Trier of fact 

The person or group who determines the outcome of a case. In a criminal or civil case, this is usually a jury. In a family law proceeding, it is the judge. They are called the “trier of fact” because the family law judge listens to the evidence and determines who should prevail, just as a jury would. In coming to that conclusion, judges often resolve factual disputes and determine which party is credible. Appellate courts generally defer to the trier of fact’s determination on factual matters since the trier of fact was the one in the courtroom and could assess credibility.