On the trial of any issue, matter or question, or on an inquiry arising in any action or proceeding in any court or before any person having authority to hear, receive, and examine evidence, any person who happens to be present, and who by virtue of this chapter is competent to give evidence may be called and required to give evidence and to produce any document. If any such person when called and required as aforesaid, does not appear and give evidence and, if then able so to do, produce the document, the person shall be subject to the same proceedings and liabilities as if the person had been duly served with a writ of subpoena ad testificandum or duces tecum.
HRS § 621-5
Power of court itself to call witness.24 Haw. 689.