William Howard Taft's legacy mostly boils down to two bits of grade-school trivia: He was morbidly obese, and one time he got stuck in a bathtub (though the truthfulness of that story is up for debate). A much cooler accomplishment of Taft's? He was the only president to also serve on the Supreme Court.
Taft began his career in law. After graduating from Yale (where he was a member of the infamous Skull and Bones secret society, which his father founded) and finishing law school at the University of Cincinnati, he opened a private practice after a brief stint as a tax collector—an appointment given to him by President Chester Arthur. Within a few years, he was appointed judge of the Superior Court in Cincinnati, and shortly after that, President Benjamin Harrison made the 32-year-old Taft the youngest-ever Solicitor General of the United States. And toward the end of the 19th century, Taft served as the first dean and professor of constitutional law at his alma mater, UC.
All of Taft's ambitions were in law—not the White House. Taft had been serving as President Theodore Roosevelt's Secretary of War, and though Taft had earlier had to turn down two Supreme Court opportunities because of his duties in the Philippines (during his post as Governor-General, an appointment by President William McKinley), the promise of a Supreme Court seat was still his greatest aspiration. "I have not the slightest ambition to be president," Taft told a friend, adding that the thought of campaigning "is to me a nightmare" and that all of his ambition was "to go on the Bench."
But, as fate and politics would have it, Roosevelt pushed Taft to run for the presidency in 1908. Supreme Court opportunities came and went, and Taft, much to his chagrin, became the Republican frontrunner. He ran out of a sense of duty, won the election, and went on to have a fairly average one-term presidency (though to be fair, Roosevelt was a hard act to follow). While in office, he appointed six justices to the bench, which must have been a difficult task, considering even his wife acknowledged that Taft "never did ... cease to regard a Supreme Court appointment as more desirable than the presidency."
After he left the White House, Taft bided his time as a professor of constitutional law at Yale and a proponent of international peace-keeping organizations. Then, in June 1921, following the death of the chief justice (whom Taft had appointed 11 years earlier), President Warren Harding had a chance to fulfill Taft's life ambition. The nomination was met with almost unanimous support, and Taft took the oath of office as Chief Justice of the Supreme Court in July 1921.
In his new position, Taft became the first and only person to lead two branches of government, and the only former president to swear in subsequent presidents (both Coolidge and Hoover). Taft was so happy with his nine years on the bench—he stepped down the month before his death—that he once noted, "I don't remember that I ever was President."