The Framers of the Constitution crafted a complex network of provisions dealing with the militia. They believed that there should be a national army, but that resources and politics dictated that the militia would provide the bulk of the forces needed to defend the country. Although they were sensitive to the fear of a standing army and the political concerns of the states, there was one principle on which they agreed: when the states’ militias were needed to defend the country, the President, and not the governors, would be in charge. The phrasing of the President’s power changed over the months in Philadelphia, but the exclusivity of the President’s power was never questioned. The most significant change came from Roger Sherman, who moved the addition “and of the Militia of the several States, when called into the actual service of the US.” This assured that the president could not take the militia away from the states except when properly called forth by Congress under Article I, Section 8, Clause 15.

Yet there remained the question of what the president could do with the militia. William Blackstone, in his influential Commentaries on the Laws of England (1765–1769), declared that the militia could not be deployed overseas. (The militia “are not compellable to march out of their counties, unless in case of invasion or actual rebellion within the realm, nor in any case compellable to march out of the kingdom.”) A possible inference is that, in the context of the American Constitution, any tendency of the executive to wage aggressive war (as the English kings were wont to do) is stymied—not only, it is argued by some, by the Declare War Clause—but also by the fact that the principal land force, the militia, could not be sent to fight on foreign soil. For that purpose, the president would need an army; and Congress firmly held the reins over the army, if only by virtue of the need for a recurring appropriation in every congressional election cycle. Whether that was the original understanding has not yet been conclusively determined. In any event, modern practice has allowed the militia (in its form as the National Guard) to be deployed overseas.

In 1792, Congress passed the Uniform Militia Act, also known as the “Calling Forth” act, permitting the president to call out the militia to put down insurrections or rebellions. This power was initially limited to those events that could not be handled by judicial proceedings or by marshals in the exercise of their duties. The act also required a district judge to certify that circumstances were beyond the control of lawful authority and required the president to alert the insurrectionists to end their activities before the militia could be called out. In the meantime, the government launched three major campaigns against the Indians in the Ohio Territory in 1790, 1791, and 1794. In each case, federal forces were supplemented by large numbers of militia volunteers. But it was the Whiskey Rebellion in the summer of 1794 that impelled George Washington to issue the first formal call for the militia to put down the threatened insurrection. Washington took personal command of the force of 12,950 militiamen from Pennsylvania, New Jersey, Virginia, and Maryland. No president since Washington has taken personal control of the militia when called into the active service of the federal government.

In 1795, Congress passed another militia act, aimed at giving the president the power to call out the state forces in the event of insurrection. This law did away with the certification requirements (but retained the requirement of alerting the insurrectionists to disperse) of the 1792 law and granted the president the authority to call forth the militia when the nation was invaded, in imminent danger of invasion, or when faced with “combinations” against the nation. The key provision of that law was: “That whenever it may be necessary, in the judgment of the President, to use the military force hereby directed to be called forth. . . .”

During the War of 1812, when President James Madison called up the militias, the New England states, opposed to the war and threatening secession, objected to the president’s powers. In response to a request by the governor of Massachusetts, the Supreme Judicial Court of Massachusetts issued an advisory opinion declaring that the governors or commanders in chief of the several states had the exclusive right to determine whether exigent circumstances existed for the militia to be called out. This decision effectively recognized a veto power of governors over the use of their respective state’s militia. It also stood the Constitution’s enumerated powers on their head. Article I, Section 8, Clause 15 and Article II, Section 2, Clause 1 specifically granted to Congress and the president, respectively, the power to call out and command the militia when needed in active service to the United States.

In response to the argument for state control of the militia, Secretary of State James Monroe argued that when the militia is called into the actual service of the United States, all state authority over that militia ends. The militia assumes a position within the regular standing army and is paid by the federal government. Its members become, effectively, United States soldiers. They are subject to the same control as regular army personnel, including command by regular army officers.

In 1827 the U.S. Supreme Court supported the Monroe position. In Martin v. Mott, Justice Joseph Story stated, “We are all of opinion, that the authority to decide whether the exigency has arisen, belongs exclusively to the President, and that his decision is conclusive upon all other persons.” To cement further the right of the president to determine when to call forth the militia, Chief Justice Roger B. Taney declared in Luther v. Borden (1849) that not only is a decision by a president to call out the militia in response to an exigency not subject to state executive approval, but the decision is not subject to judicial review either.

Gubernatorial resistance to the president’s call for the militia reemerged during the Civil War. On April 15, 1861, President Abraham Lincoln called for seventy-five thousand militiamen for three-month terms. The governors of Maryland, Kentucky, Missouri, Tennessee, Arkansas, and North Carolina (the last three of which states eventually seceded) refused, although volunteer units from all those states ultimately fought for the Union. As the war progressed, the bulk of the army came from requisitions from the states and the draft. The militias, relatively small and often not well trained, were marginal.

After the Civil War, the militia fell into desuetude (except for a brief and unsuccessful attempt to constitute a militia, based mostly on the freedmen in the reconstructed South) until it began a slow transition into the National Guard. The National Defense Act of 1916 made the National Guard a component of the regular army. During World War I, President Woodrow Wilson drafted members of the National Guard into the regular army.

In 1957, resisting a federal court order, Governor Orval Faubus ordered portions of the Arkansas National Guard to prevent the entrance of black students into Little Rock Central High School. In the first use of the guard to maintain internal order since the Civil War, President Dwight Eisenhower placed the entire Arkansas National Guard under presidential control and ordered the guard to obey the president and not the governor. The Arkansas National Guard complied.

In the 1980s, governors again resisted a presidential call for the militia (National Guard). Some of them objected to the deployment of their states’ National Guard troops to Central America. Led by Minnesota governor Rudy Perpich, these governors withheld their consent to federally ordered National Guard active duty training, as was their prerogative under then current federal law. In response, Congress enacted the Montgomery Amendment to the National Defense Authorization Act for Fiscal Year 1987, which prohibited governors from withholding consent for National Guard active duty service outside the United States. Perpich filed suit against the Department of Defense, arguing that the Montgomery Amendment was unconstitutional because it infringed on the militia training authority granted to the states under Article I, Section 8, Clause 16. Perpich also sought to enjoin the use of Minnesota National Guard troops in any training outside the United States that did not have the governor’s consent. Ultimately, the Supreme Court upheld the supremacy of presidential control over the operations of the militia when called into actual service of the United States, even abroad, the example of Blackstone notwithstanding. Like James Monroe and Justice Joseph Story, the Court held that a state governor could not veto the use of a state militia when called upon by the nation in accordance with Congress’s constitutional power and the president’s constitutional authority.

Recent presidents have made more use of the National Guard as a reserve, calling units up for long periods of duty abroad in actions in the two Gulf Wars, Bosnia, and Afghanistan.