Shari-Lea Hitchcock, the mother of the cardboard king's fourth child, was found guilty on Wednesday of three offences and placed on good behaviour bonds in Downing Centre Local Court over the March 2016 incident.

A dishevelled Hitchcock, now 49, was stumbling in her high-heel boots through traffic in Oxford Street, Woollahra, before she lashed out at police and a well-meaning widow who had stopped to help her.

Magistrate Jennifer Atkinson said Hitchcock was hanging onto a rail when Jan Haswell tried to guide her off the road and then leaned down to pick up the socialite's fallen glasses.

But Hitchcock instead assaulted the widow and then, when police arrived to take her away, shouted "I'm not f***ing going anywhere", the magistrate said.

Unable to tell officers where she lived and trying to stop an officer taking notes, the socialite who was "in significant need of protection" was arrested.

She soon struggled free, kicked a female officer in the chest before biting her on the leg during a struggle.

"It's apparent from all the evidence, she was doing all she could to break free," Ms Atkinson said.

Hitchcock pleaded not guilty to common assault, assaulting police and resisting arrest.

Her lawyers, who contested the legality of her arrest and tried to discredit the widow's evidence, asked for no conviction to be recorded and argued the incident wouldn't have happened had she been allowed to take a taxi home.

"It's a series of unfortunate events because Ms Hitchcock was just trying to get home," defence lawyer Bryan Wrench said on Wednesday.

"She was so intoxicated that I'm not sure she would have got home," Ms Atkinson said.

Ms Atkinson said she couldn't find any remorse or contrition as Hitchcock had never given her account of the day.

She placed Hitchcock on a two-year bond for biting and two 12-month bonds for the lesser charges.

The socialite had an 18-year affair and a daughter with Pratt, the Visy Industries tycoon who died in 2009 worth an estimated $4 billion.

The Australian Financial Review in April named Pratt's successor, son Anthony, as the nation's richest person, worth an estimated $12.9 billion.

Hitchcock reached a settlement with Pratt's estate in 2015.

Australian Associated Press