Lawyer and former trainee priest Kieran Tapsell said he did not accept commentary that the Pope was “somehow prevented by an intransigent Curia” from acting quickly and decisively to change church responses to child sex crimes, after the resignation of Irish abuse survivor Marie Collins.

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Mr Tapsell argued strongly at the royal commission that the church would not change until the Pope changed canon law and removed the secrecy provisions that protected church offenders, and the church from scrutiny about how it dealt with them.

“Pope Francis is an absolute monarch. He can change canon law imposing secrecy over all information obtained by the church on child sexual abuse cases with the stroke of a pen,” Mr Tapsell said.

“If bishops don’t do what he says, he can sack them. As Justice Peter McClellan told the royal commission, if there is to be any real change to the church in Australia, ultimately it has to come from Rome.”

Ms Collins resigned from the Papal Commission on the Protection of Minors on March 1 citing “shameful” resistance within the Vatican to changes recommended by the papal commission.

Her resignation came only days after papal commission member Baroness Sheila Hollins told the Royal Commission into Institutional Responses to Child Sexual Abuse that the church was a global organisation “struggling to come to terms with the safety of children and its responsibilities in that area”.

Ms Collins accused the church of “fine words in public and contrary actions behind closed doors”.

She accused Pope Francis of being misguided and ineffective on the issue of child sexual abuse after recent publicity about cases where the Pope had chosen “mercy” for convicted church child sex offenders and refused to defrock them.

“I feel (he) does not appreciate how his actions of clemency undermine everything else he does in this area,” Ms Collins said.

Pope Francis declined Brisbane Archbishop Mark Coleridge’s request to remove eight convicted priest child sex offenders from the priesthood, and dismissed just one – Francis Edward Derriman – whose crimes against children were revealed during a royal commission public hearing in 2013.

Another priest died and a decision against one other is pending, Archbishop Coleridge told the royal commission’s final hearing into the Catholic Church in February. Pope Francis assigned the remaining priests to “a life of prayer and penance”.

A smaller group of priests were permanently removed from ministry although they had not been convicted of offences. They were supervised by the diocese, the archbishop said.

Mr Tapsell said the “current problem with the cover up in canon law can be overcome with half a tweet”.

The Pope only had to add the words “all church personnel are obliged to report suspected abuse to the civil authorities” to a canon law amendment in 2010 by Pope Benedict, Mr Tapsell said.

The 2010 amendment was hailed as a significant step by the church. Pope Benedict directed bishops to report all child sex crimes to civil authorities, including historic allegations, in countries and states where it is a crime not to report serious offences to authorities.

The amendment only applies in a few countries and states because most do not make it an offence not to report a serious crime. In Australia only NSW and Victoria have laws where people can be charged for not reporting a serious crime.

Mr Tapsell said it was a serious concern that the papal commission did not have a canon lawyer, and lacked any focus on canon law’s role in maintaining secrecy about child sexual abuse within the church.

“Since 1996, the Catholic Bishops Conferences of Ireland, Great Britain, the United States, and Australia have wanted mandatory reporting under canon law (including cases of historic child sexual abuse), but have been continually rebuffed by the Vatican,” Mr Tapsell said.

“In 2002, the United States bishops put a proposal to the Vatican that included mandatory reporting but, like the Irish in 1997, they were told it did not comply with canon law.”

In 2014, the United Nations Committees on the Rights of the Child and against Torture asked Pope Francis why the Vatican did not impose mandatory reporting under canon law, and the Pope replied that mandatory reporting would “interfere with the independence of sovereign states”, Mr Tapsell said.

“Unless a country prohibits reporting child sexual abuse to the police, canon law interferes with such sovereignty as much as the rules of golf,” Mr Tapsell said.

He supported calls for Australia to reconsider diplomatic recognition with the Vatican after the church refused a royal commission request for all information held by the Vatican about Australian child sex cases, and the church’s responses to those cases.

On 22 February Brother Ambrose Payne from the De La Salle Brothers told the royal commission that Pope Francis’s rhetoric about “zero tolerance” of child sexual abuse did not match the reality imposed by canon law.

Canon law requires a religious brother to receive a “canonical warning” before he can be dismissed. Brother Payne said it was “a bit late” to require warnings after the abuse had occurred.

“The abuser has to offend again after a canonical warning has been given before he can be dismissed,” Mr Tapsell said.

“Similar problems arise with the disciplinary canons dealing with priests. Not a word has changed in Canon 1341 that requires a bishop to try and cure the priest before he is put on a canonical trial. Not a word has changed in Canon 1321, which two Vatican appeal courts interpreted as meaning that a priest cannot be dismissed for paedophilia because he is a paedophile.  Not a word has come from the Vatican indicating that these canons are being interpreted differently from the past.”

Pope Francis advised the United Nations that only one quarter of all priests found to have sexually abused children had been dismissed.

“That’s a 75 per cent tolerance of offenders, not zero,” Mr Tapsell said.

“The lack of consistency between his rhetoric and his actions on child sexual abuse could turn out to be the major blot on his papacy.”

Mr Tapsell is the author of Potiphar’s Wife: The Vatican’s Secret and Child Sexual Abuse.