A butcher whose E. coli-infected meat killed a five-year-old boy should have been charged with manslaughter, a court has heard.
William John Tudor was jailed for a year for breaking food safety laws.
But Cardiff Civil Justice Centre heard the Crown Prosecution Service has admitted it made the “wrong decision” in not pressing manslaughter charges.
The infected meat which killed Mason came from Tudor’s butchers in Bridgend which also supplied more than 40 other schools in the south Wales valleys.
About 160 people fell ill during the E. coli outbreak.
The original inquest in 2010 into Mason’s death recorded a narrative conclusion. Delivering his verdict, coroner David Bowen said: “I have agonised over a verdict of unlawful killing but despite substantial, some might say horrific, breaches of food hygiene regulations the evidence is not strong enough.
“There is little doubt Mason was owed a duty of care and a catalogue of failures to observe basic food hygiene breached that duty.
“But it is not enough for there to be a breach of the duty of care, however extensive and reprehensible that may be.”
On Tuesday, Cardiff Civil Justice centre considered an appeal by Mason’s family to get the original inquest narrative conclusion quashed and a second inquest heard.
Mason’s family, including his older brother who was also infected during the outbreak, were all present in court.
Representing the family, Mark Powell QC, claimed the coroner got the original verdict wrong.
“We say the coroner misdirected the jury and misdirected himself as to the essential elements of the offence,” he said.
“We don’t say the coroner was acting improperly, we say he was wrong.”
Following Mason’s death, the CPS declined to press charges of manslaughter against Tudor, of Cowbridge, Vale of Glamorgan.
The hearing was told that the CPS have since said to the family that was the wrong decision.
Mr Powell said the family is motivated by “a desire to right a wrong”.
The hearing was told Tudor had sufficient training in food hygiene and knew there was a risk someone might die.
The Civil Justice Centre heard a judgement would be handed down at a later date.