The Open Turn debate took place in 1991 within the Militant tendency of the British Labour Party. The debate was the result of disagreement over whether, in the changed political situation of the time, the organisation would best be able to win support for their form of Trotskyism (for them Marxism) amongst the working class as entryists within the Labour Party, or as an independent political party.
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Open Turn (politics) Wikipedia(Text) CC BY-SA