Correct, the Iraqi court can attempt to persecute but that would require the nations of the accuse to hand over the people involved after the investigation is completed. I really do hope that if these guys are found to be guilty of murdering citizens that their parent country's will serve them to Iraq for justice.

The defense they may use is that under a U.N. resolution American soldiers are immune to being prosecuted in Iraq courts and as they were hired by the American government may considered themselves U.S. troops. The Iraqi Interior Ministry disagrees with this assumption and says these Blackwater employees are not immune to law... so we'll see how it plays out.

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