Neutrality Act, law passed by the U.S. Congress and signed by President Franklin Delano Roosevelt in Aug., 1935. It was designed to keep the United States out of a possible European war by banning shipment of war materiel to belligerents at the discretion of the President and by forbidding U.S. citizens from traveling on belligerent vessels except at their own risk. The demand for this legislation arose from the conviction of many Americans that U.S. entry into World War I had been a mistake. This conviction was strengthened by the well-publicized investigations by a Senate committee headed by Gerald P. Nye of American war loans to the Allies. The Neutrality Act was amended (Feb., 1936) to prohibit the granting of loans to belligerents, and later (Jan. and May, 1937) neutrality was extended to cover civil wars, a step inspired by the Spanish civil war. In Nov., 1939, the act was revised in favor of supplying warring nations on the "cash-and-carry" principle; but U.S. vessels were excluded from combat zones, and U.S. citizens were forbidden from sailing on belligerent vessels. These provisions were lifted by amendment in Nov., 1941, after the lend-lease policy had been established. The act was thus practically out of operation even before American neutrality ended with Pearl Harbor.