Haw. Rev. Stat. § 806-61: Waiver of jury.

The defendant in any criminal case may, with the consent of the court, waive the right to a trial by jury either by written consent filed in court or by oral consent in open court entered on the minutes. Any case in which a trial by jury is waived may be tried by the court without a jury both as to the facts and the law, and when the trial has been had there shall be no further trial upon the facts, except upon the granting of a new trial according to law.