Haw. Code R. § 3-161-42
At any time before the filing of the hearings officer's recommended decision, or if the hearing has been held before the commission, then before the commission's final decision, the hearings officer or the commission, sua sponte or upon motion for good cause shown, may reopen a hearing for the purpose of taking further evidence, and shall do so in writing with a statement of reasons therefor. The commission, sua sponte, shall have the discretion to remand a petition or proceeding to the hearings officer for the purpose of taking further evidence. The reopening or remanding shall be at the sole discretion of the hearings officer or the commission. Further evidence may be taken either through oral hearing or by certification of questions to the parties.
Haw. Code R. § 3-161-42