Callison was the long-term legal advisor to the South Carolina Baptist Convention, the South Carolina Baptist Hospital, and the South Carolina Hospital Association, which he continued to represent long after retirement in 1988 from his law firm. He was the first "hospital attorney" in South Carolina, a role that he filled for four decades. In the state House, Callison served at times on the Education, Public Works, and Ways and Means committees. In 1965, in his first year in the state legislature, Callison ran in a special election to fill South Carolina's 2nd congressional district seat, which was based in the state capital, Columbia and included Callison's home in Lexington. The position opened when second-term Democrat Albert Watson switched his registration to Republican, resigned his seat, and ran for the remainder of his term as a member of the GOP. Watson changed parties because the House Democratic Caucus stripped him of his seniority for having supported the 1964 Republican presidential nominee, Barry Goldwater of Arizona, rather than U.S. President Lyndon B. Johnson. Watson said that he would not "sit back and be bullied and browbeaten by the northern liberals." Callison described himself as "a Mendel Rivers Democrat," referring to L. Mendel Rivers, the U.S. representative from South Carolina's 1st congressional district known for his support of national defense measures through the chairmanship of the House Armed Services Committee. Callison was considered a "moderate" by South Carolina standards because he urged compliance with the Civil Rights Act of 1964, whereas Watson favored resistance to the new law. Watson gained the backing of elder Democratic figure James F. Byrnes, who called the congressional move against Watson "punishment and humiliation". In the special election, Watson secured $20,000 and the services of a national Republican field representative in what he termed "quite a contrast" to his treatment by his Democrat colleagues. Watson defeated Callison with 59.1 percent of the vote. Since Watson's defection and subsequent special election victory, the 2nd has been in Republican hands. Numerous business executives relocated to the Columbia area from the North; other area growth came from upwardly mobile South Carolinians who took positions in insurance, banking, state government, and other enterprises and supported the GOP as they advanced financially. Combined with the growing tide of conservative Democrats switching parties, this has made the 2nd a Republican bastion. The district also then contained several African-American majority counties, including Orangeburg County. Callison is a recipient of the Order of the Palmetto in recognition of his longstanding work for the South Carolina Hospital Association.
