Erin Patterson’s lawyers took her case to the Court of Appeal in Melbourne, reportedly arguing she had suffered a miscarriage of justice.
But the court refused to allow her attempt and she now has until 27 November to make her case to the country’s high court.
Patterson, who appeared in court on Friday via videolink from prison, was sentenced in September 2025 to life behind bars with a minimum of 33 years.
She was found guilty in July 2025 of the murders of her parents-in-law, Don and Gail Patterson, and her aunt-in-law Heather Wilkinson, who she had invited for lunch at her home.
Her estranged husband Simon Patterson, with whom she has two children, was also invited to the meal and initially accepted but later declined, a court heard.
Erin Patterson’s lawyers argued that among the grounds for appeal was that the cross-examination by prosecutor Nanette Rogers of Patterson over five days was “unfair and oppressive”.
Also, the trial judge Christopher Bale had caused “unfair prejudice” by allowing evidence from her Facebook “friends”, the defence team argued.
Patterson insisted she added death cap mushrooms to the meals accidentally.
The victims, who also included Mrs Wilkinson’s husband, Ian Wilkinson, had been invited to lunch at Patterson’s home in Leongatha, Victoria, on 29 July 2023.
All four fell ill after eating the meal, which also included mashed potatoes and green beans, a court was told.
Heather Wilkinson and Gail Patterson died on Friday 4 August 2023, while Don Patterson died a day later.
Erin Patterson was also convicted of the attempted murder of Ian Wilkinson, who survived after spending weeks in hospital.
Mr Wilkinson said he was left feeling “half alive” after the ordeal.
