 Clayton served as the United States Attorney in Judge Parker's court from 1874 until 1893, with the exception of the four years comprising the first non-consecutive term of Democratic President Grover Cleveland.During his 14 years in this position, Clayton had charge of over 10,000 cases (including misdemeanors) tried before the court and, during that time, he convicted 80 men of murder—a number greater than any other prosecutor in the United States—and 40 of these men were executed.Clayton was known as "the ablest prosecutor in the Southwest."