Phil Carter has a piece in Slate concluding that contract fighters engaged in combat operations, since they’re not either “soldiers” or “noncombatants,” might fall into the legal category of “unlawful combatants,” with possibly disastrous results. He’s also worried about the problems of discipline and coordination. (Phil doesn’t go into the Constitutional issues, which I regard as substantial.)
Phil has some proposed fixes for the operational problems, but despairs of fixing the legal problems.
He doesn’t consider what seems to me the most straightforward approach: have in Iraq, or elsewhere there’s likely to be fighting, enough regular, uniformed, sworn soldiers, with officers appointed by Act of Congress, to handle any assignment that might involve killing someone, and restrict contractors to support missions.