With voting in the Labour leadership contest underway, David Wearing examines why the Iraq war was such a fundamental call which has much to teach us about a future leader's judgement.

Measured by the significance of their consequences, two key policy judgements are likely to shape the way the New Labour government of 1997 to 2010 is perceived by future historians.

One is the decision to accept and take forward the neoliberal economic philosophy of the previous Conservative government. As a consequence of that decision, the British economy became over-dependent on finance, under-regulated, and therefore uniquely exposed to the near-collapse of the Western banking system in 2008. This in turn handed the incoming Tory-led coalition of 2010 a significant opportunity to attack what remained of the social-democratic settlement that was Labour’s great achievement of the post-war era.

The other seminal New Labour decision is that which saw Britain join a strongly right-wing US government in the unprovoked invasion of Iraq, a clear breach of international law. The war that Britain and America started went on, according to the best estimates available, to take the lives of hundreds of thousands of people, make four million into refugees, unleash torture, massacres and suicide bombings, and devastate a society.

As the debate over the future direction and leadership of the Labour party draws to its close, the past judgements of the candidates and the lessons learnt from the consequences of those judgements provide crucial information for those who will be voting in this month’s leadership election. This article will focus on the second of those major judgements: the decision to invade Iraq, and what this tells us about the choice facing the Labour Party today.

The front-runner in the contest, with the backing of the party establishment and many media commentators, is the shadow Foreign Secretary David Miliband, who voted for the invasion as an MP in 2003. Seven years on, Miliband says that “If I had known at the time that there were no weapons of mass destruction in Iraq, there would have been no need for UN resolutions, no vote in the House of Commons and we wouldn't have gone to war”.

This defence is unsustainable since the hindsight Miliband appeals to is entirely unnecessary. In the first instance, the case that Iraq had weapons of mass destruction was never proven. In his March 2003 resignation speech, Robin Cook expressed the serious and widespread doubts that existed, saying that “Iraq probably has no weapons of mass destruction in the commonly understood sense of the term”.

However, Miliband senior’s line repeats the same absurd logic which premised much of the Iraq war debate; namely that if Iraq had WMD then an invasion was justified. In reality, the idea that Saddam’s crippled state posed any sort of threat to history’s greatest military power, and its numerous allies, was simply not credible.

It is plain that, even if Iraq had managed to acquire some modest WMD capability, its offensive worth would have been zero since use would have guaranteed national annihilation. It is a poor reflection on the judgement of those who supported the war that they were able to entertain such a preposterous notion as that of Iraq posing a military threat to Washington and its allies.

By contrast, the dangers of invading Iraq were all too clear. One entirely predictable danger, for example, was that it would provide a powerful incentive for other nations to acquire effective WMD as a deterrent, lest they find themselves next on George Bush’s hit-list. Another danger was that the invasion and occupation of Iraq would play into the hands of al-Qaeda by providing it with a battle ground in which to launch attacks on Western troops and by confirming the narrative peddled by its recruiting sergeants that the Muslim world is under violent attack from the West.

Indeed, the Blair government was repeatedly warned by the security services that the invasion would exacerbate the terrorist threat to Britain. To provide for the security of the British population is arguably the prime obligation of the state. By taking action that was widely predicted to make worse the very threats they claimed to be concerned about - WMD proliferation and international terrorism - those MPs who decided to support the war failed to honour this basic duty of care.

At the Labour leadership hustings in June, organised by the New Statesman, David Miliband made the somewhat surreal statement - delivered with his usual demeanour of steely seriousness - that the invasion of Iraq had been necessary to “uphold the will of the international community”. This assertion is rather difficult to square with the fact that the US and UK were unable to secure international support for the invasion, the fact that the war was a clear breach of the UN Charter, and the fact that the foreign policy of the Bush administration was characterised by its undisguised contempt for multilateralism, for international law and for the United Nations.

Washington made it clear that the UN could either ratify the decision already made by the White House in respect of Iraq, or be brushed aside in the march to war. Despite a round of intensive bribery and bullying, ratification was not forthcoming, and the war went ahead regardless. If we accept Miliband's intellectual contortions we must understand the “international community” as  whoever will obey the master, whether or not this includes the majority of the world’s nation states or its peoples. In any event, it is difficult to see what more Britain could have done to damage the cause of multilateralism, of a rules-based international system and the ideal of an international community, than to join with an aggressively unilateralist global hegemon in its assault on those principles.

Andy Burnham has offered a more belligerent defence of his vote for the invasion, saying that "I don't back away from the original decision. I think it gave 20 or so million people in Iraq hope of a better life and you just cannot walk away from that truth". Burnham ignores the WMD argument, instead lauding the US-led regime change as a liberating, humanitarian intervention.

No serious person could lament the fall of the odious Saddam. But nor can one continue as though  this constitutes the beginning and the end of our assessment of the Iraq invasion, given everything else that has happened since. Not least amongst the other factors to consider are the hundreds of thousands of Iraqis who, having died in the war that the US and Britain started, will never see the better life that Burnham speaks of. Also worthy of consideration are those who survived, but have lost their husbands, wives, sons, daughters, fathers, homes and livelihoods in the bloodbath that consumed the country in the wake of the invasion.

The key question of judgement here is this: why would Andy Burnham, or anyone else, wish to entrust the liberation of Iraq to the US government under George W Bush? After all, Washington had supported Saddam while he committed his worst atrocities, with some of that support coming from figures in the Reagan-Bush administrations who were later to return to high office under Bush the second. After the Gulf War, the United States had taken the lead in enforcing a sanctions regime on Iraq which, according to UNICEF, led to the deaths of around a million Iraqis, half of them children under the age of five.  Far from weakening Saddam, the sanctions strengthened his regime by forcing his subjects to rely upon it for their survival.

