A Sydney court ruling which allows a person to be registered as gender-neutral could potentially have legal implications around Australia.

In the first case of its kind in Australia, the New South Wales Court of Appeal yesterday ruled that a person does not have to be registered as male or female.

Norrie, who goes by only one name and was born as a male, underwent sexual reassignment surgery in 1989.

Three years ago the Registry of Births, Deaths and Marriages issued a certificate showing Norrie's sex as not specified.

But the certificate was revoked in 2010 in a move backed by the Administrative Decisions Tribunal, finding a gender must be specified.

Norrie appealed against the decision, which was upheld yesterday.

The matter is being sent back to the tribunal to decide on a gender-neutral designation.

Norrie has welcomed the news, and says the decision shows the law can be fair.

"It's great that the law has done the right thing and been seen to be fair and just for everyone, not just the majority," Norrie said.

Norrie's solicitor, Emily Christie, says the ruling has wider ramifications for gender identification in Australia.

"This is the first time that we've had any court of law in Australia saying that sex could potentially mean something other than male or female," she said.

"We're hoping that this decision will then be taken on in a broader context both for courts of law - and also for government agencies."

Ms Christie says the decision is incredibly important.

"It means that they're recognised not only in births, deaths and marriages, but it has flow-on effects to all other legislation and all legal interactions in New South Wales and potentially around Australia," she said.

The News South Wales Government is currently assessing the implications of the successful appeal.

A spokesman for Attorney-General Greg Smith says the Government is getting advice on the ruling.