An American priest has told the Royal Commission into Institutional Responses to Child Sexual Abuse that the Catholic Church has used canon law as an excuse for not taking action against clergy accused of molesting children.

The commission is investigating the conflict between canon and civil law, and secrecy within the Catholic Church hierarchy.

Father Thomas Doyle, a canon lawyer who first reported allegations of abuse to the Vatican in the 1980s, told the commission that the Catholic Church's canon law had been used as an excuse in some instances by ecclesiastical authorities for not proceeding and taking action against reports of sexual abuse.

"I've seen the canon that's called the pastoral approach consistently misapplied and used as an excuse to justify lack of action," Dr Doyle said.

"The focus seems to have been consistently on the priest.

"Either getting [him] off the hook, taking care of him or punishing him in some way."

Earlier this week the commission heard evidence that nearly 2,000 Catholic Church figures, including priests, religious brothers and sisters, and employees, were identified as alleged perpetrators.

Every Catholic archbishop in the country except for Hobart is being called to give evidence at the commission over the next three weeks.

Approach designed to avoid responsibility, priest says

Dr Doyle said there was no Catholic Church equivalent of the United Nations Convention on the Rights of the Child, or requirement that the victim's interests be put first.

"The best interest of the victims should be the overriding concern of applying the law," he said.

"The best interest of the victim is not necessarily finding any way to exonerate the priest."

Dr Doyle (second from left) said the church had been too focused on protecting perpetrators, not victims. ( Supplied: Royal Commission into Institutional Responses to Child Sexual Abuse )

Dr Doyle told the commission that the approach for dealing with paedophile priests was "nuts" and designed to avoid accountability and responsibility.

He said the method of merely trying to talk an accused paedophile priest "out of doing it again" was not appropriate.

"He's already committed a crime if the evidence shows that … you're not talking about stealing from the collection," Dr Doyle said.

De-frocking paedophile priests 'not the right solution'

Dr Doyle told the commission that de-frocking a priest was the ultimate punishment aside from excommunication, which he said had not been applied.

But he warned that laicising or defrocking paedophile priests was a dangerous solution on its own.

"If we laicise some of these men who are predators, sexual predators, we will have no authority over them and no way to control what they're doing," he said.

"And so for the sake of the safety of the community some have urged, and I'm one of them, that they not be laicised."

Dr Doyle said a better approach would be to put priests who had been convicted and released from jail into a setting where there was strict monitoring and psychological help.

"So that these men will not be roaming around … and could then go and molest other children," he said.

The commission asked why the same treatment could not be provided to laicised priests.

"That is not being done," Dr Doyle said.

"If he takes vows to a religious order he's in a sense part of a family. And there's still an obligation to care for that man as long as he's part of that family."

The commission heard the church had struggled to deal with men convicted of sex crimes who vanished after they were released, only to reoffend.

Catholic Church 'needs to change its culture'

Dr Doyle said he knew of one instance where convicted paedophiles were brought back into the religious order and "given a credit card and access to an automobile".

"There was no supervision and there were no questions asked," he said

"And one priest in this particular religious community challenged this to the superior and he was removed from the community."

Dr Doyle said it would be very difficult to change the culture unless senior church officials viewed the issue seriously.

He said it would be helpful "to have some form of legislation with teeth in it".

"For example if you do not conform to this you will be removed and you will not be able to fall back on a beaucratic maze," Dr Doyle said.

"But unfortunately the situation in the Catholic Church with its legal system is that … it's not consistent. It's not consistently applied. It's not consistently understood."