Leading article: The case for an inquiry is stronger than ever

They will not let it lie; and quite right too. Yesterday, Rose Gentle and Beverly Clarke, whose sons were killed while serving in Iraq, took their demands for an inquiry into the 2003 invasion to the highest court in the land. Over the next few days, a panel of nine Law Lords will hear the argument that the Government should be ordered to establish an independent inquiry into the decision to go to war five years ago.

Mrs Gentle and Mrs Clarke contend that the second article of the Human Rights Act, which guarantees the right to life, obliges the Government to take reasonable steps to ensure that its service personnel do not face the risk of death except in lawful military activities. They believe that Iraq was an illegal war and that the Government thus broke the military covenant. They feel that, under the circumstances, the Government should be compelled by the judiciary to establish an independent inquiry into how the decision to invade was reached.

The two mothers' case was dismissed by the Court of Appeal in December 2006, when judges ruled that decisions concerning war and peace are for governments alone to take. One suspects it will be an uphill battle for Mrs Gentle and Mrs Clarke's legal team to persuade the law lords to overturn this verdict. But whether this particular attempt to force an inquiry is successful or not, the case for a public reckoning over Iraq is stronger than ever.

The deaths of 174 British soldiers in Iraq make an eloquent argument for an impartial inquiry. But the case goes far wider, as the Fabian Society argues today. Questions about the invasion's legality in the absence of a specific United Nations resolution authorising the use of force will not go away, no matter how badly ministers wish to draw a line under the controversy. We also need to know more about the intelligence that led to utterly inaccurate claims over Saddam Hussein's weaponry. The abject failure of Parliament, in particular the main opposition party, to hold the Government properly to account over the decision to go to war also needs to be scrutinised.

The evasive tactics from the Government are looking extremely tired now. Ministers point to "four inquires" into the conflict. But all of these – Hutton, Butler and two parliamentary committee investigations – were narrowly drawn and failed to examine the all-important political decision to go to war. The argument that the leader who took the fateful decision has departed office is similarly inadequate. As personally culpable as Tony Blair was, this is not a simple question of the former prime minister's place in history. It concerns the global reputation of the United Kingdom. We need to determine the roots of the conflict to prevent such a catastrophe occurring again.

When the case for an inquiry was debated in Parliament 15 months ago, ministers argued that such a probe would have a demoralising effect on our troops on the ground. But UK forces have withdrawn from Basra and handed formal control to the Iraqi army. And we are told that the 4,500 British servicemen and women in Iraq are to be gradually pulled out. That particular excuse for Government inaction will no longer wash. Nor will practical objections. The Winograd Commission into the 2006 Lebanon war, established by the Israeli government, has demonstrated that it is perfectly possible to conduct rigorous inquiries into recent conflicts.

Finally there is the political case for an inquiry. Gordon Brown has ordered reviews into seemingly everything since becoming Prime Minister, from super-casinos to cannabis. Does he seriously argue that the nation's gravest foreign policy disaster since Suez does not merit at least equal scrutiny?