A transgender woman who stimulated lactation and fed her baby the liquid produced has been ordered by the Queensland Civil and Administrative Appeals Tribunal to provide details of the hormones involved and the composition of the substance.

The overturning on appeal of a previous QCAT ruling represents a win for former Australian Breastfeeding Association counsellor Jasmine Sussex, who is being sued for vilification by Jennifer Adrian Buckley over statements referring to Ms Buckley as a “man pretending to be a woman”, “a child abuser” and someone who adopted a “delusional queer theory take” on breastfeeding.

The decision, handed down late last week by senior QCAT members Ned Aughterson and Samantha Traves, set aside a January ruling by fellow QCAT member Peter Bridgman, finding he had made errors in law constituting a “substantial miscarriage of justice”.

Professor Aughterson and Ms Traves found Mr Bridgman had erred in deeming that the process involved in stimulating lactation in biologically male Ms Buckley, and the nature of the substance fed to the baby, were not relevant to the case.

Ms Buckley has been given a deadline of September 16 to provide particulars of “the ‘induction’ of lactation including whether the induction involved hormonal stimulation and, if so, what hormones, the source thereof and the process and extent by which the levels were decreased or increased; the composition of the substance which was lactated; and the precise source of secretion of the lactated material”.

She has publicly detailed her story of having used hormones to induce lactation under the supervision of endocrinologist Naomi Achong in 2019, in order to feed the baby, of whom she is the biological father, for less than a week soon after the child’s birth.

Ms Buckley’s vilification case against Ms Sussex over online comments made by the former breastfeeding counsellor between 2021 and 2023 has been working its way through QCAT since the trans woman complained to the Queensland Human Rights Commission in late 2023.

In seeking to defend herself, Ms Sussex – represented by the high-profile freedom of speech advocate Tony Morris KC, who is being briefed by the Christian-aligned Human Rights Law Alliance – sought details relating to Ms Buckley’s claim that she had “induced lactation under the supervision and with the knowledge of medical professionals”. The particulars sought by Ms Sussex relate to the nature and provider of the “medical supervision”, how lactation was induced, how it constituted “lactation”, and how it was determined the fluid was “breast milk”.

In his now-overturned January decision, Mr Bridgman found those matters had “no bearing” on whether Ms Sussex had “incited hatred” of Ms Buckley “or a class of persons”, namely transgender women, and were therefore not relevant to the case.

In their decision to allow Ms Sussex’s appeal, Professor Aughterson and Ms Traves found “a reasonably arguable case of error” in Mr Bridgman’s ruling, and that “it would cause a substantial injustice to (Ms Sussex) were the matter to proceed absent the particulars requested given their relevance to the outcome of the complaint”.

The appeal judges found Mr Bridgman had given “no consideration” to the issue of whether the information sought was relevant to whether Ms Sussex’s comments were made “reasonably and in good faith … for public interest purposes”, as is permitted under the Queensland Anti-Discrimination Act.

“It is that issue which is central to (Ms Sussex)’s application for a notice to produce,” they found.

“It is (Ms Sussex’s) submission that the capacity of a transgender woman to produce milk and breastfeed is contentious and, in that context, a relevant issue in the public interest is whether the respondent was … able to do so.”

The judges cited evidence heard in the case from a medical doctor and bioethicist that “no evidence-based protocol to support the process of inducing lactation in a transgender woman (biological male who has transitioned to live as a woman) has yet been published in the academic literature”, and that “no longitudinal research exists regarding whether it is nutritionally adequate nor whether there are any negative outcomes for the child”.

Another expert witness, a registered pediatrician, is cited as having made reference to “the risks associated with taking ­‘secretion-inducing drugs’, including for the infant”.

Ms Sussex said she was “relieved” by the tribunal’s decision.

“There is no scientific foundation for men trying to induce lactation. The tribunal has agreed it’s a relevant issue for the case,” she said.

“Inducing male lactation is experimental, untested and unproven. I don’t have a personal issue with (Ms Buckley), but I want to protect mums and babies and their sole right to breastfeed and receive maternal breastmilk.”

Ms Buckley, who is being represented by Kathleen Foley SC, was contacted for comment.