Civil Disobedience: He believes in political association in order to flourish and thus believes in formalized government. To the extent the law conflicts with natural justice, Aristotle would likely side on natural justice. Natural justice was Aristotle's definition for principles one can reach through the use of his/her reason.
Justice: The mean between excess and deficiency is wherein justice lies. Where justice is legal and fair; being virtuous. Then the question becomes what if that which is legal is applied unfairly? Which is the priority- legality or fairness? Thus, it comes back to one's ability to reason... Self-defense is a good example. Is it fair to shoot someone who is threatening your life? Is it legal? The law is convoluted, but a jury's ideas of fair is probably clearer.