Haw. Code R. § 20-10-17
At no time after the filing of the written request for a contested case hearing shall any hearing officer, the president or the president's designee who renders a decision in an administrative contested case, or any other person who is likely to advise these officials in the decision on the contested case, discuss ex parte any issue of fact or the merits of the contested case with any interested person not performing a decisionmaking function, except by giving notice to both the debtor and claimant providing an opportunity for all parties to participate in the discussion. This prohibition shall not apply to consultations required for the disposition of ex parte matters authorized by law or to consultations with the decisionmakers' legal counsel covered by the attorneyclient privilege.
Haw. Code R. § 20-10-17