All too often criminal convictions get thrown out because prosecutors "forgot" to provide the defense with exculpatory evidence
that was gathered during the investigation.
Exculpatory evidence covers facts that tend to show that the defendant did not commit the crime, and conflict with the case the prosecutor presented to the jury. If the omission is egregious, the prosecutor could be in trouble for prosecutorial misconduct.
In Kevin Drum's article Manipulating Intelligence
you will see a simple exposition of the "exculpatory evidence" that the Shrubbery hid from the world, when he decided to "prosecute" Saddam Hussein.
The only information that was declassified and presented to the public was information that supported the case for war. The "exculpatory evidence" was redacted and remained classified. Those who knew of its existence could not speak out without violating the law.
Those who criticized the intelligence that was used to support the war didn't know about all of the doubts the intelligence agencies had about that intelligence.
They lied by omission, and they continue to lie.