In October 2023, the Federal Court found Carnival was negligent in its duty of care and misled passengers about safety on board before the ill-fated March 2020 voyage.
The ship departed Sydney for New Zealand only to return with 663 positive cases amongst the 2641 passengers, which included 1679 Australians. The voyage led to 28 deaths.
Just prior to a trial which began in October 2022, Carnival offered to settle the case for $15 million.
This was rejected by the passengers, who returned with a counter-offer of $69 million.
The larger sum was rejected by Carnival and the trial began, leading to Justice Angus Stewart's landmark October 2023 judgement.
In his findings against Carnival, the judge ordered the company to pay lead plaintiff Susan Karpik $4423 plus interest for her out-of-pocket medical expenses.
Ms Karpik had originally sought more than $360,000 for damages to injuries, distress and disappointment.
On Wednesday, Justice Stewart ordered Carnival to pay Ms Karpik and her legal team at Shine Lawyers their costs of running the case up until the $15 million settlement offer was made on October 5, 2022.
However, he refrained from deciding who should pay the costs past that date until the total amount of compensation owed to passengers eligible for the class action was determined.
Judges have the ability to order a successful plaintiff to pay the legal costs of a defeated party if the amount they receive through court is less than that offered in a rejected settlement.
Ms Karpik argued it was reasonable to reject Carnival's settlement offer because the deduction of between $5.85 million and $6.75 million in legal costs would have left passengers with only a "relatively modest amount".
However, Justice Stewart said it was currently impossible to determine how much Carnival would have to pay.
There was no way to assess how many passengers were eligible for compensation and what the size of their claims were, he said.
Ms Karpik's individual claim revolved around the illness of her husband Henry, who had to be placed in an induced four-week coma after contracting the virus, and his need for ongoing care.
Ruby Princess departed from Sydney for New Zealand on a 13-day round trip, but returned 11 days later when Australia's borders were shut in the early days of the pandemic.
The matter will next come before the court on April 12.
