North Dakota Marriage Laws: What the State Constitution says…
Marriage is a personal relation arising out of a civil contract between one man and one woman to which the consent of the parties is essential. The marriage relation may be entered into, maintained, annulled, or dissolved only as provided by law. A spouse refers only to a person of the opposite sex who is a husband or a wife.
N.D. Stat. 14 03 01
Source: North Dakota State Constitution