What illegal orders! Congress lied?
Congress likely got the lies from the executive, like the CIA, FBI, etc.
It is not like Congress could go and send people like Ambassador Wilson or General Fulford Jr. to Iraq or Niger to investigate.
But the State Dept. did send these people to Iraq and Niger, and they returned saying Iraq had no significant WMD, and there was no attempt to buy yellow cake since 1979, by Iraq.
But it was common knowledge Iraq had no WMD. England, Germany, France, Russia, etc., were all telling us that.
The only people claiming Iraq had WMD were the Israelis and Chalabi.
Both of whom had no credibility at all.
What the military did with Shock and Awe was similar to Germans arresting Jews during WWII.
Some things are so obviously criminal, that one can not get out of the punishment by claiming one was "only following orders".