Catholic leaders including priests, brothers and nuns should have to be licensed or regulated to practise, a royal commission has heard.
"I think that's the way we have to move, and I think it's inevitable that people who practise will be licensed or regulated in some way," he said at the Royal Commission into Institutional Responses to Child Sexual Abuse in Sydney on Wednesday last.
"Services benefit from a wide range and comprehensive sense of being held both accountable (and) supported... and at the end of the day, that's for the benefit of people who are most vulnerable."
The royal commission's final hearing into the Catholic Church has been exploring whether a program of supervision should be made mandatory for religious leaders.
Psychologist Dr Michelle Mulvihill said a program with well-trained staff would make priests and religious leaders more accountable and that she was willing to bet allegations of sexual abuse would have been handled differently if bishops and superiors had supervision.
Dr Leary said he didn't think a Catholic bishop would necessarily mention a child sex allegation to his supervisor because it may be deemed a confidential "moral issue".
He said a "reprehensible ignorance" led to the Church viewing child sex abuse as a moral rather than legal issue.
"We perpetuated a system where people would not think outside the silo," he said.