Trier of fact refers to a judge or jury in a court case. In a jury trial, the jury decides issues of fact while the judge makes legal rulings as to what evidence will be heard by the jury and what the law applicable to the case will be. In cases where there is no jury, the judge serves to decide both questions of fact and questions of law. In an administrative hearing, the trier of fact may be an administrative law judge, a board, commission or referee.
In an appeal of a decision from a lower court, the appeals court generally does not decide questions of fact, but only reviews the lower decision for legal errors.
