There was kabuki theater around this, so far as intelligence was involved. Mostly the official faces quietly did nothing. None actively contradicted the narrative. And of course, Tenet (the CIA director at the time) called it a "slam dunk". Most of them were never under oath about any of this - it's not like the US actually investigates or punishes its own war crimes or violations of the UN Charter. In reality, invading Iraq was a Washington consensus position to destabilize that country further after over a decade of civilian-targeted sanctions. Our liberal hero, Joe Biden, happily laid the propaganda on thick through his position as chair of the Senate Committee on Foreign Relations, bringing in hack after hack to testify and make the case via the media apparatus. Very few people in power even publicly questioned the case for a war of aggression, let alone did anything to oppose it, and media narratives were more or less lockstep with them despite record-setting protests. Actually, scratch that: there was a pervasive culture of anti-brown, islamophobic rhetoric that questioned the patriotism (read: right to belong) of anyone who pushed back. Ask anyone that looked vaguely South Asian or Arab at the time.
Of course, I don't want to gice the impression that possessing WMDs has ever been a consistent, valid, or legal justification for being a target of a war of aggression. The only country to use nukes on civilians was the US and I don't see them invading themselves with a "coalition of the willing" since then, though they have certainly been very aggressive.
But I digress. Of course US intel is going to be doing shady things, that's not really debated. The thing I think is most relevant here is the parallel of a lack of media criticism and how easy it is to get folks, and particularly Americans, to absorb headlines and claims without looking any deeper into sourcing, into the history at hand, or even just for now, admitting that there is very little information or ways to get a good handle on the sequence of events, and it's okay to not have a hot take. Opposing a jingoistic fervor is essential to opposing fascism.