Haw. Rev. Stat. § 660-4: For prisoners, for trial or testimony.

Nothing in this chapter shall be construed to restrain the power of any court of record to issue a writ of habeas corpus ad respondendum, when necessary, to bring before it any prisoner for trial in any criminal cause, lawfully pending in the court, or a writ of habeas corpus ad testificandum, to bring in any prisoner to be examined as a witness in any action or proceeding, civil or criminal, pending in the court, when it thinks the personal attendance and examination of the witness is necessary for the attainment of justice. The writ may be issued for such purposes by any court of record in the exercise of a sound discretion, and with due regard to conflicting interests and liabilities, anything in this chapter to the contrary notwithstanding.