 Yost operated a private practice from 1976 to 1980, and began working with the Manitoba Department of Justice in 1980.He was involved in behind-the-scenes discussions involving the patriation of the Canadian Constitution, the Meech Lake Accord, and the Charlottetown Accord ("Winnipeg Free Press", 10 May 1998).Initially a supporter of the Progressive Conservative Party, he voted for the Liberals in the 1993 election, out of frustration with Brian Mulroney's failed handling of the Meech Lake Accord.