Is every unjust act unjust?

Today in Philo. we are talking about Socrates' decision to not escape from prison and to die. He explained to Crito that no unjust act can be justified with another unjust act. I was thinking about whether the situation determines the action just or unjust or is the action itself determine its justice. I realize that in a way this is just a circular argument; God very clearly says what is acceptable and what is not, but then He tells His people to go and defies these laws. In these instances they have direct orders from God to defy His laws, but would that not go to prove that actions can be determined just or unjust by the situation.