The 1st 2 sources taken together explain thoroughly that the decision for Operation Iraqi Freedom was correct on law and policy grounds. Saddam was guilty of material breach across the board for casus belli, including the non-negotiable disarmament and terrorism mandates of UNSCR 687 as well as the cornerstone humanitarian mandates of UNSCR 688.

When Saddam chose to call our bluff again rather than comply in his "final opportunity to comply" under UNSCR 1441, which was also our final opportunity to enforce Saddam's compliance, the decision for America to submit to Saddam's breach boiled down to trusting an unreconstructed, evidently rearming and terrorist Saddam.

Since when do United Nations resolutions have anything whatsoever to do with Constitutional law? The Constitution is the recognised law under which the Federal government must abide, by definition.

Moreover, reading through the text of the actual AUMF resolution, the resolution states clearly that the President was authorised to use force to "defend the national security of the United States against the continuing threat posed by Iraq". Which is all fine and dandy.

Except… where was the threat, exactly?

The first two sources you provide point convincingly to Saddam Hussein's attempts to use state-sponsored Islamic terrorism against targets- in Europe and, overwhelmingly, the Middle East. Where, exactly, was the direct and terrible threat to the US that would have justified an all-out invasion?

The answer is that there wasn't one.

The Bush Administration had its chance to make a convincing case for intervention before the world in 2003. His presentation was an utter failure.

And if, indeed, large quantities of WMD stockpiles were unaccounted for, and Iraq's WMD program was indeed rapidly growing despite US-enforced no-fly zones and UN sanctions, why was evidence of this not uncovered after the US invasion? In spite of initial near-total control of the US military over Iraq's national infrastructure?

The only reasonable answer, after 12 years of repeated failure to prove the "immediate WMD threat" canard, is that there was no real threat.

The reality is that President Bush's actions were made on deeply questionable, though not necessarily outright incorrect, Constitutional grounds; they destabilised the region, badly; they have now embroiled the US in 4th-Generation warfare, a form of fighting that the US military has proven utterly incapable of fighting beyond a handful of limited successes; and has severely drained the American fisc in a poorly-defined, poorly-executed, utterly unnecessary exercise in imperial overreach.

This episode will probably be remembered by future historians as America's "Syracuse Expedition", the adventure that destroyed an empire, and with it a once admirable and virile culture.

When Saddam chose to call our bluff again rather than comply in his "final opportunity to comply" under UNSCR 1441, which was also our final opportunity to enforce Saddam's compliance, the decision for America to submit to Saddam's breach boiled down to trusting an unreconstructed, evidently rearming and terrorist Saddam.

You trusted unreconstructed, evidently rearming and terrorist Saddam. Presidents Clinton and Bush did not.

Clinton: "Heavy as they are, the costs of action must be weighed against the price of inaction. If Saddam defies the world and we fail to respond, we will face a far greater threat in the future. Saddam will strike again at his neighbors; he will make war on his own people. And mark my words, he will develop weapons of mass destruction. He will deploy them, and he will use them."

Bush: "Trusting in the sanity and restraint of Saddam Hussein is not a strategy, and it is not an option."

As far as what happened to Iraq (and the region) after President Bush left office, see the 3rd source + learning-curve.blogspot.com/2014/06/the-fall-of-mosul.html.

Where is the direct evidence that Saddam Hussein genuinely would have used CBN weapons, that could have been traced back to him, against American targets?

Saddam Hussein's biggest concerns, beyond defying the embargoes imposed upon him by the US and the UN, amounted to the preservation of Ba'athist power with him at the head of Iraq's national power structure. His biggest threat was not the US. It was not Israel. It was Iran.

In the process of invading and destroying the Iraqi regime, the US simply removed one of the major regional players that could have counterbalanced an even less rational and even more dangerous actor in the form of Iran. And it replaced a relatively strong centralised (though evil) Ba'athist state with, basically, no real state at all.

Most of the arguments provided in favour of OIF in your second link amount to nothing more than retreads of the usual appeals to regional stability, the (uncontested and undeniable) fact that Saddam was a brutal and evil abuser of his own people, and the need to secure ambiguous "American interests" in the region. Yet the region is now more unstable than ever, the Iraqi people have experienced death and destruction on a scale that even Saddam never dared inflict upon them, and America is now, thanks to its adoption of revolutionary fracking technologies, less dependent on Middle Eastern energy resources than at any time in nearly a century.

The results of 15 years of nation-building efforts, in regions that neither want nor understand Western-style democracy, human rights, equality, and culture, have been a colossal expenditure of blood and treasure for no gains whatsoever. Iraq is lost. Afghanistan is being lost. The Middle East is caught between the rising forces of ISIS and the declining forces of existing dictatorships. And caught up in the middle is America's rapidly deteriorating overseas empire.