We like to think our religion (whatever that might be) is about virtue. What is the right thing to do? Do we do it? If we don't, how do we atone?
Here G_d has us make a choshen of judgement—a breastplate that atones for the perversion of justice. The commentator Rashi says that this one “explains and clarifies words." It seems that justice is about the clarification of words. What did a person mean by their words? Does it explain their actions?
It would be one thing for God to say, "be virtuous." It is another that he has us make an elaborate breastplate to hang over our heart that would lead us into a meditative practice to contemplate how we treat one other.