The Toronto branch of the Canadian Civil Liberties Union was renamed the Civil Liberties Association of Toronto (CLAT) in 1940, and took up the cause of challenging Quebec's repressive Padlock Act in the thirties and forties. During the Second World War the organization focussed most of its efforts highlighting abuses under the federal government's Defense of Canada Regulations, and it had little to say about the internment of Japanese Canadians. By 1946 it was one of only a few civil liberties groups in Canada that was still active. The CLAT opposed the government's handling of the Gouzenko Affair (albeit hesitantly, as the liberal members of the CLAT feared being associated with communists) and joined a coalition of groups formed in 1945 (Cooperative Committee for Japanese Canadians) opposed to the deportation of Japanese Canadians which brought together groups of Japanese, unions, women and social gospel advocates. In the late 1940s the CLAT morphed into the Association for Civil Liberties and was a leader in the movement in Ontario for anti-discrimination legislation alongside the Jewish Labour Committee.

Ross Lambertson describes the leadership of the CLAT as follows: The executive and council of this new group was eminently 'respectable' -- its president was B.K. Sandwell of Saturdav Night and he was assisted by many well-known social democrats, leavened by a smattering of liberals and conservatives. lnitially the
organization had a completely open policy about accepting new members, but by early 1941 the communists were attermpting to elect some of their supporters to the Council, and the CLAT executive was planning the adoption of a rigorous membership policy as well as seeking out new members on the right. ... No complete list of the CLAT executive and Council seems to be available for 1945, but it is clear that by 1944 the organization was still dominateci by 'respectable' members of
the non-communist left and the right. The wealthy businessman Sir Elisworth Flavelie was president, and the vice-presidents were the writer Morley Callaghan, the head of the Workers' Educational Association (WEA), the CCF MPP L.W. Noseworthy, and the principal of University College, Malcolm W. Wallace. The CLAT council consisted of well over 40 people, including the lawyer and CCF activist, F.A. Brewin; CAAE President E.A. Corbett; Canadian Forum editor Eleanor Godfiey; Toronto Sun editorialist Margaret Gould;' the well-connected educator Mrs. W.L. Grantf; CCF activist Professor G.A. Grube of the University of Toronto; Ontario CCF leader E.B.
Joliffe, the Anglican niinister Rw. Dr. W.W. Judd; the author and former CAAE employee R.S. Lambert; CCF MPP Agnes MacPhail; CCF MPP and Steelworkers Director Charles Millard; the Reverend J.R. Mutchmor of the United Church Board of Evangelism; B.K. Sandwell of Saturday Night; Clifford Sifton, owner of the Winnipeg Free Press; Mrs. C.B. Sissons, the president of the Women's International League for Peace and Freedom; and George Tatham, a pacifist academic at the University of Toronto." (Lambertson, 42).