Legal justice and the process of law and moral justice and a basis of morals are tied together wholly unseparably. A just legal system or system of prosecution and punishment can only be just if they are enforcing just laws and offering just judgement. In order for just laws and just judgements a standard of rightness must be present by which we can measure the justness of any law/judgement. Without a standard of rightness, a set of principles of moral justice, legal systems of justice and systems of retribution and punishment are inherently unjust. If anything is in defense of a social, political or economic system that cannot be proven just, it must be assumed unjust for lack of a standard of rightness.

It is possible to argue that since every individual case is separate and contains such a variety of factors that it is impossible to impose upon it a standard of rightness; the only true justice can be achieved by human intuition from case to case. However, this is, in fact, a standard of rightness, that we leave the decisions to be up to human intuition in all cases. There is a school of moral justice that agrees with you, saying that since individual cases are so different and varying, only human intuition can possibly handle the variances and no iron law can hold up. It is also possible to interpret this evidence in a different way. Every human with the possible exception of psycopaths, has an inborn ability to tell right from wrong in most cases. This is a commonly accepted fact and is, in essence, a major contributing principle to the development of a jury system in the United States. If there is a human standard of rightness and wrongness, it is clear that there is something called "right" and "wrong." It is evident that a general standard can arise from an accordance of human intuition to create perfect justice, an ideal discrimination of right and wrong.

I view that fact that good can cause bad and bad good to be irrelevent, at least in a broad sense. There are those that view that the motives of any action determine rightness or wrongness, others that say the ends justify the means, that the the consequences of an action determine that actions inherent rightness or wrongness. I personally believe that it is a combination of both, a man that would nuke a city because he thought that there was a bad guy in it, a good motive but a surely evil outcome, is evil; a man that would kill thousands of people because he didn't like them and it turned out that they were all planning to kill millions more is surely not good. In judgement, in a moral theory, it would be integral to associate motive and consequences together in a dark stew of good and evil. I agree with you that good and evil are not mutally exclusive, and that in this world, in any world, there is no true good nor true evil. However, I don't believe that these facts act as a barrier to the development of a theory of morals.