If a nation believes the wars they fight are just, then that nation should have no problem with allowing its soldiers to decide whether to fight in specific wars. If the cause is truly just, then the soldiers would be more than willing to volunteer and fight. If the war is not just, then the lack of volunteering soldiers would reveal that the war is not one worth fighting. Voluntary fighting would be a preventative measure from fighting too many wars while at the same time insuring the effectiveness of the military in fighting the wars it does fight.
From a purely military perspective, morale would be much greater if a soldier could make the conscious decision that he believes the war he is to risk his life in is worth fighting.
From a social perspective, the citizens of the United States would know for a fact that the soldiers were not giving their lives away for something they did not believe in.
From a political perspective, having voluntary fighting would have a taming effect on the nation, forcing it to be more particular in where and how often military incursions are undertaken. No longer would leaders be able to send people to war without making a solid and convincing case for that war.
From a religious perspective, this would allow people to join the military that believe in the "just war" theory. Right now, a soldier has to subject their or their religion's opinion of whether a war is just or not to the decisions of the state. When they join the military, they are making a permanent surrender of a religious conviction to the decision of the leaders of that nation. An individuals religious beliefs should not be subjected to the state. Changing service in wars to voluntary service would eliminate the state relegating people's religious convictions to an unnecessary status.
For this to really be effective, there would have to be transparency of information from the top of the executive branch all the way to the soldier in the barracks. Information on why a war should be fought could not be withheld. All citizens would need to be considered equal.
The benefits of allowing soldiers to decide whether to fight in a war outweighs the detriments to such an unorthodox process. Just wars would be decided based upon the conscience of the people rather than the conscience of a select few. The bar for the case for war would be raised. The responsibility for the war would be on the shoulders of those actually fighting it. All soldiers would be allowed to participate with a clean conscience. There is nothing to fear in allowing soldiers to decide whether they will or will not fight in a war if the war is just.
