Justice Midwinter graduated from the University of Manitoba law school in 1977.
In the fall of 2005, Midwinter joined Legal Aid Manitoba as a supervising attorney at the Northlands Community Law Centre in The Pas.
He served a two-year term as chair of the Legal Aid Liaison Committee and has been very active with the Manitoba Bar Association.
Justice Midwinter's involvement in the community has included serving on the board of Brandon Big Brothers Big Sisters and the Brandon United Nations High School seminar.
He served as an artillery officer in the Canadian Forces Primary Reserve with the 26th Field Regiment Royal Canadian Artillery from 1973 to 1993, retiring as deputy commanding officer of the regiment with the rank of major.