Until now, private security contractors working for the State Department, as Blackwater does, have effectively not been covered by either U.S. or Iraqi law, or military regulations. A bill that overwhelmingly passed the House last week would close that loophole. But the law would also require the FBI to establish a large-scale presence in Iraq in order to investigate accusations against private contractors. Law-enforcement officials worry that this would draw valuable resources away from FBI efforts to combat terrorism in the United States. Also, whenever FBI agents venture into Iraq now they are guarded by ... Blackwater operatives. The bureau has sent a team to Baghdad to investigate the Sept. 16 shooting in Nasoor Square, in which Blackwater guards are accused of killing as many as 17 Iraqi civilians. In order to avoid "even the appearance of any conflict [of interest]," according to an FBI spokesman, the agents will be defended by U.S. government personnel.