In 1902, President Theodore Roosevelt's Corollary was announced. This proposition modified the Monroe Doctrine which had been adopted in 1823 to close the western hemisphere to future colonization. Due to the financial and political problems in Latin America in the early years of the twentieth century, several European nations wanted to intervene. President Roosevelt reacted by declaring the United States was the international policeman of the Western Hemisphere, not Europe and would intervene in the affairs of Latin America to assure stability. Latin American countries often resented the interference in their affairs and what they believed to be U.S. imperialism.

As World War I began winding down, Wilson and his advisors, began to formulate plans for peace. Wilson drew up a statement which came to be called the Fourteen Points that he delivered to Congress in January 1918. In the speech to the joint session of the United States Congress, President Woodrow Wilson summarized three major goals in his Fourteen Points for ending the war and attempting to attain lasting peace for not only Europe, but the world. The goals were as follows: A. Improved international relations—Removal of international trade barriers, honor freedom of the seas, advocate open communication with no secret alliances in an international association of nations, and allow for self-rule of nationalities. B. Restoration of territories—Return to pre-war boundaries and make fair adjustments of all colonial claims. C. Restriction on military strength—Military reductions for all nations, especially Germany including demilitarization along the Rhine River. The most controversial part of the proposal was the creation of a League of Nations described in the 14th Point. Both former President Teddy Roosevelt and Senator Henry Cabot Lodge led opposition in the U.S. Senate to ratification of the treaty which had been negotiated in France and included the League of Nations. Against the advice of his doctors, Wilson set out on a railroad tour to build up public support for ratification of the treaty. In October 1919, Wilson suffered a stroke which left him an invalid for the rest of his life. Wilson continued to refuse to compromise on his position, and as a result, the U. S. Senate failed to acquire the two-thirds vote needed to ratify the treaty and the proposed League.

After the United States entered World War I, the U. S. Congress in 1917 instituted a military draft when it passed the Selective Services Act. Also in 1917, Congress passed the Espionage Act which made it a crime to cause or attempt to cause insubordination in the military and naval forces or to obstruct the recruitment or enlistment of persons into the military service of the United States. Charles Schenck, the General Secretary of the Socialist Party, opposed U. S. participation in World War I. He was arrested and prosecuted for violation of the Espionage Act after 15,000 leaflets traced to Socialist Party headquarters urging resistance to the draft were sent to men who had been drafted. The leaflet quoted the Constitution’s Thirteenth Amendment prohibiting slavery or involuntary servitude, asserted that the Selective Service Act violated the amendment, and that a draftee was little better than a convict. It suggested that the draft was despotism in its worst form and was a wrong against humanity in the interest of “Wall Street’s chosen few.” It urged draftees not to submit to intimidation and to assert their rights. It described even silent consent to the draft law as helping to support an infamous conspiracy. Schenck was convicted in a U. S. District Court and appealed his conviction to the Supreme Court where he argued that the leaflets should be protected by the First Amendment’s freedom of speech and press.

A unanimous Supreme Court upheld Schenck’s conviction. In one of the most memorable Supreme Court opinions in history, Justice Oliver Wendell Holmes wrote for the Court: “We admit that in many places and in ordinary times the defendants in saying all that was said in the circular would have been within their constitutional rights. But the character of every act depends upon the circumstances in which it is done. The most stringent protection of free speech would not protect a man in falsely shouting fire in a theatre and causing a panic. … The question in every case is whether the words used are used in such circumstances and are of such a nature as to create a clear and present danger that they will bring about the substantive evils that Congress has a right to prevent.” Thus, the Court ruled that speech can be limited in wartime.

The so-called “clear and present danger rule” first enunciated by Justice Holmes in Schenck quickly became the test by which a majority of the Supreme Court judged freedom of speech cases for many years to come.