Haw. Rev. Stat. § 572B-2: Eligibility to enter into a civil union.

A person shall be eligible to enter into a civil union only if the person is:

(1) Not a partner in another civil union or a spouse in a marriage;

(2) At least eighteen years of age; and

(3) Not related to the other proposed partner in the civil union, as provided in section 572B‑3.