The first directions hearing for the penalty fees class action running against ANZ got underway in the Federal Court in Melbourne yesterday.
The judge, Ray Finkelstein, proposed that both parties picked their best witness to try the case,
AAP reported.
"One case, one calculation, one fee - then hang your case on the result of that on the basis if you lose your best case then you lose the lot," he said.
Maurice Blackburn, the plaintiff lawyers, were open to this approach but Alan Archibald for ANZ said he believed it could be more complicated than that.
"It is an enormous and difficult case," Archibald said.
He said the bank's systems, processes and costs had changed over time so cases would be very diverse.
"Even if you focus on one account the task seems to be very, very large," he said.
But Justice Finkelstein said he would like to see the class action "stand or fall" on the best case with the other claimants "bound along the way".
Finkelstein was the judge in the Opes Prime case in 2008 in which early belligerence by the bank gave way to an early settlement - and a choice seemingly at odds with conventional bank litigation tactics.