The chairman of...Blackwater USA is defending his company's guards, who are under investigation over a September shooting incident in which 17 Iraqis were killed...The Iraqi government accuses Blackwater guards of a deliberate, unprovoked shooting...But Blackwater chairman Erik Prince says...the guards were responding to small arms fire while escorting a diplomatic convoy...Prince also said there was no basis for a lawsuit filed last week by the Center for Constitutional Rights. The suit accuses Blackwater of murder and war crimes...Prince contends the suit is politically motivated. "The trial lawyers who filed this lawsuit are the same guys that defended the World Trade Center bombings in 1993, the Blind Sheik, and defended a bunch of killers of FBI agents and other cops," he said...Currently, private American security firms in Iraq are immune from both Iraqi and U.S. military laws. However, the House of Representatives approved legislation that would subject contractors to prosecution by U.S. courts...[includes audio links]