The current constitution of Iraq was approved by an October 15, 2005 ratification vote. The proposed constitution was drafted in 2005 by members of the Interim Iraqi Government to replace the Law of Administration for the State of Iraq for the Transitional Period, which had been put in force by the Coalition Provisional Authority after the invasion and occupation of Iraq by the United States and Coalition forces.
Only three of the 15 Sunni members of the drafting committee attended the signing ceremony, and none of them signed it. Sunni leaders were generally urging the electorate to reject the constitution in the 15 October referendum. A two-thirds rejection vote in three of the country's 18 provinces (of which four are thought to comprise Sunni majorities) would have required the dissolution of the Assembly, fresh elections, and the recommencement of the entire drafting process.
I hope it doesn't turn out like Germany's pre-WW2 Republic did. You can't force democracy from the outside, it needs to come from within.