James Deverell Horsman was born in Camrose, Alberta in 1935 to George and Kathleen Horsman. He grew up in Meeting Creek with his grandparents while his mother and father served overseas in World War II. His family later moved to Moose Jaw, Saskatchewan. Horsman moved west in the 1950s to study at the University of British Columbia. At UBC, Horsman attained a Bachelor of Commerce degree in 1959 and a year later attained a Bachelor of Laws. During this time Horsman participated in a number of extra curricular activities including a member of UBC Alma Mater Society, the Coordinator of Activities and the Coordinator of Publications. After University Horsman moved back east to Calgary to start practicing law, he moved to Medicine Hat a short time later after visiting family and meeting a potential law partner. After moving to Medicine Hat he met Betty Whitney, a local High School teacher. Horsman married her in 1964. They have three daughters.
Political career
Horsman became involved in the Alberta Progressive Conservatives in the early 1960s. He served on the party's executive council as Vice President for Southern Alberta before running for political office. Horsman first ran for a seat to the Alberta Legislature in the 1967 general election, in the electoral district of Medicine Hat. He was defeated by Social Credit incumbent MLA Harry Leinweber. Horseman would run again in the Medicine Hat-Redcliff electoral district in 1971 and lost to Social Credit candidate William Wyse. Horsman ran against Wyse again in the 1975 general election and was successful this time, defeating him by 100 votes. In 1979 Medicine Hat-Redcliff was abolished due to redistribution, and Horsman ran for re-election in Medicine Hat that year. He won by nearly 8,000 votes over his nearest opponent. Horsman won by another large majority in the 1982 general election. Horsman's share of the vote was cut in half in the 1986 general election, but he still won by a comfortable margin. He won again handily in the 1989 general election. He retired from the Assembly at dissolution in 1993. Horsman would serve a number of roles in provincial cabinet including Minister of Advanced Education and Manpower, Minister of Federal and Intergovernmental Affairs, Attorney General and Provincial Secretary, Government House Leader and Deputy Premier. As Minister of Federal and Intergovernmental Affairs Horsman was responsible for constitutional negotiations for the 10 years following the Patriation of the Constitution until the Charlottetown Accord.