Jie Shao flew from China to Australia in August 2017 to perform breast enhancement on Jean Huang, who operated the Medi Beauty Clinic in the inner-Sydney suburb of Chippendale.
Ms Huang died after the procedure, in which hyaluronic acid was injected into her breasts as filler.
"That was a procedure which was not legally allowed in Australia at the time," the crown prosecutor told a jury panel as Shao's criminal case began on Thursday.
A local anaesthetic lidocaine was then administered after Ms Huang expressed concerns about how painful the procedure would be, potential jurors in Sydney's Downing Centre District Court heard.
Shao has pleaded not guilty to one charge of manslaughter for the unlawful killing of Ms Huang in September 1, 2017.
However, she pleaded guilty to injuring Ms Huang by administering a poison on August 31, 2017.
The crown prosecutor told potential jurors that the cause of death was brain injury due to an overdose of lidocaine.
Shao told Ms Huang she was a doctor despite not being registered in either China or Australia, the court heard.
The trial continues.
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