A dead woman's fight to get ACC cover has continued to be debated in the Court of Appeal.
Deanna Trevarthen died in 2016 from mesothelioma, a lung cancer caused by asbestos fibres.
Before her death, she pushed to get ACC cover for financial assistance, but was rejected because she was not exposed to asbestos at work.
As a child, Trevarthen was exposed to asbestos by hugging her father, who was an electrician. He was often in work clothes and had been exposed to asbestos on the job.
There has been no disputing the fact asbestos fibres caused Deanna Trevarthen's lung cancer but, while alive, she was denied cover by ACC because it was not a workplace injury.
After her death, her family continued the legal battle and last year a High Court decision by Justice Mallon ruled the corporation was wrong - and should have accepted her claim.
ACC has appealed the decision, saying it raises significant questions about the boundaries for ACC cover.
The test is whether she suffered personal injury by accident.
At the Court of Appeal, ACC lawyer Paul Radich QC questioned whether the fibres caused irreparable damage from the outset.
"We know the fibre entered - we know that it was there - but did it cause damage to the body when it entered - and perhaps the answer is yes," he said.
He said there was not enough evidence.
"What we do not know at the moment is whether the inhalation of a fibre caused damage in and of itself - we don't know was it the fibre that caused damage? Or was there no damage at that point? Or was there a process of some sort?" he said.
However, Beatrix Woodhouse - a lawyer for Angela Calver, who is representing Trevarthen's estate - backed Justice Mallon's decision.
She repeated it was an injury caused by accident.
"By the very fact that you have mesothelioma, it shows that you did have an inhalation of injurious fibres, and that's exactly how Justice Mallon framed the accident - is personal injury caused by accident - you need those two components," she said.
The Court of Appeal reserved its decision.