Reader dxc suggests a link to this TPM story:
…not only is Blackwater immunized from liability under any Iraqi law, but the State Department has allowed it to operate under less restrictive rules of engagement than any other private military company. As a result, the State Department bears responsibility for the culture of impunity that resulted.
Last year, Congress passed a law placing contractors under the Uniform Code of Military Justice, the law that establishes legal conduct for U.S. forces. Little follow-on work has established what exactly that means for private security companies, however. While the Pentagon has issued a number of so-called fragmentary orders seeking to regulate the private security firms, Blackwater is exempt, since its contracts are with the State Department and CIA. Blackwater isn’t required to keep the U.S. military command informed of its operations or file incident reports to it.