He is best known for his upset victory over Defence Minister General Andrew McNaughton in the Grey North federal by-election held on 5 February 1945.
This pact was strained in 1942 when William Lyon Mackenzie King's Liberals allegedly backed Joseph Noseworthy of the Co-operative Commonwealth Federation (which had refused to agree to the "truce") in his candidacy against new Conservative leader Arthur Meighen who was attempting to enter the House of Commons via a by-election in York South.
On 1 November 1944, General McNaughton was appointed to Mackenzie King's cabinet as Minister of Defence replacing James Ralston who had resigned as a result of the Conscription Crisis of 1944.
McNaughton had been a believer in an all volunteer military and was appointed to replace Ralston but soon found himself under pressure from the government to enact a limited conscription policy.
During the campaign, Case charged that the former Liberal MP had been forced to resign to make way for McNaughton despite the fact that there were several other vacancies in the House of Commons that needed to be filled.
[5] Despite calls from some quarters of labour that they should not contest the by-election, the Co-operative Commonwealth Federation also stood a candidate, retired Air Vice-Marshal Albert Earl Godfrey, a World War I flying ace.
Case defeated McNaughton in an upset victory, the margin of which was smaller than the number of votes received by the third place CCF candidate.
[2] Case remained in the Canadian House of Commons until his defeat in the subsequent 1949 federal election by Liberal Colin Emerson Bennett.