"Besides, I'm not really sure how American law leads to the 9/11 attacks in your black and white world."

Clinton doctrine stopped the CIA and FBI from investigating and pursuing terrorists and their activities until they comitted a crime. Essentially giving them a free shot. Same application of the law used on citizens. We cannot be arrested or detained until we comit a crime. It's well documented in the 911 report and has been widely discussed for years. There is a great PBS frontline documentary on it's impact on 911.