"The difficulty is the myriad of issues," he said, questioning whether his client had been charged with the correct count and what the circumstances were that led to the jury finding Kevin King guilty.
Counsel said they were dealing with two separate actions which raised questions over manslaughter by an unlawful act. One was the choker hold Kevin King had put on Mr Heagney to subdue him and whether that had rendered the young man unconscious so that he could not protect himself.
The other was whether, when King and another staff member were throwing Mr Heagney out of the bar, they accidentally dropped him or whether he was deliberately thrown onto the ground.
"There is a blurring of the lines," said Greg King.
"It becomes so problematic when the jury is faced with multiple scenarios."
Said Justice Raynor Asher: "The manslaughter charge turns on the act of death and what caused that death."
It was always going to be a matter of fact and degree, but "we are dealing with an assault that caused death. That is the reality."
Citing the "uncertain state" of the evidence, Mr King asked: "Did the assault by neckhold cause his death, or did dropping him (Mr Heagney) on the footpath?"
Crown lawyer Cameron Mander said there were "many and varied" grounds of appeal but the main one was related to the way in which the trial judge directed the jury over the unlawful act that constituted the charge.
"Mr Heagney's death was caused as a result of the way (Kevin) King removed him from the bar. That was the scenario," said Mr Mander.
"It was one incident at one location at one time, and it happened in a matter of seconds."
King had been "physically involved" from the moment he approached the young man from behind - who was in an altercation with a bouncer - until he released him outside "deliberately or not."
The Crown case was that it was an ongoing and continuing assault, with King manhandling a patron, rending him insensible by a choke hold, physically removing him from the premises and intentionally dropping him to the ground.
The manslaughter charge encompassed those aspects.
"In this case the criminality involves use of excess force in the removal of a patron from a bar," said Mr Mander.
The Appeal Court judges have reserved their decision.
Outside the court, Matthew Heagney's emotional parents and his partner, who sat through the lengthy hearing, said they had come "to see how the system actually works" and to support Matthew's memory.
