A man who donated sperm to conceive a child with a friend and went on to be involved in his daughter's life is legally her father, Australia's highest court has ruled.
The long-running family law dispute, between Robert Masson and couple Susan and Margaret Parsons, was resolved in a ruling on Wednesday that prevents the Parsons from relocating to New Zealand with the girl and her younger sister.
All names are pseudonyms ordered by the court.
Masson and Susan Parsons had known each other for more than 15 years when he provided sperm for her to conceive a child.
He was named as the father on the birth certificate and told the court he had always intended to take an active role in his daughter's life, and did so as she grew up.
The girl and her younger sister — who was conceived using anonymous donor sperm and is the legal daughter of Susan and Margaret — both live with the Parsons, who are married.
The girls spend time with Masson, who they call "Daddy", and his male partner.
The arrangement worked well until 2015, when Susan and Margaret wanted to move to New Zealand and Masson filed a lawsuit in the Family Court to stop them.
Family Court justice Margaret Cleary found in 2017 that Masson was the legal father of his daughter and ordered that the Parsons could not move with the girls to New Zealand.
Cleary said the lawsuit had "battered" the long standing friendship between Masson and Susan Parsons, causing "interpersonal bitterness" and accusations.
"There are mutual feelings of betrayal. Truth has been sacrificed at times to loyalty," she said.
"All this has been skilfully and sensitively concealed by the three parties and other involved adults to shield the two children and to preserve the loving feelings both of them have for all the important people in their lives."
The decision was overturned on appeal to the full Family Court, which last year ruled Masson was presumed not to be the girl's legal parent under New South Wales state law, which dictates a man who donates sperm is not the father unless he is married to or in a de facto relationship with the mother at the time.
The case then went to the High Court, which considered whether state or federal law should be applied in the case.
On Wednesday morning a majority of justices ruled that Cleary's original decision declaring Masson was the legal parent and stopping the move was the correct one.
The Parsons argued that the court should find the ordinary English meaning of "parent" excludes somebody who is a sperm donor.
The High Court rejected this, saying that what constitutes a "parent" has to be determined based on the situation at hand.
"To characterise the biological father of a child as a 'sperm donor' suggests that the man in question has relevantly done no more than provide his semen to facilitate an artificial conception procedure on the basis of an express or implied understanding that he is thereafter to have nothing to do with any child born as a result of the procedure," the judgement reads.
"Those are not the facts of this case."
The justices went on to note that it was an undisputed finding in the case that Masson had provided sperm with the understanding he would be the girl's father — including being listed on her birth certificate and supporting and caring for her — and that labelling him a "sperm donor" would ignore the majority of the facts.
It was unnecessary for the court to decide more generally if a man who just provides sperm would be a legal parent, the judgement said.
The original orders made by Cleary ruled that the Parsons had shared parental responsibility for the girls but must consult Masson when it came to making long term decisions.
It also restrained the couple from moving to New Zealand without written permission from Masson.