The Irish Catholic newspaper has reported that Cardinal Desmond Connell signalled 16 months ago he was prepared to go to prison rather than allow privileged diocesan files to be released.
It quotes sources close to the Cardinal as saying he feels a direct and personal responsibility to those who got assurances of strictest confidentiality from him.
It says several victims of clerical abuse received them, along with accused priests who have not been convicted.
According to The Irish Catholic, Cardinal Connell told unnamed friends in Rome he would risk prosecution rather than breach the confidentiality of church files.
It says he made the comments in late 2006 when the Irish Bishops were reporting to the Pope.
Last week in the High Court, the Cardinal accused the Government-appointed Murphy Commission of unlawfully keeping him in the dark about agreements it reached with his successor, Archbishop Martin, to waive privilege on about 5,000 diocesan documents.
The paper reports that when the Cardinal complained to the commission that he was not being informed, as a relevant third party, of discussions between it and Archbishop Martin that led to the papers being handed over, the commission replied it had told the Archdiocese that relevant third parties could be informed.
Archbishop Martin's spokeswoman said he had informed Cardinal Connell of his intentions and motivations with regard to the legally privileged documents.