At a hearing in August, Judge Adeane accepted the Crown's contention that Robinson inflicted the injuries on her baby daughter in one or both of two significant incidents during the same overnight drinking session.
Judge Adeane said a paediatrician's report stated the baby would inevitably suffer adverse cognitive impairment and learning difficulties, not only as a result of the immediate injuries related to that night.
It was also apparent she had previously suffered broken ribs and other fractures, he said.
It was appalling for a six-week-old to have obviously been a victim, not only of the actions that gave rise to these charges but also to some form of sustained abuse that was not possible (through lack of evidence) to sheet home.
The judge rejected a pre-sentence report writer's assessment that Robinson now posed a low risk of harm. Until she showed any insight, she was a real threat to any child in her care, he said.
The authorities obviously took the same view - they had since removed both children from her.The drinking session in which Liberty was injured began at the couple's home then shifted to an adjacent property.
Robinson's first attack on her partner occurred about 7.30pm when, intoxicated and accusing him of infidelity, she swung at Morgan but instead hit the baby girl who he was holding.
The baby's distress was apparent and audible to a friend who stepped in to lead Robinson away, he said. Nevertheless, the evening's activities continued after the baby was hit, Judge Adeane said.
The second incident occurred in the early hours of the morning, after Morgan had taken the children home to sleep. Robinson smashed her way into the house through a glass panel in the bottom of the locked door and again alleged infidelity.
She hoisted up a mattress from which Morgan had got up but on which the two children were still asleep. The boy was flipped on to the floor, the baby catapulted out of her sleeping pod.
As she fell to the floor, her head struck the wooden frame of a coffee table.Liberty's injuries were apparent just a few hours later. Others suggested the couple take her to a doctor.
But it was not until about five days later, when she had been suffering repeated spasms and fits, that the situation got so bad the pair finally sought medical help for her.
The baby was transferred to Starship Hospital.Counsel Adam Simperingham said Robinson had since attended various parenting courses. The charge of neglect was "just that".
There was nothing intentional in Robinson's lack of action - it was more brought about by alcohol and ignorance.
The recklessness she showed in relation to the injuring charge was likewise not intentional, even though the outcome for the baby girl was "terrible".
Crown counsel Jo Rielly said the pre-sentence report highlighted Robinson's still very limited insight into her behaviour, even after the court hearing.Despite having completed some parenting courses, Robinson still had significant rehabilitative needs, Mrs Rielly said.
Having contributed to two actual acts of violence against the child, Robinson was much more culpable than her partner. A five-year starting point was sought. Judge Adeane agreed such a starting point could be argued but said that "in safety" he would adopt a lesser four-year start, which included an uplift of one year for the reckless disregard.
There were no other factors that required any adjustment of the sentence. He told Robinson her offending "sat right on the boundary of disregard and deliberate intention".
Baby Liberty was born five weeks prematurely. Robinson admitted to her Plunket nurse she regularly consumed alcohol while pregnant.
