Who has the power to declare war in the United States? That sounds like a simple question, but disagreement between Congress and the President about the answer has become a frequent problem throughout American History.
On the one hand, the Constitution is very clear: Article I, Section 8 grants Congress the power to declare war. That means the United States can only formally go to war—with all the legal and practical consequences that brings—if majorities in both houses agree to do so.
At the same time, however, Article II, Section 2 makes the President Commander in Chief of the armed forces, giving the President and his Cabinet the power not only to draw up the defense budget and appoint commanders, but also to station the armed forces and use them in an emergency.
Congress approves the budget, ratifies treaty commitments, and provides oversight over the armed services, but day-to-day management of the military is in the hands of the President and the Department of Defense. As if to make the relationship that much more fraught, the Secretary of Defense is appointed by the President, but, like all Cabinet members, must be confirmed by the Senate, and is required by law to report regularly to Congress on the Department’s activities.
Believing that the Legislative and Executive branches would respect each other’s role in “providing for the common defense,” the Founders also assumed the President would not use his powers as Commander-in-Chief to involve the United States in an armed conflict without a formal declaration of war from Congress. And, for more than 150 years, American foreign and military policy was limited enough to keep that balance in place.
Even following World War I, the Senate rejected the Treaty of Versailles and the establishment of the League of Nations, because many Americans feared that President Woodrow Wilson had gone too far in committing the United States to possible conflicts, and that membership in the League would result in the United States being drawn into a war without Congressional input.
Although careful observers will note that even during those first centuries, the United States waged wars against Native Americans without formal Congressional declarations, and the absence of a declaration of war didn’t make the Civil War any less of a war either. The United States has only formally declared war five times—on Britain in the War of 1812, on Mexico in 1846, on Spain in 1898, and in the two World Wars. Congress has not officially declared war on anyone since June 1942, when it declared war on Nazi Germany’s allies Bulgaria, Hungary, and Romania.
Since the beginning of the 20th century, however, changes in American global commitments have increased the President’s independent power over American armed forces, causing tensions to erupt between the President and Congress. Whether dispatching occupying forces across the Caribbean in the 1910s and 1920s, sending peacekeepers to the Middle East, or even engaging in full-scale military operations in places as diverse as Korea, Vietnam, Grenada, Afghanistan, and Iraq, many Presidents have committed the United States to military action without formal declarations of war. And during the Cold War, the need to be prepared to deal with a surprise nuclear attack on short notice inspired a system which gave the President the power to unleash perhaps the final war in human history without consulting Congress at all.
As a rule, Congress has been reluctant to insist on formal declarations of war, reserving that step for only the gravest national threats. At the same time, however, Congress has been equally reluctant to restrict the President’s ability to act in an emergency, especially when the President’s party also enjoys congressional majorities. Problems emerge in the gap between full-scale war and emergency actions, and those problems become as much a product of politics as of strategic calculation. When public outcry against a Presidential action becomes an issue, both houses have tried to control the expansion of Presidential military power through legislation and budgetary oversight.
Congress’s greatest success on that score came in 1973, with passage of the War Powers Act, which requires the President to notify Congress of any combat deployments within 48 hours and forbids any action for longer than 60 days without a specific Congressional authorization. This legislation was a direct result of the gradual escalation of the Vietnam War since 1964, during which Presidents Johnson and Nixon had used the very broadly worded Gulf of Tonkin resolution to deepen the American commitment while avoiding a declaration of war. As an indication of how fraught the relationship between Congress and the President remained, the War Powers Act only passed when Congress overrode a veto from President Nixon, who claimed the Act was an unconstitutional restriction on Presidential power as Commander-in-Chief.
Despite its controversial beginnings, the War Powers Act has established an uneasy truce in the struggle over war powers. In 1991, President George H.W. Bush relied on a congressional resolution for the First Gulf War, just as President Clinton relied on a similar resolution in 1999 to support American participation in the NATO operations in Kosovo. In our own time, George W. Bush and every President since has based the ongoing US “Global War Against Terror” on an open-ended 2001 Resolution declaring “That the President is authorized 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.”
Such resolutions satisfy political demands, but dodge important legal and practical questions—about war aims, timetables, how to measure success and failure, and the role of Congress in managing the fight.
Disagreements about the proper balance between Congressional and Presidential power have kept lawyers, politicians, and diplomats busy since America’s founding. It is a conflict that is likely to persist as long as the Republic endures.