both occasions not to do so. United States The Anti-Pinkerton Act of 1893 () forbade the U.S. government from using Pinkerton National Detective Agency employees, or similar private police companies. In 1977, the United States Court of Appeals for the Fifth Circuit interpreted this statute as forbidding the U.S. government from employing companies offering "mercenary, quasi-military forces" for hire (United States ex rel. Weinberger v. Equifax, 557 F.2d 456, 462 (5th Cir. 1977), cert. denied, 434 U.S. 1035 (1978)). There is a disagreement over whether or not this proscription is limited to the use of such forces as strikebreakers, because it is stated thus: In the 7 June 1978 Letter to the Heads of Federal Departments and Agencies, the Comptroller General interpreted this decision in a way that carved out an exemption for "Guard and Protective Services". A U.S. Department of Defense interim rule (effective 16 June 2006) revises DoD Instruction 3020.41 to authorize contractors, other than private security contractors, to use deadly force against enemy armed forces only in self-defense (71 Fed. Reg. 34826). Per that interim rule, private security contractors are authorized to use deadly force when protecting their client's assets and persons, consistent with their contract's mission statement. One interpretation is that this authorizes contractors to engage in combat on behalf of the U.S. government. It is the combatant commander's responsibility to ensure that private security contract mission statements do not authorize performance of inherently governmental military functions, i.e. preemptive attacks or assaults or raids, etc. Otherwise, civilians with U.S. Armed Forces lose their law of war protection from direct attack if and for such time as they directly participate in hostilities. On 18 August 2006, the U.S. Comptroller General rejected bid protest arguments that U.S. Army contracts violated the Anti-Pinkerton Act by requiring that contractors provide armed convoy escort vehicles and labor, weapons, and equipment for internal security operations at Victory Base Complex, Iraq. The Comptroller General reasoned the act was unviolated, because the contracts did not require contractors to provide quasi-military forces as strikebreakers. In 2007, the US military was temporarily barred from awarding the largest security contract in Iraq because of a lawsuit filed by a US citizen alleging violation of the Anti-Pinkerton Act. However, the case was later dismissed. Foreign national servicemen The better-known combat units in which foreign nationals serve in another country's armed forces are the Gurkha regiments of the British