An Adelaide lawyer has won a $750,000 defamation payout against a woman who gave his firm a bad review on Google.

Key points: Isabel Lok wrote a bad online review about Adelaide lawyer Gordon Cheng's firm

Isabel Lok wrote a bad online review about Adelaide lawyer Gordon Cheng's firm Mr Cheng said he lost 80 per cent of his clients and $631,000 in income

Mr Cheng said he lost 80 per cent of his clients and $631,000 in income A judge ordered Ms Lok pay him $750,000 in damages

The woman, Isabel Lok, was never a client of barrister Gordon Cheng, according to his evidence in the South Australian Supreme Court.

But she posted a one-star rating of his business on Google in October 2018 in English and Chinese, along with an extensive negative review.

Mr Cheng, 66, was born in Hong Kong and most of his clients come from Adelaide's Chinese community, or from China and Hong Kong, the court heard.

He told the court he lost about 80 per cent of his clients between the bad review and when a former client made him aware of it in February 2019.

He said the post caused him "significant distress, anxiety and financial hardship".

In March 2019 he issued a concerns notice to Ms Lok and made a complaint to Google.

Rather than deleting the review, the court heard Ms Lok changed her name on the review to Bel, then Cindy and finally Peter, the name of her father, who owns a restaurant in Adelaide's Chinatown.

He denied any connection with the review, according to Mr Cheng.

Negative review removed but more added

Google removed the review on April 30, 2019, but Ms Lok later posted similar reviews under two more names.

Ms Lok did not appear to defend herself in the Supreme Court. ( ABC News: Eugene Boisvert )

In one of them, she denied Mr Cheng's claim that she was never his client.

"Your database is incomplete. I did consult with you," she wrote.

She did not reply to a summons served on her or Mr Cheng's statement of claim, and never appeared in court in person or represented by a lawyer.

She could not be reached by ABC News.

Mr Cheng said it was a "very fair judgment".

"I serve the community, I do lots of pro bono work and as far as I'm concerned I don't know why I deserve this," he said.

"Legislation should be changed to stop such things happening in the future otherwise no matter how hard you work it can easily be destroyed by social media in a couple of months or a couple of days."

Google data presented to the court showed the review was viewed about 800 times a month while it was up.

Every other Google review of Mr Cheng's business gave it five stars.

Lawyer also suffered anxiety and depression

Mr Cheng's accountant, Karen Phu, estimated his total loss of income to be $631,229 from November 2018 to January 2020.

She estimated the damage to the value of his business at $296,146.

Mr Cheng also claimed general and aggravated damages of $200,000.

"[Mr Cheng] says that he has suffered significant distress as a result of [Ms Lok]'s actions," Judge Katrina Bochner wrote in her decision handed down yesterday.

"He suffers anxiety every time he turns on his computer to check if there are any new posts from the defendant.

"The financial losses caused by the publication have caused him significant distress, anxiety and financial hardship.

"In April 2019, [Mr Cheng] was diagnosed with depression and started taking anti-depressant medication.

"He has never met [Ms Lok] or acted for her. As a result, there can be no question that [Ms Lok] was not acting in good faith.

"The only conclusion that can be drawn is that her intention was to destroy [Mr Cheng]'s livelihood, and cause him distress, anxiety and financial hardship."

No apology from defendant

Judge Bochner ordered Ms Lok pay Mr Cheng $750,000 in compensation.

She said his business had recovered faster than expected after the review was taken down, and it was unclear whether his depression was solely from his loss of business.

She said Ms Lok had never apologised or offered any compensation.

"Indeed, the defendant's only response to this matter was to change the name of the person posting the review and to post a further review," Judge Bochner said.

Ms Lok will also have to pay costs.