A few hours ago a court in Australia eliminated gender as a binary proposition. The New South Wales court of appeals rejected a lower court's ruling that Australians must check either "male" or "female" on official documents requesting their gender. The ruling centered on the case of Norrie, a Sydney resident who does not use a last name. Today's Sydney Morning Herald reports that Norrie had sought the right to identify as neither male nor female in official records. The high court decision allows Norrie to respond "sex not specified."
The ruling is being described this morning as legal affirmation of an expanded definition of gender. Allowing a "none of the above" response is not the same thing as identifying a third option (or fourth, or fifth). That's presumably yet to be argued, should someone decide to force the issue legally.
The case has implications for families with children displaying both female and male characteristics, which the Intersex Society of North America estimates occurs in 1-1,500 to 1-2,000 births.
Among the civil procedures the ruling may affect are death announcements and, indeed, marriages.