Mason's barrister Sally Robb had argued during an appeal hearing in May that there was a miscarriage of justice as the judge in the original trial did not properly summarise the defence case.

Justice Philip Morrison said in the appeal judgment the jury was properly instructed as Mason's defence was brief and straightforward.

"In this short and clear-cut trial, the defence position was simply and clearly put, both in the closing addresses and in the immediately following summing up," Justice Morrison said.

The jury heard Mason was still angry after an argument with Ms Parkes, and set alight a car parked under her house in the early hours of February 2020 and watched as she tried to escape.

Mason made no attempt to join bystanders in an attempt to rescue Ms Parkes.

Ms Parkes, 50, was found unresponsive huddled on the floor by a firefighter inside the home at Chermside in Brisbane's north.

She had suffered burns to 80 per cent of her body, most were down to the bone.

Four days later the mother-of-four's life support was turned off after enduring multiple organ failure from injuries caused by the fire.

Mason pleaded guilty to arson in the form of setting his own car alight but pleaded not guilty to murder.

Mason's defence was based on asking the jury members a series of questions as to whether he foresaw the consequences of his actions, that Ms Parkes' death was reasonably foreseeable and did Mason intend to kill or cause grievous bodily harm.

Ms Robb had argued the trial judge did not adequately explain this "question trail" that the jurors were encouraged to use in reaching their verdict.

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