A trier of fact is the person or group of persons in a trial who make findings of fact as opposed to rulings of law. A trial is, in the most general sense, a test, usually a test to see whether something does or does not meet a given standard. ... Law (a loanword from Old Norse lag), in politics and jurisprudence, is a set of rules or norms of conduct which mandate, proscribe or permit specified relationships among people and organizations, provide methods for ensuring the impartial treatment of such people, and provide punishments for those who do not follow...

In a jury trial, the jury is the trier of fact. The jury finds the facts and applies them to the law it is instructed by the judge to use in order to reach its verdict. Thus, in a jury trial, the findings of fact are made by the jury while the judge makes legal rulings as to what evidence will be heard by the jury and what the law will be that governs the case. The jury is supposed to strictly follow the law as given by the judge, but it does not always do so. In some cases this amounts to jury nullification, i.e. the jury effectively re-writing the law or blatantly ignoring it in a particular case. This article is confusing for some readers, and needs to be edited for clarity. ... A judge or justice is an appointed or elected official who presides over a court. ... Jury nullification is a jurys right to deliver a not-guilty verdict even where such a verdict clearly conflicts with the letter of the law. ...

In a "bench trial," or non-jury trial, a judge is the trier of fact. In a bench trial, the judge makes both findings of fact and rulings of law. A bench trial in the U.S. is a trial before a judge in which the defendant has waived his/her right to a jury trial. ...

In Anglo-american based legal systems, there is a strong reluctance to change findings of fact made by a jury. This principle is enshrined in the Seventh Amendment to the United States Constitution, which provides that "...no fact tried by a jury, shall be otherwise re-examined in any Court of the United States, than according to the rules of the common law." The Seventh Amendment to the United States Constitution, which is part of the Bill of Rights, guarantees juries in certain civil trials. ...