The lawyer for the company convicted over the Whakaari/White Island eruption says it has "recast" the legislative direction on who is responsible for health and safety issues.

A lawyer for the owners of Whakaari/White Island says the conviction of their company has "concerning implications" for other landlords permitting adventure activities on their land.

The owners of the island are challenging the criminal conviction of their company at an appeal hearing that continues in the High Court at Auckland today.

Whakaari Management and four other companies were fined and ordered to pay more than $10 million in reparations for health and safety failings in the lead up to the 2019 volcanic eruption that killed 22 people.

Lawyer Rachael Reed KC told the court on Tuesday the landlord WML's conviction "recast" the legislative direction on who is to be responsible for health and safety and that was "unjustified".

Reed said other landlords were waiting for the outcome of the appeal hearing before deciding whether to give access to their land.

She said the tour companies operating on Whakaari were responsible for safety, with the landlord granting access on the proviso any activities would be conducted safely.

She likened the arrangement to that of a port company which would carry the duty of workplace safety, rather than the landowner.

"Just like any landowner, it [WML] had the ability to and did grant the right of access to the land through licences. That is what it did. It did not run the tours. It did not direct or supervise the tours."

Reed said the tour companies - who have pleaded guilty under the Health and Safety at Work Act (HASWA) - put tourists in harm's way and were there to manage their safety.

The focus is on section 37 of the Act, which requires the person controlling or managing a workplace to ensure anything arising from the workplace, including entries and exits, are without health and safety risks.

Reed told the court the landlords were not managing a workplace, instead the tour operators were.

"WML gave the right to access Whakaari and The Walking Tour site when approached by the tour operators and asked to do so. And they asked the tour operators to use that right of access responsibly. That is the extent of it."

Reed said the appeal sought to retract the implications for other landlords permitting adventure activities on their land.

She said after the eruption, WorkSafe did not change its advice to other landowners to say they could be liable for adventure activities conducted on their land.

A charitable trust that advocates for access to climbing and outdoor recreation areas is joining the appeal hearing as an intervenor; an entity or person who may be affected by the decision but who is not party to the legal proceedings.

Justice Simon Moore said the Aotearoa Climbing Access Trust had permission to make submissions on aspects of the judgement that directly affects climbers.

After the deadly eruption in 2019, WorkSafe conducted an extensive investigation into health and safety and took its findings to trial - WML was fined $1 million and ordered to pay $4.8 million in reparations to victims and their families.

Survivors and victims families are listening to the hearing remotely.

Opening the hearing, Justice Simon Moore acknowledged the 22 people who died and the 25 who survived but with serious injuries.

He said most appeals come down to a reasonably narrow or fine point, and this would likely focus on whether Whakaari Management had a duty under section 37 of HASWA and if it did, did it breach that duty as WorkSafe claims it did.

"That summary is incredibly simplistic, they are just headlines, the arguments that we will hear for and against those propositions will be very much more fine grained and detailed."

Reed said the arguments heard in the hearing "may appear sterile and cold, and that is not intended in any way to be disrespectful".

She said it would require an analysis of the law in a structured and methodical manner.

In Judge Evangelos Thomas's decision following the trial last year, he said the company 's failure to get risk assessments exposed others to risk of serious injury and death.

He said WML also consequently failed to install facilities that would mitigate the risk, and failed to ensure workers and tourists were supplied with appropriate personal protective equipment.

During the trial, the court heard the court had heard that WML was earning about $1 million a year from charging tour operators an annual licensing fee, based on a fee for each individual visiting the island.

The hearing is set down for three days.

-RNZ.