Military Necessity

The doctrine of “military necessity” in the Japanese American concentration camp experience derives from the U.S. president's executive powers, which entrusts him with defending the nation from all threats, domestic and foreign. Both martial law in Hawai'i and the mass removal and confinement of Japanese Americans along the West Coast were justified on those grounds of “military necessity.” President Franklin Roosevelt's Executive Order 9066, which authorized the mass removal and detention, justifies the order as necessary for “the successful prosecution of the war.” And according to Assistant Secretary of War John McCloy, who conveyed the news to the army's Western Defense Command on February 11, 1942, the president, he said, will authorize the military to take all measures to ensure the nation's security “but it has to be dictated by military necessity …” (Daniels, 65).

The decision to deploy military necessity as the justification for martial law in Hawai'i was an easy one. As the territory's governor recalled of a December 7, 1941, meeting with the military commander who had asked him to declare martial law and suspend the writ of habeas corpus that day: “During the conference I put this question to Gen. Short: ‘As commanding general, charged with the defense of these islands, do you consider it absolutely essential to the defense of these islands that martial law be declared and the privilege of the writ of habeas corpus be suspended?' He answered emphatically: ‘I do.' I then told him that I was reluctant to do as he requested, that I was a civilian unversed in military matters but he was a soldier charged with the duty of safeguarding Hawaii from the enemy, and that I must yield to his judgment as to what measures should be taken in discharging this duty” (Anthony, 8). With that, the governor surrendered civilian democracy for military rule. Thereupon the military governor informed President Roosevelt who agreed with the transfer of powers.

The justification of military necessity for the continent was thornier. All of the president's men were not in agreement. While West Coast politicians agitated for the removal of Japanese Americans in a January 1942a, a government intelligence agency reported to Washington, D.C., “word of mouth discussions [continue] with a surprisingly large number of people expressing themselves as in favor of sending all Japanese to concentration camps” (Daniels, 62). In the midst of those discussions on January 30, 1942, President Roosevelt met with his cabinet to discuss the situation. The military was concerned about “dangerous Japanese” in Hawai'i, members heard, and several, particularly Navy Secretary Frank Knox, expressed their unhappiness that more was not being done in Hawai'i to contain the Japanese menace. At an earlier December 19, 1941, meeting, the cabinet had agreed to intern all Japanese aliens in Hawai'i on an isolated island away from military installations.

Racismnot military necessityprompted the ouster of Japanese Americans. Oakland, California, February 1942. (Library of Congress)

Racism—not “military necessity”—prompted the “ouster” of Japanese Americans. Oakland, California, February 1942. (Library of Congress)

On February 1, 1942, Attorney General Francis Biddle informed the military and War Department during a meeting in his office that he opposed the removal of “American citizens of the Japanese race.” An incredulous provost marshal, the army's chief legal officer, replied: “Well, listen, Mr. Biddle, do you mean to tell me if the Army, the men on the ground, determine it is a military necessity to move citizens, Jap citizens, that you won't help us?” In answer, Biddle repeated his decision to oppose the plan. At that point, John McCloy addressed Biddle: “You are putting a Wall Street lawyer in a helluva box, but if it is a question of the safety of the country [and] the Constitution…. Why the Constitution is just a scrap of paper to me” (Daniels, 55–56). Biddle, the nation's chief legal officer, had cited the Constitution and its protections as applicable to Japanese Americans.

After the meeting, the military suspected Biddle and his Justice Department were simply trying to put the army in a bad light. The legal concerns aside, an army officer reported, “we insist that we could also say that while all whites could

remain, Japs can't, if we think there is military necessity for that.” General John DeWitt, Army commander on the West Coast, added: “they are trying to cover themselves and lull the populace into a false sense of security” (Daniels, 56). Still, the War Department and Army headquarters in Washington, D.C. directed DeWitt not to say anything public about the military's plans for Japanese Americans until a policy was decided upon.

The politicians were not under the same directive. On February 4, 1942, California governor Culbert Olson took to the radio airwaves to warn citizens, “it is known that there are Japanese residents of California who have sought to aid the Japanese enemy by way of communicating information, or have shown indications of preparation for fifth column activities,” thereby stoking public fears. Olson's accusation was patently false, but he went on to announce general plans “for the movement and placement of the entire adult Japanese population in California at productive and useful employment within the borders of our state, and under such surveillance and protection … as shall be deemed necessary” (Daniels, 60).

The army seemed particularly receptive to West Coast politicians who urged the removal, confinement, and deployment of Japanese Americans in their states. As the provost marshal argued, “If our production for war is seriously delayed by sabotage in the West Coastal states, we very possibly shall lose the war…. From reliable reports from military and other sources, the danger of Japanese inspired sabotage is great …” (Daniels, 64). The military's strategy, he wrote, should not be influenced by the need for Japanese American labor, humanitarianism, or fear of retaliation from Japan.

The president's EO 9066, justified on the basis of “military necessity,” affirmed that position taken by most in the military command. Some, including Brigadier General Mark Clark of the Army's General Headquarters, disagreed with mass removal and confinement because of the drain on military personnel required to move, house, and guard the concentration camps for Japanese Americans. But the military did not make the public policy, which politicians in the executive branch of government shaped. Even Attorney General Biddle conceded on February 12, 1942, in correspondence to Secretary of War Henry Stimson, in reference only to issei or non-citizens, “I have no doubt that the Army can legally, at any time, evacuate all persons in a specified territory if such action is deemed essential from a military point of view …” (Daniels, 69). “Military necessity,” thus, provided the cover and justification for a policy largely drawn up by the War Department and ultimately, the president.

Gary Y. Okihiro


Anthony, J. Garner. Hawaii under Army Rule. Honolulu: University Press of Hawaii, 1955, 1975.

Daniels, Roger. Concentration Camps: North America: Japanese in the United States and Canada during World War II. Malabar, FL: Robert E. Krieger, 1981.