A judge is an official who presides over court proceedings, either alone or as part of a panel of judges. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions. The judge is supposed to conduct the trial impartially and in an open court. The judge hears all the witnesses and any other evidence presented by the parties of the case, assesses the credibility and arguments of the parties, and then issues a ruling on the matter at hand based on his or her interpretation of the law and his or her own personal judgment. In some jurisdictions, the judge's powers may be shared with a jury. In inquisitorial systems of criminal investigation, a judge might also be an examining magistrate.