TV cook Nigella Lawson was described as a "habitual criminal" in a London court on Wednesday.
Italian sisters Francesca and Elisabetta Grillo are due to go on trial accused of using a company credit card to buy themselves designer handbags and flights while working as personal assistants to Lawson and Charles Saatchi.
But lawyers for the defendants argued today that the case should not go ahead due to the "manipulation of the court process" by the TV cook and the millionaire art dealer, who had a high-profile divorce earlier this year.
On Tuesday, Isleworth Crown Court in west London heard that Saatchi alleges that Lawson was so high on drugs that she was unaware of what she had or had not permitted the sisters to spend money on.
After hearing submissions from Anthony Metzer QC, defending Elisabetta Grillo, 41, and Karina Arden, defending Francesca, 35, Judge Robin Johnson ruled that the trial should go ahead.
"I consider, with the right rulings and the ability to monitor the process of the court during the process of the trial, a fair trial can be achieved and therefore I have refused this application," he said.
Earlier Mr Metzer argued that the case should be dropped as Mr Saatchi and Ms Lawson were at "loggerheads" and the alleged drug use damaged the TV cook's "credibility as an honest witness".
He told the court: "The defendants' case is that Nigella Lawson lied to her ex-husband about her drug use and about the expenditure that was incurred by the defendants, both expressly and implicitly, because she was fearful of Mr Saatchi's reaction if he knew about the extent of the expenditure and drug use.
"There was a culture of secrecy within Nigella Lawson's marriage."
He argued that the defendants will not receive a fair trial "as there has been a manipulation of the court process by the two main prosecution witnesses in this case".
He said that if it did go ahead, "it's a convenient forum for Mr Saatchi and Miss Lawson to rehearse disputed issues between them ... in the criminal courts where, of course, the possibility of libel is not possible".
"If Mr Saatchi is telling the truth, then Miss Lawson is a habitual criminal."