 Earlier in his career, Baker was Law Clerk to John Paul Stevens, Supreme Court from 1977 to 1978.He also clerked for Frank M. Coffin, United States Court of Appeals, First Circuit (1976–1977) and Shirley Hufstedler, US Court of Appeals, Ninth Circuit (1975).He was in private practice with the Washington, DC-based law firm Steptoe & Johnson LLP from 1981 to 1992 and again from 1994 to 2005.