In June 1950 North Korea attacked South Korea; within a week President HARRY S. TRUMAN committed American air, sea, and ground forces to South Korea's defense. The resulting three-year involvement lasted into the administration of DWIGHT D. EISENHOWER and became the largest undeclared war in American history prior to the Vietnam involvement.
The initial rush of events created enduring confusion about the constitutional basis for the American intervention. On June 25, the day following the attack, the United States obtained a United Nations Security Council resolution ordering North Korean withdrawal. Two days later, with fighting continuing, the Security Council requested U.N. members to assist in repelling the aggression. That day, without congressional approval, President Truman publicly ordered American air and naval support for the South Koreans, and throughout his remaining tenure in office he persistently called the conflict a United Nations POLICE ACTION. The key American decisions had actually preceded the U.N. request, however, and critics, led by Senator Robert A. Taft, convincingly demonstrated that pertinent provisions of the UNITED NATIONS CHARTER (having status as treaty law in the United States) and the United Nations Participation Act gave no constitutional authority to the American President. The necessary agreements for United States peacekeeping forces had never been concluded with the Security Council.
Careful defenders of Truman's actions, especially Secretary of State Dean Acheson, argued that Truman's authority derived from his duty as COMMANDER-IN-CHIEF to protect American interests. One such interest was the preservation of the United Nations as an instrument for peace; another was the security of American forces in the Pacific area. The defenders relied, too, on presidential control of FOREIGN AFFAIRS and on the alleged precedent of eighty-five prior instances of presidential use of military forces without a DECLARATION OF WAR. Not surprisingly, critics also found these sources insufficient, strongly disagreeing about the meaning of Congress's power "to declare war" and about the legal relevance of past episodes of unilateral presidential action. Truman nonetheless followed Acheson's advice and explicitly refused to request formal authorization from Congress.
The war had other constitutional dimensions, as well. In April 1951, after serious policy disagreements, Truman dismissed his...