In 1945, the Society boasted seven members of the government among its members, including two of its Honourable Vice-Presidents, Sir Stafford Cripps and Clement Attlee. John Platts-Mills had been elected as a Labour MP and D N Pritt as an independent MP. Both rapidly fell out of favour with the Labour government.
The Society threw itself into lobbying for a system of legal aid and the Legal Aid and Advice Act was passed in 1949. 'Law Reform Now' (1947), advocated a comprehensive criminal justice bill, the abolition of capital and corporal punishment, divorce reform and more effective rent restrictions, amongst other proposals.
At the same time, relations between the Labour Party and the Society were becoming more strained. The Labour Party had expelled Sir Stafford Cripps in 1939 (subsequently re-admitting him) and D N Pritt in 1940. The Society rejected the Labour Party’s list of proscribed organisations and continued to allow Communist Party members to join.
In 1948, Platt-Mills was expelled from the Labour Party for sending a congratulatory telegram to Pietro Nenni, the Italian socialist leader who had formed an alliance with the Communists and achieved substantial electoral successes. In December 1948, Gerald Gardiner (later Labour Lord Chancellor 1964 – 1970) tabled a motion to disqualify from Haldane membership anyone "who is a member of a political party other than the Labour Party or of any body membership of which renders him [sic] ineligible for membership of the Labour Party". This was a direct attack on Communist Party members and sympathisers within the Society. The motion was defeated at a highly charged AGM. After a series of split executive meetings, a second motion, restricting membership to members or sympathisers of the Labour Party, was put to a members’ ballot. It received the support of a majority of the membership but not the requisite two-thirds required and so it fell. The anti-Communists walked away, forming the Society of Labour Lawyers, and the Haldane Society withdrew its affiliation to the Labour Party. Ever since, we have remained firmly socialist, but equally committed to independence from any individual political party.
During the 1950s, the Society struggled on, despite being denounced by politicians and in the mainstream press for links to the International Association of Democratic Lawyers and for campaigning against the execution of the Rosenbergs in the US. The IADL was certainly Soviet-dominated at the time and this resulted in a great deal of debate and controversy within the Society itself. The Society also provided legal assistance to anti-colonial struggles, and sent observers to trials abroad. It continued lobbying for law reforms, publishing on rent controls, women’s rights, the legalisation of homosexuality, race discrimination, prisons, legal aid and other topics.