A Sydneysider’s High Court win to be recognised neither as man nor woman could have wide ramifications, a lawyer says.

The High Court has backed a case of gender neutral recognition in a ruling that could have ramifications across Australia.

Sydney resident Norrie, 52, has won a long-running legal battle against NSW’s Registry of Births, Deaths and Marriages to be granted non-specific gender status.

Norrie, who goes by one name, was born male and underwent gender reassignment in 1989. But Norrie stopped taking hormones after surgery and no longer identifies as male or female.

In a world first in 2010, Norrie was given gender neutral status, but this was withdrawn months later by the NSW government, sparking a string of appeals and counter appeals which reached the High Court.

A unanimous judgment handed down on Wednesday found in Norrie’s favour.

“The act does not require that people who, having undergone a sex affirmation procedure … must be registered, inaccurately, as one or the other,” the court found.

Despite its ruling, the court repeatedly refers to Norrie as “she” and “her” in its judgment, citing that Norrie’s legal representatives used the terms in submissions.

Norrie’s lawyer, Scott McDonald, described the case outcome as a “persuasive authority” for other jurisdictions.

“It’ll be binding on the states that have identical or similar legislation,” he told reporters.

And for states such as Western Australia, with very different legislation, the judgment has sent a message the High Court doesn’t think gender is limited to male and female.

The court was asked to consider whether “non-specific” can be included as a third gender category under the Registry’s Act.

Lawyers for the Registry argued unacceptable confusion would flow from the acceptance of more than two gender categories, and that the purpose of a reassignment procedure is to assist a person to be considered a member of the opposite sex.

But counsel for Norrie said it is the register’s purpose to record the truth.

“Norrie’s sex remained ambiguous so that it would be to record misinformation in the register to classify her as male or female,” a judgment summary reads.

For Norrie, Wednesday’s ruling was “very exciting”.

“Many other people let me know they wanted (to identify as non-specific) in Australia and indeed around the world,” Norrie told reporters in Sydney.

The Human Rights Law Centre said it was important that identity documents such as birth certificates give equal recognition to gender diverse people.

“It’s essential that our legal systems accurately reflect and accommodate the reality of sex and gender diversity that exists in our society,” spokeswoman Anna Brown said.

Community support group A Gender Agenda spokesman Sam Rutherford said all states and territories would have to pay attention to the judgment.

Norrie’s application for non-specific status should now be reconsidered by the Registry in accordance with the court’s finding, the judgment said.

The Registry must pay Norrie’s costs of the High Court appeal.