Haw. Rev. Stat. § 381-6: Powers of board; evidence, witnesses; process by mail, etc.

The emergency board may hold hearings at any place within the State, subpoena witnesses and compel their attendance, compel the production of books and papers, administer oaths, take testimony, and receive evidence.

In case of contumacy or refusal to obey a subpoena issued to any person, the circuit court of any judicial circuit within the jurisdiction of which the inquiry is carried on, upon application by the board, shall have jurisdiction to issue an order requiring such person to appear before the board, to compel the production of papers, to produce evidence, or to give testimony touching the matter in question. Failure to obey any such order may be punished by the court as a contempt thereof.

Process and papers of the board may be served either personally or by registered mail or by radiogram or by leaving a copy thereof at the principal office or place of business of the person to be served. Return by the individual serving the same setting forth the manner of the service, return post office receipt or radiogram receipt shall be proof of service of the same.