In the 1960s, Fellman became active in Wisconsin state government. He wrote speeches for Governors Gaylord A. Nelson and John W. Reynolds, Jr. In 1959, he was appointed to the governor's Commission on Human Rights and served for nine years. They initiated surveys and drafted legislation, such as the fair housing bill submitted to the state legislature in 1965. In 1960 and 1963, he was named to the Governor's Commission on Constitutional Revision. They were tasked with "drafting of the actual texts of suitable constitutional amendments, the publicizing of their purpose and the promotion of their adoption." Among the notable changes that resulted was the increase of the term for governor from two years to four years beginning in 1970. In 1970, he was appointed by Chief Justice E. Harold Hallows of the Wisconsin Supreme Court to be chairman of the Committee to Recommend Rules on Use of Sound and Camera Equipment in the Courtroom and to advise the court and develop specific recommendations for use of such equipment, which was prohibited at that time.