Haw. Rev. Stat. § 560:3-713: Sale, encumbrance, or transaction involving conflict of interest; voidable; exceptions.

Any sale or encumbrance to the personal representative, the personal representative's spouse or reciprocal beneficiary, agent, or attorney, or any corporation or trust in which the personal representative has a substantial beneficial interest, or any transaction which is affected by a substantial conflict of interest on the part of the personal representative, is voidable by any person interested in the estate except one who has consented after fair disclosure, unless:

(1) The will or a contract entered into by the decedent expressly authorized the transaction; or

(2) The transaction is approved by the court after notice to interested persons.