Gordon Brown will need a 'clause IV moment' of his own, putting equality at the heart of Labour's constitution if he is to see off David Cameron's attempt to claim 'social justice' for the Conservatives.

The Labour Party is a democratic socialist party that strives to create a fair and more equal society. We campaign to eradicate poverty and discrimination and to extend opportunities to those denied them because we believe that no citizen's life chances should be determined by the circumstances into which he or she is born. We hold that a free and fair society is founded upon mutual respect, compassion and understanding. We will work internationally with all who share our values, to spread justice and human rights, and to sustain our common environment for generations yet to come.

That is the new 'next generation clause four' unveiled in the Fabian Review Equality special issue, to make clear that a commitment to a 'fair and more equal society' is the party's defining belief and underpin a policy agenda to make life chances depend less on the circumstances into which we are born. This has already won support from significant party figures, and the Fabians say it should be central to the party's future renewal debate.

Sadiq Khan MP is supporting the call, arguing that a new Clause IV centred around equality would act as a clarion call to members and potential supporters as well as a wake up call to lapsed activists'.

Ex-Downing Street policy advisor Patrick Diamond says that 'the Fabians are absolutely right that equality must be central to the debate about how Labour renews itself' while Anne Campbell, defeated by the LibDems after 13 years as MP for Cambridge, says that 'Putting the case for a more equal society at the heart of Labour's future agenda will be essential.'

Fabian General Secretary Sunder Katwala: 'When the Conservatives sign up for the goal of ending child poverty, we can see that the political centre-ground is shifting our way. But voters may hear all three parties campaigning on vague and near identical claims to care about social justice. Labour needs a distinctive manifesto to narrow inequalities which can re-engage voters and drag the other parties further onto progressive ground'

The clause IV initiative is the Fabian Society's first contribution to the major debate which the party will hold about renewal following May's local elections. The Prime Minister last month called for both supporters and critics of the government's reform agenda to take part in a fundamental debate about the core values of the party, on the model of that which led to the new Clause IV a decade ago, called 'building a progressive future'. The Fabian Society will seek to make the emerging debate about inequality central to this, as part of a strand of activities on the 'next decade' agenda over the next year.

The Fabian Review Equality special builds on an extensive debate sparked by the Fabian Life Chances and Child Poverty Commission, launched a fortnight ago by David Miliband and Ed Balls. The Fabian Life Chances report also challenged the Conservatives to sign up to the goal of abolishing child poverty by 2020. The Fabians say that Oliver Letwin's subsequent commitment to that goal shows that the 'battle for social justice' will be a central battleground at the 2009 General Election.

The Fabian Society has always played a central role in revising and rethinking the left in every generation, founded in 1884, joined together with trade unions and others to found the Labour Party in 1900. It is affiliated to the party but editorially, organisationally and financially entirely independent of it. Leading Fabian Sidney Webb wrote the original clause IV in the party's 1918 Constitution with its famous commitment to the 'shared ownership of the means of production, distribution and exchange'. Leading Fabians Hugh Gaitskell and Tony Crosland campaigned unsuccessfully to rewrite the clause after the 1959 election, and the 1990s rewriting of Clause IV was led by Giles Radice's Fabian pamphlet series Southern Discomfort which set out why Labour was failing with southern swing voters. Tony Blair's Fabian pamphlet as leader first signalled his intention to rewrite clause IV.

Like all publications of the Fabian Society, the Fabian Review represents not the collective view of the Society but only the views of the individual authors. The new Clause IV was drafted by Fabian General Secretary Sunder Katwala and Editorial Director Tom Hampson.