Answer:
These people must interpret the law fairly and independently, with no bias due to/caused by personal feelings, religious values, past experiences, or self-promoting agendas. If they do this correctly then they are practicing ethically and it is important to do so because if they don't they might punish a person for doing something that they did not, in fact, do. This would mean imbalance and unfairness that would offset the entire delicate system that we have created. Sadly, not all of them are ethical, actually, most of them are not. Like most thinks, this had been corrupted in our modern day society under heavy influence since the beginning. So in no way is it our faults today but a result of something that had been pre-existing.