William Howard Taft is the only person to serve as both president and chief justice of the United States. He would have been content to be a judge, but his family - and history - had other ideas. When Theodore Roosevelt declined to run again in 1908, he picked Taft as his successor. With Roosevelt's support, Taft was easily elected president. Following his presidency, he served a stint as a law professor at Yale, then chosen chief justice of the supreme court, where he created a lasting legacy through his reform of the Federal judiciary.