8, clause 11 of the Constitution assigns the power “to declare war” to Congress alone.1 The President has no role in the process, though the President may request a declaration, and once declared, the President, as Commander-in-Chief (C-in-C), has the responsibility for leading America’s military forces during the conflict.
Article II, section 2 assigns the President the role of C-in-C with all the inherent powers associated with this title and position. In practice, presidents have used their C-in-C powers to protect American citizens and military personnel attacked on foreign soil; to defend an ally attacked by a US enemy; and to attack an enemy that has demonstrably threatened the US. Despite what appears to be a straightforward separation of responsibilities, the reality is that Congress’s power to declare war and the President’s C-in-C power are “overlapping authorities.” This overlap has resulted in legal challenges by Congress when the President has appeared to overstep his authority.2 Because the President may choose to send US troops abroad to engage in combat operations when not in an officially declared war, the Congress can (and has) involved itself in those operations. It has the power of the purse, ie. to appropriate money, which it has utilized to limit funds for military operations. Congress has also placed restrictions on the scope of military operations by passing laws that constrains where US forces may strike.3 Presidents from both parties have chaffed against such congressional efforts to check, or worse proscribe, their C-in-C powers.
To better understand what the Framers intended for the executive’s C-in-C powers, let us consider the words of two outspoken proponents of a strong executive. James Wilson, a delegate to the Constitutional convention, said during Pennsylvania’s state ratifying convention:
This system will not hurry us into war; it is calculated to guard against it. It will not be in the power of a single man, or a single body of men, to involve us in such distress; for the important power of declaring war is vested in the legislature at large.
In Federalist Paper #69, Alexander Hamilton wrote:
Secondly. The President is to be commander-in-chief of the army and navy of the United States. In this respect his authority would be nominally the same with that of the king of Great Britain, but in substance much inferior to it. It would amount to nothing more than the supreme command and direction of the military and naval forces, as first General and admiral of the Confederacy; while that of the British king extends to the DECLARING of war and to the RAISING and REGULATING of fleets and armies, all which, by the Constitution under consideration, would appertain to the legislature. The governor of New York, on the other hand, is by the constitution of the State vested only with the command of its militia and navy. But the constitutions of several of the States expressly declare their governors to be commanders-in-chief, as well of the army as navy; and it may well be a question, whether those of New Hampshire and Massachusetts, in particular, do not, in this instance, confer larger powers upon their respective governors, than could be claimed by a President of the United States.
Apparently, the Framers did not intend for the President’s C-in-C powers to be absolute, but rather checked by the legislature.
In the nation’s first 150 years, Congress declared war on Great Britain (the War of 1812, which President Madison reluctantly supported), on Mexico (the Mexican-American War, 1846. This war initiated by President Polk as part of his territorial expansionist agenda. He ordered General Zachary Taylor to pursue Mexican troops into their country, without congressional approval, after the Mexican forces had crossed into Texas), on Spain (the Spanish-American war, 1898) and in World War I. Even without a formal declaration, however, Presidents have generally sought authorization from Congress before sending US troops into conflict zones beyond the US borders.
World War II was the last officially declared war in our history. Since 1941, every military action, large and small, has been legally justified by some other means. The Korean War was conducted as a “police action,” as designated by the United Nations. US involvement was explained as legally necessary because the US was a signatory to the UN Charter.4
America’s involvement in Vietnam’s civil war began in 1955, when President Eisenhower sent US military advisors to South Vietnam after France withdrew its troops. President Kennedy increased the US presence during his brief administration, but President Johnson drastically escalated US troop numbers in 1964 after Congress passed the Gulf of Tonkin Resolution.5
President Nixon dramatically deployed more American forces and expanded the scope of the conflict to neighboring countries, all without Congressional approval. In 1973, to check the president’s war-making authority, Congress passed the War Powers Resolution.6 It mandates that the President notify Congress within 48 hours of placing any US military personnel in situations where hostilities are imminent or active. In addition, the Resolution requires the President consult with Congress before as well as during a troop deployment. And most importantly, it limits the duration of the use of force to 60 days unless Congress formally declares war or specifically authorizes the use of force. If Congress fails take either action, the President is required to withdraw America’s forces. If the Resolution remains in effect, the President may request a 30-day extension before withdrawing US forces.7
Between 1973 and 2001, there were several instances where Congress threatened to invoke the War Powers Resolution in response to a President’s unilateral decision to send US military to combat situations abroad, only to have the President request an Authorization for the Use of Military Force (AUMF) from Congress. Here are four memorable examples:
- In 1980, President Carter received an AUMF for what became his failed rescue mission of American hostage held by Iran.
