The military in a democracy

There is an article in today's NY Times about the mercenaries used by my government in Iraq. That triggers a few questions. If in a democracy we cannot get enough people to volunteer to serve in the military to perform the duties that the military is called upon to perform in a foreign land, then should we continue to be involved in that conflict? If we have to resort to mercenaries to fight our wars, doesn't that raise serious issues about support for that war when waged by a "democratic" state? And how is it that when those mercenaries murder civilians with abandon, they are not subject to trial - that no law applies? This last point was the gist of the article. Zero accountability for one's actions is morally suspect at the best of times. To avoid any accounting, any trial, from any sovereign for the killing of a human being is truly surreal to me. Then again, like Alice through the looking glass, I and my nation entered the realm of the surreal in late 2000 and haven't looked back since ...