WIth so much dissent in our own nation, we should have deferred to the findings of the UN team, on the ground in Iraq. Kay/Blix told the world repeatedly that there were not traces of WMD. Those traces we smelled in Iran immediately- they didn't show up in Iraq.
Seriously, the only evidence we had was aerial view of milk trucks, and Bush/Cheney on Meet the Press telling us the world was about to end. No chem signatures like you see in every other nation with WMD (NK, Iran, etc).
If there was conflict and reasonable doubt with the story here, and UK said no WMD, and UN said no WMD... why did they choose to follow the 10% of people telling them what they wanted to hear?
That's easy, people only listen to people that they believe are right.
This isn't the first time poor intelligence has caused a major blunder.
WW2, Vietnam, 9-11, Iraq are just a few of the many times bad intelligence in the hands of someone that wants to believe it causes serious problems.
Also America tends to believe their own information and discounts everyone elses.
Recently Maher Arar was detained and tortured in Syria do to bad intelligence offered by the RCMP and the FBI. America won't investigate and still has him on their watch list.http://en.wikipedia.org/wiki/Maher_Arar