- President Reagan was granted an AUMF for his invasion of Granada in 1983, to protect American medical students there from Cuban forces.
- In 1991 following Iraq’s invasion of Kuwait, the US Security Council passed Resolution 678 that authorized the use of force against Iraq should it not withdraw its troops from Kuwait. President George H.W. Bush received an AUMF to carry out this resolution when Saddam Hussein failed to end his invasion.
- In 1998, President Clinton’s AUMF covered his attack on al-Qaida after it assaulted the USS Cole, and his deployment of troops to Somalia.
The last AUMF approved by Congress was after September 11, 2001. Subsequent presidents used this AUMF to justify their deployment of American forces in conflict zones. For example, in 2011, President Obama used the (then) 10-year-old authorization to attack Libya and the Islamic State, while President Trump invoked the same authorization in his first term to justify killing a top Iranian general in Syria, and again in 2025 to attack Houthi missile sites in Yemen and to bomb Iranian nuclear facilities.
Of the AUMFs granted, the 2001 AUMF is among the most controversial, because presidents of both parties have used its broad wording to support military action against a wide array of targets, exploiting language that approves efforts “to prevent any future acts of international terrorism against the United States.” President Trump’s Office of Legal Council (OLC) issued its interpretation of the C-in-C powers:
Article II gives the president the power to use force 1. when the President believes there is an important national interest in doing so; 2. when force does not rise to the level of a war in the constitutional sense. Anything below the constitutional level does not count has hostilities.
Such an interpretation of the Constitution leaves much room for presidential action as well as raising additional questions, such as what constitutes a “threat” to the US, and has the US been directly threatened.8
- A declared war between two sovereign nation-states is a formal notice to other nations that the two countries are engaged in a military conflict and that other nations should avoid involving themselves in said conflict. But according to 18 USC section 2331 (4), the term “act of war” means any act occurring in the course of a declared war; an armed conflict, whether or not war has been declared, between two or more nations; or an armed conflict between military forces of any origin.” The difference between a formal declaration of war and an act of war contributes to the confusion over the executive’s authority to initiate a military action. ⇧
- Joshua C. Huder, a senior fellow at Georgetown University’s Government Affairs Institute. ⇧
- For example, in 1969 Congress passed the Cooper-Church Amendment that prohibited the placement of US combat troops in Laos or Thailand. In 1994 Congress reduced the appropriations for Operation Restore Hope in Somalia and for US troops operating in Rwanda. ⇧
- On June 25, 1950, the UN Security Council adopted Resolution 82 that condemned the invasion of South Korea by North Korea. Then on June 27, the UN Security Council passed Resolution 83, which declared North Korean actions a breach of peace and recommended that UN member states provide military and other assistance to South Korea. On July 7, Resolution 84, which created a unified military command under the US, was passed by the Security Council. ⇧
- The Gulf of Tonkin Resolution authorized President Johnson to take military action in Southeast Asia after attacks on U.S. destroyers in the Gulf of Tonkin had been reported. It extended the president’s C-in-C powers to respond and prevent further aggression without a formal declaration of war. In June 1970, Congress repealed the Gulf of Tonkin Resolution by a vote of 81 – 10, reasserting congressional control over the president’s ability to make war. ⇧
- The Senate passed the Resolution (75 votes for, 20 against) on October 10, 1973, with the House voting (238 – 122) on October 12. Nixon vetoed the Resolution on October 24, but the House overrode the veto 284 – 135, as did the Senate by a vote of 75 – 18 on November 7. ⇧
- There are constitutional scholars who think that the War Powers Resolution is unconstitutional because it appears to be a legislative veto. A legislative veto occurs when Congress passes a law that the President must carry out and has the constitutional authority to do so unimpeded by Congress, but Congress inserts language in the law that allows Congress to second guess how the President is implementing the law. In INS v. Chadha, 462 U.S. 919 (1983 ), the Supreme Court declared the legislative veto unconstitutional because it violated the separation of powers. ⇧
- For additional readings on this subject, see Andrew Rudalevige’s articles that have appeared online in Good Authority on January 4, 2020, and June 23, 2025. ⇧