Clause IV is part of the Labour Party Rule Book which sets out the aims and values of the British Labour Party. The original clause, adopted in 1918, called for common ownership of industry, and proved controversial in later years; Hugh Gaitskell attempted to remove the clause following Labour's loss in the 1959 general election.
In 1995, under the leadership of Tony Blair, a new Clause IV was adopted. This was seen as a significant moment in Blair's redefinition of the party as New Labour, but has in the years since survived beyond the New Labour branding.