Haw. Rev. Stat. § 88-1.2

For the purposes of this chapter, the terms "married", "marriage", "marital", "husband", "wife", or similar spousal terms shall include civil union partners and civil unions under chapter 572B, unless recognition of a civil union as a marriage conflicts with the requirements for the system to be a tax-qualified plan under section 401(a) of the Internal Revenue Code of 1986, as amended.