Josh Frydenberg?s pick for ACCC chief represented bank in one of regulator?s biggest criminal cases

Josh Frydenberg's nomination for chair of the competition watchdog may have to recuse herself from any decisions relating to one of the regulator's biggest cases if she is approved for the job.

Gina Cass-Gottlieb, a partner at corporate law firm Gilbert & Tobin, has represented a key participant in a criminal case alleging cartel behaviour that the Australian Competition and Consumer Commission brought against ANZ, Deutsche Bank CitiGroup and banking executives over trading in ANZ shares.

If approved by the states and territories, she will replace Rod Sims, who has served as chair for more than a decade, and become the first woman in the ACCC's history to take the role.

The banking cartel case is one of the ACCC's most difficult, with a federal court judge last month describing the indictment brought by prosecutors as a "complete shemozzle" because charges had not been finalised more than three years after they were first laid.

Prosecutors also dropped the charges against ANZ and its senior executive, Rick Moscati, last month.

Cass-Gottlieb was closely involved in the case, acting on behalf of investment bank JP Morgan, which earned itself immunity from prosecution after agreeing to provide evidence against other alleged players.

She personally met with prosecutors in October and November last year to outline the evidence JP Morgan employees were willing to give in the case.

Sims said the ACCC had robust rules to manage potential conflicts of interest under which Cass-Gottlieb would not be involved with the prosecution.

However, he said that although the ACCC originally investigated the matter, it was now in the hands of the commonwealth director of public prosecutions.

"So yes, we're providing backup support, but it's not as if we need to make more decisions," he said.

Cass-Gottlieb, who has been a partner at Gilbert & Tobin for 25 years, has regularly represented corporate clients who have tangled with the ACCC over competition law.

Sims said her experience made Cass-Gottlieb a good choice.

"You wouldn't want an ACCC that didn't have people who worked on both sides of the fence," he said.

"You don't come to the ACCC unless you've got some alignment with what the ACCC is trying to do, and I'm sure Gina does."

He said Cass-Gottlieb was "such a good candidate" to lead the ACCC.

"I'm delighted that we've had such a smooth transition which will continue it as a great institution," he said.

Sims' term, his third, finishes in March, by which time he will have served 11 years as competition tsar. He is already the ACCC's longest-serving chair.

"I think it never really became an issue to serve a fourth term," he said.

"I did have a chat to the treasurer about that [and] we both agree that was the sensible way forward."

In a statement, Cass-Gottlieb said she was "honoured to be entrusted to be the next chair of the ACCC".

"I look forward to stepping into leadership of this important regulator and its dedicated team of staff and commissioners and wish to acknowledge the lasting contributions Rod Sims has made to the ACCC and to competition law," she said.

Frydenberg also thanked Sims for his "outstanding contribution to competition, consumer and infrastructure policy in his time at the ACCC, helping to advance world-leading reforms including most recently with respect to the digital platforms".

"I also acknowledge his wider contribution to public policy during his distinguished public service career which spans more than three decades," Frydenberg said.

"I wish him well for the future."

Labor's treasury spokesman, Jim Chalmers, also thanked Sims "for his dedication, commitment, and contribution to the ACCC for more than a decade".

Her appointment is subject to the consent of the states and territories, which has not been withheld in living memory.