The exclusion of a transgender woman from a female-only app constituted unlawful discrimination due to gender identity, according to a landmark Federal Court ruling.

Roxanne Tickle downloaded the Giggle for Girls social networking platform, which was designed to be an "online refuge" for women, in February 2021.

Users provided a selfie to be assessed by artificial intelligence software to verify they were a woman.

Ms Tickle's photo was accepted, but later that year her account was restricted after a manual override.

The court case she initiated is the first to claim discrimination on the basis of gender identity since changes to the Sex Discrimination Act in 2013.

Lawyers for the app's chief executive officer Sall Grover, who was named as a respondent, denied discriminatory conduct.

They invoked a carve out of sex discrimination law, claiming the app was a special measure designed to achieve substantive equality between men and women.

Justice Robert Bromwich today found there had been indirect gender identity discrimination against Ms Tickle.

The judge ordered that Ms Tickle be paid $10,000 in compensation, plus costs.

The judge found a claim of direct discrimination failed, however the successful claim of indirect discrimination was based on a condition being imposed for the use of the Giggle app that Ms Tickle was required to have the appearance of a cisgender woman.

The court previously heard Ms Tickle has lived as a woman since 2017, had a birth certificate reissued in 2018 to reflect a name change and stating her gender as female, and underwent gender affirming surgery in 2019.

"Up until this instance, everybody has treated me as a woman," she said during her evidence.

Unchangeable sex argument failed, judge says

Ms Tickle's counsel, Georgina Costello KC, said the caselaw made it clear that sex and gender and man and woman were not binary categories.

She argued it was not purely a biological question but partly psychological and partly social.

Reading out a summary of his decision today, Justice Bromwich said the defendants considered sex to mean the sex of a person at birth, which they consider to be unchangeable.

"These arguments failed because the view propounded by the respondents conflicted with a long history of cases decided by courts going back over 30 years," he said.

Ms Costello had also dismissed the argument about the carve out as being part of a series of "artificial, after-the-fact justifications" for discrimination.

Ms Grover's counsel Bridie Nolan argued sex is biological and gender was a social construct, disputing that Ms Tickle had the "psychology of a woman".

She told the court her client felt "harassed and intimidated" by Ms Tickle's efforts to contact her about the Giggle account, including eight unanswered emails before attempted phone contact.

Apology would be made 'through clenched teeth'

The app was intended to be a "corner of the internet" where women could "have refuge away from males", Ms Nolan said, and its creators had "absolutely no idea that males could be considered to be women".

Ms Tickle had also sought orders for a written apology, but Justice Bromwich declined to make those orders.

"It is plain that any apology given by Ms Grover, and any apology given by her on behalf of Giggle, would be through clenched teeth and utterly devoid of sincerity," he said.

Ms Tickle's legal team said she suffered significant distress, hurt and humiliation.

They claimed damages had been aggravated by Ms Grover's refusal to apologise and her "public vilification" of Ms Tickle, including comments which "consistently misgender[ed]" Ms Tickle.

The court also heard offensive merchandise was sold by a third party to raise funds for Ms Grover's legal bills.

'All women are protected from discrimination'

Outside court, Ms Tickle said the court case had "stolen" the last three years of her life.

She spoke of being targeted by hateful online commentary and seeing merchandise created to ridicule and mock her.

"There is so much hate and bile cast on trans and gender diverse people simply because of who we are," she said.

"Sometimes it's difficult to remember that not all people are like that."

Ms Tickle said the hate hadn't just affected her, but hurt many transgender and gender diverse people.

She hoped the outcome of the case would be "healing".

"The ruling shows that all women are protected from discrimination," she said.

Sex Discrimination Commissioner at the Australian Human Rights Commission Anna Cody said she was "happy" discrimination had been recognised in the judgement.

"We now know that ... you cannot discriminate on the basis of sexual orientation or gender identity," Dr Cody said.

"I think that this judgement sends the message that we want an inclusive society in which all can participate, and that includes trans people who have a range of sexual orientations.

"She [Ms Tickle] wanted the ability to connect with other women around cooking, around recipes, around housing ... to be able to connect with people."

As Ms Grover left court, she said the decision was what she expected.

"Unfortunately it is the judgement we anticipated and the fight for women's rights in Australia continues."

The app is currently not online.