Prosecutor Justin Lewis told the court that doctors found that the symptoms were entirely related to the child’s malnourishment and that the cerebral palsy – a debilitating disability from which the baby now sufferers – came from the malnutrition.
Mr Lewis said doctors commented that the condition of the child was often found in newborns in countries experiencing famine.
County Court judge Claire Quin heard on Friday that the parents had clashed with healthcare professionals, who repeatedly told them a plant-based diet was inadvisable for a baby.
The parents, who appeared remotely via videolink, listened intently to proceedings as both of their lawyers asked Judge Quin to spare them jail.
The pair eventually disengaged from healthcare services altogether, feeling as though mainstream medicine “did not understand them”.
The two have since had a second child, but have separated.
Barrister Jane Warren said the mother was a more “passive” parent, and that an uneven power imbalance meant the father was making almost all of the decisions about their young baby’s the nutrition.
But barrister for the father, Julia Munster, rejected this.
Ms Munster told the court the father, who was the primary adherent to the vegan diet, did not trust orthodox medical science and sought nutritional substitutes from overseas.
Judge Quin accepted that the couple had been told by medical professionals that the diet they had planned for their daughter was “not going to work for their infant”.
“These parents, they weren’t 19 or 20 years old, they were in their early 30s,” Judge Quin said.
“They’re told that what they’re contemplating isn’t going to work for their infant, but they continue to do it.”
The child, who is now three, lives with her mother and requires several allied health professionals for her care.
The court suppressed the identities of the parents after lawyers successfully argued that publicising their names may affect their reputation among parents in their area, given they are members of children’s groups.
Mr Lewis was emotional as he read the investigator’s summary of evidence against the pair.
Mr Lewis told the court that, upon struggling to find appropriate vegan formula, the father made his own out of dates, fruit and other vegetables. He has now adjusted his own diet and eats meat.
Mr Lewis also detailed a clash the parents had with a nurse who, concerned with the health of their child, considered escalating the matter as she had not heard from the parents for an extended period.
The parents responded to her concerned emails and texts with a threat, saying they were considering lodging a complaint against her and her emails were “uncalled for” and that they were “interpreted as threatening” towards the pair.
Mr Lewis also described text message exchanges showing how the parents mocked a media report which was critical of parents who put their infants on an all-vegan diet.
Ms Munster said her client’s moral culpability was “towards the lower range of seriousness” and that he had experienced depression and anxiety in the wake of his child’s illness.
They will be sentenced later this month
David Estcourt is a court and general news reporter at The Age.