The former state Liberal leader is seeking to overturn findings she breached public trust by failing to disclose her covert relationship with disgraced Liberal MP Daryl Maguire.
The NSW Independent Commission Against Corruption found in June that this "serious corrupt conduct" included Ms Berejiklian sitting on a cabinet committee considering multimillion-dollar funding arrangements pushed by Maguire to benefit his Wagga Wagga electorate.
On the second day of a hearing in the NSW Court of Appeal on Tuesday, ICAC's barrister Stephen Free SC argued there was a "rational foundation" for finding Ms Berejiklian had been influenced by her desire to maintain or advance her relationship with Maguire.
Mr Free described Maguire as a "special kind of serial pest" in his lobbying with the former premier.
"He was agitating for his interests in his electorate but taking advantage of a particular emotional relationship that existed only as between them," he told three appeal judges.
There was evidence of Maguire's "emotional hold" on Berejiklian at the time, including his insecurity and disquiet about a lack of progress on certain proposals and his desire to "be the boss", the court heard.
While Ms Berijiklian claimed she treated Maguire like any other MP, Mr Free said her vision for their future, which included marriage, children and life after politics, meant she had an interest with him that was different to her connection to others.
Between 2016 and 2018, as treasurer and then premier, Ms Berejiklian was involved in approving or supporting allocations of $5.5 million for the Wagga-based Australian Clay Target Association and $10 million for the Riverina Conservatorium of Music.
Admitting that others on the cabinet committee also approved Maguire's proposals, Mr Free said this did not mean Ms Berejiklian herself was not affected by her personal attachment when making a final decision.
"She was influenced by not just her assessment of the merits of the proposals but a desire to maintain her relationship with Mr Maguire," the barrister said.
"The commission being alive to Ms Berejiklian's protestations on these topics simply didn't accept as a matter of fact that she was not influenced."
Gladys Berejiklian failed to report her covert liaison with Liberal MP Daryl Maguire. (Bianca De Marchi/AAP PHOTOS)
Ms Berijiklian's barrister Bret Walker SC previously argued ICAC made several "defects of reasoning" and errors of law in making its findings.
There was no evidence Ms Berejiklian's relationship with Maguire influenced her or created an actual conflict of interest, he said.
Mr Walker also submitted the report was "delivered in excess of jurisdiction" by former judge Ruth McColl, who was appointed assistant commissioner to help with the inquiry.
While Ms McColl's appointment as assistant commissioner expired in October 2022, she was kept on as a consultant for another eight months before the report was published.
Ms Berejiklian claims Ms McColl was not authorised to publish any report given her status as a "consultant" and not a commissioner.
But Mr Free defended the report, saying Ms McColl's role was to preside over hearings and to deliver a draft report to the commission.
The final report was released by the chief commissioner, who had authority to do so, and not by Ms McColl, the court heard.
The hearing continues.