Don't be so tied up that you miss the forest for the trees.
Congress PASSED two resolutions ... and the first in 1998 authorized the President to procede - even unilaterally - with a regime change in Iraq. The second resolution was more emphatic about taking all necessary action against terrorists and states that support terrorism - after the 9-11 attacks.
The "letter" of the process might not have been followed - by strict constructionist ... but the intent has been more than satisfied. Further requirements benefit the enemy!! (but most of the "peace-niks" would rather Saddam be helped than worry about success in the war on terrorism - and would rather have Saddam stay in power killing hundreds of thousands while whining that U.S. action might kill hundreds OR thousands.)
Mike