A crime against humanity was when someone knew crimes were happening and had the power to stop them but chose not to, the state inquiry into how the churches handled child sex abuse heard on Monday.

Barbara Blaine, founder and president of the Survivors Network of those Abused by Priests (SNAP), told the inquiry: ''I recognise how extreme that sounds, but the evidence backs it up in three ways: priest-shifting [of abusers], refusal to co-operate with civil authorities and refusal to remove predators from ministry and keep them from children.''

Melbourne researcher, advocate and lawyer Judy Courtin is preparing a report about abuse in Australia, and especially suicides, to be given to the international court as additional evidence. More than 20,000 documents from other countries have already been presented.

SNAP Australia co-leader Nicky Davis quoted research by Ms Courtin that in 99.94 per cent of child sex abuse cases (Australia-wide, not just church ones) the offender is not convicted or flagged on any register, and is free to re-offend. Of the six convictions per 1000 cases, more than half are appealed - up to six times the rate of appeal on other crimes.

SNAP Australia co-leader Mark Fabbro said Peter O'Callaghan, QC, who investigates abuse cases for the Melbourne archdiocese, had dissuaded him from complaining to police over his violent sexual abuse as a boy by a Jesuit priest. He said Mr O'Callaghan had also advised him not to sue the Jesuits, ''because the priests had made a vow of poverty''.

''Not one arrest or prosecution was ever made of any Jesuit priest. Father X [his abuser] was still in active ministry late last year. He was shifted back and forwards across three states over decades,'' Mr Fabbro said.

Ms Blaine said canon (church) law, far from being a parallel code with Australian law, should have no more authority than the personnel policy of a big corporation, ''because that's what it is''.

Ms Davis told the inquiry at least two-thirds of US bishops kept priests on the job after admissions of wrongdoing, diagnoses of sexual disorders legal settlements or even criminal convictions. Two months ago Bishop Robert Finn of Kansas was convicted for covering up child abuse, but the jail sentence was suspended and the church has not removed him.

Similar research was not available for Australia, but Ms Davis said she had never spoken to or heard of a child victim in a religious institution whose abuse was not covered up in some form. ''Will it take a bishop or cardinal going to jail to force major change? Yes, that is exactly what it will take,'' she said.

She said church members and staff often said they wanted to tell police or courts what they knew about abuse but feared losing their jobs or friends.