By Jon Brain
BBC News, Baghdad
Commending the constitution to Iraq's National Assembly, Humam Hammoudi, chairman of the committee that drafted it, described the moment as a "marvellous experience for all Iraqis".
Much rests on October's referendum on the constitution
They should be congratulated, he said, for this was "a constitution written by Iraqi hands".
However, as the document was read out to MPs chapter by chapter, line by line, the occasion had something of a hollow ring.
For the hands that wrote this constitution may have been Iraqi, but they were also exclusively Shia or Kurd.
All 15 of the Sunni representatives on the negotiating committee stayed away from Sunday's signing ceremony, refusing to be associated with a document they regard with deep suspicion.
So why, after months of increasingly tortuous negotiations, have the Sunnis ultimately rejected this vision of the future Iraq?
The roots of their dissatisfaction lie in the era prior to the US-led invasion of the country when, despite comprising only 20% of the population, it was the Sunnis who held the reins of power through Saddam Hussein's Baath Party.
15 August deadline extended twice
National referendum on constitution by mid-October
Full government elections by mid-December
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The Shias and the Kurds were marginalised. Thousands were terrorised or killed by Saddam's henchmen.
With Saddam now off the scene, the Shias in particular believe it is their turn to exercise power in what they hope will be a peaceful and prosperous Iraq.
To do this, they are determined to sweep away the remnants of the old regime.
The first draft of the constitution stipulated that former senior Baath party officials would be excluded from public office in the future.
The wording has subsequently been toned down, but Sunni leaders believe the revised text will still mean many professionals within their communities being deprived of the right to earn their livelihoods.
The second way in which many Shias, although not all, want to leave the past behind is by loosening the ties to Baghdad.
The constitution opens up the possibility of the Shias having a degree of autonomy in the south of Iraq and enshrines a similar situation which already exists for the Kurds in the north.
The final draft followed weeks of wrangling and compromise
Again the Sunnis are firmly opposed.
They fear this is a development which will lead to the break up of the country.
They are also concerned that it will eventually mean the Shias controlling the oil resources of the south, the Kurds controlling those in the north and them being left with nothing.
The draft document stipulates that oil revenues will be used for the benefit of all Iraqis, but the Sunnis fear that guarantee would be worthless were federalism to become a reality.
Neither are they impressed with the document's provision that a decision on federalism be deferred until the next parliament.
So what happens now?
Well, everything now depends on those disaffected Sunnis.
The draft constitution will be put to the popular vote in a referendum in October.
Under the electoral mechanism to be used, it only needs voters in three of Iraq's 18 provinces to muster a two-thirds majority against the document for the constitution to fall by the wayside.
The Sunnis are dominant in four provinces and so therefore effectively hold a power of veto.
But here is the rub.
To ensure the constitution does not become law, the Sunnis will have to do something they did not do in the January elections - turn out and vote.
That would mean that even in wrecking the draft document they would at least be engaging in the democratic process.
And that could represent a significant development in Iraq's troubled path towards a brighter future.