Interactive Constitution Essay: Declare War Power

The Constitution’s Article I, Section 8 specifically lists as a power of Congress the power “to declare War,” which unquestionably gives the legislature the power to initiate hostilities. The extent to which this clause limits the President’s ability to use military force without Congress’s affirmative approval remains highly contested.

Most people agree, at minimum, that the Declare War Clause grants Congress an exclusive power. That is, Presidents cannot, on their own authority, declare war. Although it is somewhat more contested among scholars and commentators, most people also agree that Presidents cannot initiate wars on their own authority (a minority argues that Presidents may initiate uses of force without formally declaring war and that Congress’s exclusive power to “declare war” refers only to issuing a formal proclamation).

In the early post-ratification period, the clause’s limit on presidential warmaking was read broadly. Many key founders, including Alexander Hamilton, George Washington and James Madison, referred to the clause’s importance as a limit on presidential power. In the nation’s early conflicts, Congress’s approval was thought necessary – not only for the War of 1812, for which Congress issued a formal declaration, but also for lesser uses of force including the Quasi-War with France in 1798, conflicts with the Barbary States of Tripoli and Algiers, and conflicts with Native American tribes on the Western frontier (all of which were approved by Congress, albeit without formal declarations).

In modern times, however, Presidents have used military force without formal declarations or express consent from Congress on multiple occasions. For example, President Truman ordered U.S. forces into combat in Korea; President Reagan ordered the use of military force in, among other places, Libya, Grenada and Lebanon; President George H.W. Bush directed an invasion of Panama to topple the government of Manual Noriega; and President Obama used air strikes to support the ouster of Muammar Qaddafi in Libya. Some commentators argue that, whatever the original meaning of the Declare War Clause, these episodes (among others) establish a modern practice that allows the President considerable independent power to use military force.

In general, most scholars and commentators accept that presidential uses of force comport with the Declare War Clause if they come within one of three (or possibly four) categories, though the scope of these categories remains contested. First, Presidents may use military force if specifically authorized by Congress. Authorization may come from a formal declaration of war, but it can also come from a more informal statutory authorization. For example, after the September 11, 2001 attacks, Congress authorized the President to use force against those who launched the attacks and those who supported or assisted them. Sometimes, authorizations are fairly specific (as when Congress authorized President George W. Bush to use force against Iraq); sometimes they are more open-ended, as when Congress authorized the use of force to protect U.S. interests and allies in Southeast Asia, leading to the Vietnam War. Most people agree that presidential actions pursuant to such authorizations are constitutional, although there may be debate about how broadly to read any particular authorization. More controversially, Presidents have claimed authorization from informal or indirect congressional actions, such as approval of military spending, assent by congressional leaders, or even Congress’s failure to object to ongoing hostilities.

Second, Presidents are thought to have independent authority to use military force in response to attacks on the United States. At the 1787 Philadelphia convention, Madison described the Declare War Clause as leaving the President with authority to repel sudden attacks. The scope of this power is sharply contested, however. Some commentators think it includes defense against attacks on U.S. citizens or forces abroad, in addition to attacks on U.S. territory; some would extend it to attacks on U.S. allies or U.S. interests, defined broadly. Some commentators think it includes defense against threats as well as actual attacks. Some think it allows the President not only to take defensive measures but also to use offensive force against attackers.

Third, Presidents may use other constitutional powers – principally the commander-in-chief power – to deploy U.S. forces in situations that do not amount to war. For example, President Bush’s deployment of troops to Saudi Arabia after Iraq’s invasion of Kuwait in 1990 probably did not implicate the declare war clause because at that point the troops were not involved in combat. Similarly, deployment of U.S. troops as peacekeepers (as President Clinton did in Bosnia) likely does not involve the United States in war and thus does not require Congress’s approval under the Declare War Clause. More controversially, it is claimed that involvement in low-level hostilities may not rise to the level of war in the constitutional sense. President Obama argued on this ground that U.S. participation in the bombing campaign in Libya in 2011 did not require Congress’s authorization. However, this position is strongly disputed by other commentators. A related argument, also controversial, is that using force against non-state actors such as terrorist organizations does not amount to war, and thus does not implicate the Declare War Clause.

A fourth potential category is using force under the authority of the United Nations, which some commentators have argued can substitute for approval by Congress. Among other things, President Truman argued that his use of force in Korea was a “police action” to enforce the UN Charter, not a war. However, Presidents have generally not relied on this source of authority and it is less well accepted, even in theory, than the prior categories.

The law of the Declare War Clause is unsettled in part because there have been very few judicial decisions interpreting it. In the Prize Cases in 1863, the Supreme Court upheld as a defensive measure President Lincoln’s blockade of the southern states following their attack on Fort Sumter, but was ambiguous as to whether the authority for the blockade came from Article II, from specific statutes Congress had passed in 1795 and 1807, or some combination of both. And in dicta, the Court noted that the President could not begin hostilities without Congress’s approval. Earlier cases, such as Bas v. Tingy (1800), referred generally to Congress’s broad powers over warmaking without giving specific guidance on the President’s power. But in modern times, courts have generally avoided deciding war-initiation cases on the merits, based on rules that limit what types of disputes courts can resolve, such as standing or the political question doctrine. As a result, the precise contours and implications of the Declare War Clause remain unresolved today—leaving resolution of disputes over particular uses of force by the President to the political process.