 After completing his clerkship, Kleinfeld served for three years as a part-time United States Magistrate of the United States District Court for the District of Alaska.He was nominated to a seat on the United States District Court for the District of Alaska by President Ronald Reagan on March 26, 1986, confirmed by the United States Senate on May 14, 1986, and received his commission on May 15, 1986.His service terminated on October 7, 1991, due to elevation to the Ninth Circuit.