International passengers involved in the Australian class action over the coronavirus outbreak on board the Ruby Princess have won their right to be included in the lawsuit, a judge has ruled.

Susan Karpik commenced representative proceedings against Carnival plc, the time charterer of the vessel, and Princess Cruise Lines Ltd, the owner and operator of the Ruby Princess.

The ruling will allow passengers from the United States and the United Kingdom to be included in the class action.

In Federal Court on Friday, Justice Angus Stewart rejected a preliminary application to stop a “sub-group” of overseas passengers from being part of the action.

Of the 2,651 passengers onboard, the respondents allege that 696 contracted their cruise on US terms and conditions and 159 contracted on UK terms and conditions. The balance are said to have contracted on Australian terms and conditions.

The differing conditions include a class action waiver clause in the US terms.

Ms Karpik alleges the respondents were in breach of their duties of care and allowed the voyage to proceed. She also alleged that they failed to take adequate measures to protect passengers from the risk of COVID-19 and also said they allegedly engaged in misleading or deceptive conduct and breached their consumer guarantees under the Australian Consumer Law.

But Justice Stewart ruled it wasn’t necessary or appropriate at this early stage of the proceedings to determine the law applicable to the US and UK sub groups’ negligence claims.

He noted a stay on the US passengers would result in the fracturing of the litigation with essentially identical claims being brought in the Federal Court and any stayed claims being brought in the US.

“Such a result is wasteful of parties’ and judicial resources and runs the risk of producing conflicting outcomes in different courts, which would bring the administration of justice into disrepute.”

The Federal Court was “not a clearly inappropriate forum” for the determination of the claims of the overseas passengers, the judge said.

Those claims had a substantial connection with NSW as many of the breaches of duty of care that are alleged concern conduct or omissions in Sydney.

A number of passengers contracted COVID-19 onboard the Ruby Princess after she departed from Sydney in on March 8, 2020 and returned from visiting a number of ports in New Zealand on March 19, 2020. Several passengers died after disembarking.

The case will return to court on September 17.