A trainee midwife sentenced to life imprisonment for murder, who claimed she was looking for her shoes in a car park when the fatal attack occurred outside a Bradford pub, has failed to overturn her conviction.

The court of appeal’s ruling in the test case of Laura Mitchell was greeted with dismay by supporters who have been campaigning for changes to the controversial “joint enterprise” rules.

Her appeal against her conviction was the first to be referred by the Criminal Cases Review Commission (CCRC) under new judicial guidance for joint enterprise cases. Her lawyers argued that the conviction was unsafe.

Mitchell, then 22, was outside the bar in January 2007 with her boyfriend Michael Hall, also 22, when a fight broke out over who had booked a taxi.

During the initial scuffle, Hall was seen to have pulled the victim, Andrew Ayres, 50, off Mitchell.

She was later seen wandering around the car park and subsequently said she was trying to find her shoes, which had been lost.

In 2016, the supreme court ruled that a key test imposed by judges in assessing guilt in joint enterprise cases – where the accused acts in conjunction with the killer but does not strike the blow that causes death – had been incorrectly applied for 30 years.

Courts had misinterpreted the foresight rule, the supreme court said. Foresight of what someone else might do was merely part of the evidence. “It is for the jury to decide on the whole evidence,” the judgment said, “whether [a secondary party] had the necessary intent.”

The court of appeal has heard a series of applications since then from those imprisoned under the discredited joint enterprise guidelines. Only two have so far resulted in sentences being reduced or convictions overturned. Mitchell had already been through the appeal process so her case had to be referred by the CCRC.

The grassroots organisation, Joint Enterprise Not Guilty By Association (Jengba), has led the campaign to overturn convictions, securing the support of the Commons’ justice select committee, the playwright Jimmy McGovern and senior lawyers such as Lord Hooper, a retired appeal court justice.

In a statement issued afterwards, Jengba said: “Laura is a young mum, a trainee midwife. She had gone on a night out, there was a row about a taxi, she didn’t instigate any fight. She was pulled from the taxi and thrown to the floor.

“The evidence of the case proves that Laura did not inflict the blow that tragically killed the victim, and that she was not at the scene when that fatal blow was delivered. She was not part of a plan to murder and she had no foresight that the actions of another would lead to the death of the victim.”

Gloria Morrison of Jengba added: “How tragic and unjust is it that a young mum has had to spend 12 years in prison for something she did not do.”

The Labour MP Lucy Powell said on Twitter: “The Laura Mitchell case was seen as the most clear cut case of substantial injustice of joint enterprise. That it’s not even got over the first hurdle shows that the ‘wrong turn’ judgment of the supreme court is now meaningless”.

Mitchell lost an earlier appeal against conviction in 2008. Her case has become the first to be referred by the CCRC, under its statutory powers, to the criminal court of appeal under changes made by the supreme court’s 2016 ruling.

Tim Moloney QC, for Mitchell, told the court: “There’s a sufficiently strong case that a jury properly directed would not have convicted the appellant. The substantial injustice she has suffered is compounded by the life sentence.”

Although Mitchell was involved in punching and kicking in the initial phase of the fight, the court heard, she did not go to a nearby house where others collected weapons including a CS gas spray and a metal flail.

However, Lady Justice Hallett of the court of appeal said it dismissed the application because Mitchell was party to the initial fight and had not communicated to her friends her intention to withdraw from the violence. A jury could therefore have inferred that she was still party to the later, fatal blows.

Under existing criminal court rules, there are exacting standards for defendants if they want to argue that they “withdraw” from a joint enterprise. They have to be able to demonstrate that they clearly communicated their intention to back out to those they believed were the principal attackers.

“There was no evidence that she was part of the plan to get weapons,” Moloney said. “She was encouraged to move away but she insisted on staying on to recover her shoes.

“She was heard saying: ‘I want my shoes.’ It was clear from a number of prosecution witnesses that she had lost her shoes and wanted to find them.”

Mitchell appeared by remote video link from prison. She spoke at the beginning of proceedings only to confirm her name.