The mushroom killer, whose fatal July 2023 lunch devastated her ex's family and shocked people across the globe, has sought to overturn a guilty finding that led to her life sentence.
Prosecutors meanwhile have called for Patterson to have a look at parole.
The Victorian Court of Appeal will hand down its long-awaited decision on Friday morning.
As well as potentially ordering a retrial, the decision could pose issues for the numerous podcasts and a 2027 small-screen mini-series.
Patterson is not expected to face the judges in person, instead choosing to watch remotely from Dame Phyllis Frost Centre, the prison where she is housed in Melbourne's west.
The 52-year-old claims she suffered a miscarriage of justice when a jury found her guilty of three counts of murder and one count of attempted murder.
Jurors believed she deliberately served beef Wellingtons laced with death cap mushrooms to her former in-laws Don and Gail Patterson, 70, and Gail's sister Heather Wilkinson, 66.
The three guests died after the July 2023 lunch at Patterson's Leongatha home, in regional Victoria, while Heather's husband Ian fell seriously ill from the meal but survived.
At her appeal hearing in August, Patterson's lawyers argued she suffered a substantial miscarriage of justice during her high-profile trial and her convictions should be quashed.
Barrister Richard Edney pointed to the "catastrophic" decision to sequester jurors in the same hotel as the lead detective and prosecution team during their verdict deliberations.
Patterson had also been "forced" to give evidence during her trial to show she always had an interest in foraging for mushrooms, the defence said.
The cross-examination from the prosecutor had been unfair and oppressive, and the prosecution closing address was also "problematic", Mr Edney argued.
But Victoria's top prosecutor said there was no substance to the arguments and Patterson instead should be facing a longer sentence for her crimes.
Patterson was jailed for life but given a chance at freedom with a 33-year non-parole period.
Brendan Kissane KC argued the sentence was manifestly inadequate and Patterson should not be allowed to walk from prison.
Justices Stephen McLeish, Lesley Taylor and Peter Kidd have spent just over two months considering the arguments.
There are four possible outcomes for Patterson's appeal.
She will either be granted leave to appeal or refused leave to appeal, which is the first hurdle she has to clear.
If she is granted leave, the court must then decide whether to uphold or refuse her appeal.
If her appeal is upheld, she could be granted a retrial or a complete acquittal.
The court will not need to decide on the prosecution's appeal if Patterson is successful.
But if Patterson loses, the court has two options.
It can dismiss the prosecution appeal, leaving the sentence unchanged.
The court could alternatively grant the prosecution appeal and re-sentence Patterson, increasing her 33-year non-parole period.
The judges will hand down their decision at 10am AEDT on Friday.
It comes just days after Paramount+ and Ten announced a six-episode drama series about the Patterson case, titled 'Mushroom Murders: There's More to Unearth'.
Emmy-nominated actor Melanie Lynskey has been cast to play the murderer in the series, which is slated to be released in 2027.
If Patterson is ordered a retrial, the drama and other content about the case could be in doubt as pre-trial rules would once again apply.
That means there could not be any coverage about the case until the retrial.
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