The United States had demonstrated its commitment to liberty and humanitarianism by continuing to support various tyrannical regimes in the Middle East and Central Asia, including Egypt, Saudi Arabia, the Gulf States, Israel’s occupation of the Palestinian territories and Islam Karimov’s particularly cruel regime in Uzbekistan. In light of this, it is not clear why Burnham would look to Washington to attend to the welfare and human rights of the Iraqi people, although it should be noted that, like David Miliband, Burnham was a member of a Labour government which since 1997 had followed the US line throughout this shameful record.

All of this was known at the time that Burnham and David Miliband cast their votes for the invasion. What occurred subsequently ought to have provided them with more than enough reason to end their support for the US-led occupation, and to rethink the view Burnham apparently still holds of the war as an act of liberation. The savage American assault on the town of Fallujah, compared by the Guardian’s veteran foreign correspondent Jonathan Steele to the massacre at Guernica in the Spanish Civil War; the exposure of grotesque forms of torture at Abu Ghraib; the view expressed by one senior British commanding officer, quoted by the Daily Telegraph in April 2004, that US troops saw the Iraqi people as “untermenschen”, and were inflicting “tragic” levels of violence on civilians; all of this makes abundantly clear where “liberation” and “human rights” featured on the invaders’ list of priorities.

Many supporters of the war were no doubt disgusted by these atrocities, but they were a direct and predictable consequence of a war of aggression launched against a fragile and unstable state by a ruthless military superpower. The fact that it took a leading role in the invasion and occupation means that Britain, and the Labour government of the time, cannot stand apart from the horrors that unfolded in Iraq since 2003. It is itself directly implicated in and bears a significant share of responsibility for what became one of the greatest humanitarian disasters of the past decade.

What was relevant to the invasion’s planners was the opportunity to establish a client government and a permanent military presence in an oil-rich state at the heart of the world’s primary energy producing region. Because, once we have dispensed with the aggressors’ self-serving fairytales concerning weapons of mass destruction and the West’s deep yearning to spread democracy throughout the Middle East, we are left with the familiar sight of powerful states seeking to consolidate and extend their power through the effective control of strategically important resources. Even former Federal Reserve chairman Alan Greenspan declared himself “Saddened that it is politically inconvenient to acknowledge what everyone knows: the Iraq war is largely about oil”. In his interview with Andrew Marr this week,Blair described this as a “conspiracy” view. Both party members and the wider public deserve a Labour leader who refrains from insulting their intelligence in this way.

As the US constructed vast military bases and an embassy the size of Vatican City; as it imposed neoliberal shock therapy on the Iraqi economy without bothering to consult the population (also in contravention of international law, and leading to an economic collapse that did much to fuel the ensuing violence); as the US and Britain refused to withdraw in defiance of the known views of the Iraqi people, it should have become abundantly clear to Miliband and Burnham that the invasion had nothing to do with defence or humanitarian liberation, and everything to do with the amoral self-interest that has characterised the behaviour of powerful states at every point in history.

Different questions are raised by the positions of the other candidates. In contrast to David Miliband, Ed Balls has said that “on the information we had, we shouldn’t have prosecuted the war”. He also indicates that this was not his view in 2003 by saying that he would have voted for the invasion had he been an MP at that time. Ed Miliband goes further, saying that he opposed the war from the beginning, and emphasising its significance for New Labour’s decline in fortunes.

Although such self-awareness is welcome, one must also ask why we are only hearing of this opposition now, as opposed to earlier on, when it might have had some impact. When did Balls change his mind about Iraq, and why did he not speak out immediately? If Ed Miliband did oppose the war during the build-up in 2002-03, what form did this opposition take? If it consisted only of telling those close to him what he thought, as opposed to engaging in activism or making public his views along with millions of others around the world, then why was this?

Meanwhile, though the political classes have spent the summer patronising and dismissing the fifth contender, Diane Abbott, the inconvenient fact remains that, unlike her rivals, only she made the historic judgement on Iraq correctly (as she did on the economy), only she made that judgement at the time, without hindsight, and only she took a principled, public stand on the subject when it mattered.

Where the other four contenders are concerned, the common fault - beyond the failure to analyse and to make crucial decisions correctly - is the failure to critique and challenge power. The New Labour project was, at its core, an accommodation with power: with big business and big finance on economic policy, with the right-wing tabloids on social policy, and with US power on foreign policy. The view that this accommodation could lead to progressive outcomes quickly morphed into a complacency wherein the true nature and motivations of power went unchallenged and unexamined. A more critical, sceptical and independent approach would have better served the Labour government in its dealings with the Bush administration over Iraq, as well as in many policy areas closer to home.

These concerns have a direct bearing on the challenges facing the Labour Party today, climate change and the ongoing economic crisis being the major examples. Campaigns for the required reduction in carbon emissions, and against the coalition government’s attempt to force the poorest in society to pay the gambling debts of the financial industry are bound to be opposed by a powerful array of vested interests.

The willingness to articulate a compelling critique of power, and to take a clear stand against those vested interests when necessary, will be the difference between success or failure for the broad left in the crucial battles of the coming years. As Barak Obama is discovering, this is even more true in government as it is in opposition. Voters in the Labour leadership election will have to decide which contender has proven themselves most willing and able to rise to such occasions. The lessons of Iraq prove a telling guide.

David Wearing is researching for a PhD in Political Science, specialising in British foreign policy, at University College London. His articles have been published by The Guardian and Le Monde Diplomatique. He is also co-editor of the New Left Project website.