I placed an asterisk in front of #12 because it is a little far-fetched.
1) Breeds new terrorists.
2) Undermines the U.N.
3) Undermines moderate Arabs.
4) Gives POW status to criminals. Civil authorities should handle.
5) Diverts resources away from civil authorities and puts these resources into the military. This is counterproductive.
6) No WMD. War is unjustified.
7) Undermines Civil liberties.
8) This is a Civil War. Not our fight.
9) We are creating new enemies in addition to new terrorists.
10) We took a good leader out and replaced it with anarchy. I am defining anarchy in this case as being constant warfare, chaos and civil strife.
11) Iraq had nothing to do with 9/11/01.
*12) President Bush is a warmonger. He started the war to get back at Saddam. After all, Saddam took a shot at killing his father.
Pretty solid case. Please let me know if you have any additional that you would like me to add.