Three of the country's most senior judges are to give rulings in the first criminal "joint enterprise" cases to come before the Court of Appeal since a landmark ruling raised the possibility that hundreds of convictions could be "unsafe".
Groundbreaking appeals have been brought by men convicted of group attack murders.
The legal challenges follow a Supreme Court decision in February that the application of the law on joint enterprise, otherwise known as common enterprise, had taken "a wrong turn" and been misinterpreted for 30 years.
The Lord Chief Justice, Lord Thomas, is heading a panel expected to provide guidance on how the law should now be applied.
The other panel members are Sir Brian Leveson, president of the Queen's Bench Division, and Lady Justice Hallett, vice-president of the criminal appeal courts.
At the heart of the case is the so-called "foresight principle" in joint enterprise cases. Used over the years to tackle gang violence, defendants have been convicted if they could have foreseen that a murder or violent act was likely to take place.
But the Supreme Court ruled that the foresight rule was being misinterpreted and juries had to decide "on the whole evidence" whether a person had the "necessary intent" to join in the commission of a crime.
The first of 10 test cases heard by the court concerns the safety of the conviction of Asher Johnson, his brother Lewis, and Reece Garwood, all in their 20s, who were jailed for life for murdering Thomas Cudjoe in an attack on a garage forecourt near a pub in Ley Street, Ilford, east London, in November 2012.
A fourth convicted man, Jerome Green, was seen in CCTV footage holding a knife and apparently stabbing Mr Cudjoe as he sat in the driver's seat of a Ford Focus.
Lawyers for the Johnson brothers and Garwood told the court there was no evidence of common enterprise between them and Green, and the CCTV did not show they had been involved in a planned attack.
There was also no evidence that they had given verbal encouragement to Green to carry out the killing.
The second case challenges the safety of the convictions of Tyler Burton and Nicholas Terrelonge. They were found guilty of murdering young father Ashley Latty in a group attack after a birthday party in Dagenham, east London, in May 2014.
Awaiting the outcome of those and other appeals before the panel are members of JENGbA (Joint Enterprise Not Guilty by Association), a grassroots group which helped to achieve the landmark Supreme Court ruling.
Group co-ordinator Gloria Morrison said: "It makes no sense to find people guilty of murder based purely on foresight alone - the idea that you know what someone is going to do.
"It is totally illogical and it has led to juries coming to conclusions based on assumptions."
JENGbA estimates some 700 individuals could be in line to have their cases reviewed in light of the guidelines laid down by Lord Thomas' panel.