We use an adversarial system, which means we have at least two opposing sides that fight for their respective sides before an impartial party who makes the decision. This is an easy concept: lawyer v. lawyer and judge decides. Justice is decided when one party’s facts or reasons in law convince the judge that their perspective is the right one. By pairing every perspective with its opposing perspective we create a system where the most information is gathered and shared and the truth will win out.
Interesting fun fact, according to some the adversarial system originated in the initial practice of trial by combat. While trial by combat was almost entirely useless when it comes to discovering relevant facts and making a logical decision it did provide for certain people (mostly women) to have a champion. And thus the lawyer was born.
This is an extremely useful way of completing a story because the rules of evidence require that both parties give each other and the court the information that they find. This information is then used either to impeach one sides story, which would harm their veracity (capacity for truth-telling), or is used as actual proof of why one side is right or wrong. The rules of evidence are a huge subject and I would love to discuss them (not really) but they could not be covered in one blog post. Anyhow, once the parties have made their discoveries and handed them over to one another and the court there is typically a very clear picture of what has been going on. Therefore, the judge just has to use the facts in the case and the relevant statute and case law to come up with the most reasonable solution.