William Howard Taft was the nation's 27th president and the 10th chief justice of the Supreme Court. After practicing law in Cincinnati, he was appointed in 1887 to the state superior court. In 1890, President Benjamin Harrison named Taft solicitor general. From 1892-1900 he was a federal circuit judge. In 1900, he was asked to head a commission to end U.S. military rule in the Philippines, which had been ceded to the United States. He was civil governor from 1901-1904, after which he was named secretary of war in Theodore Roosevelt's cabinet.

With Roosevelt's backing, Taft won the Republican presidential nomination in 1908 and defeated William Jennings Bryan in the general election. While Taft has been chosen by Roosevelt to continue the latter's progressive policies, there were differences between them. Taft did institute and complete more anti-trust suits than did Roosevelt. He also supported the income-tax amendment to the Constitution. And, Taft helped to enact a system of postal savings. His administration, however, was better known for its failures.

Taft was not able to mediate differences between various factions of his own Republican Party. He clashed with progressives on the tariff issue, siding with the industrial Northeast. He also clashed on railroad legislation and on conservation policy. Taft's battles with the progressives brought Roosevelt into opposition to his "successor." Roosevelt challenged Taft for the 1912 Republican nomination. Taft won and Roosevelt split away and established the Bull Moose Party. In the general election, Taft finished a poor third. Taft left the presidency and took a professorship at Yale. In 1921 President Warren G. Harding appointed him chief justice of the Supreme Court.