The former Catholic archbishop of Dublin is taking legal action against the inquiry into the handling of complaints of child abuse by clergy.
Cardinal Desmond Connell has started legal proceedings
Cardinal Desmond Connell has said his successor should not have given files to the inquiry.
Archbishop Diarmuid Martin has told the inquiry he would be willing to hand over all diocesan files on abuse claims including those with legal exemption.
His predecessor argues they are covered by client/solicitor confidentiality.
Cardinal Connell says he is the client, not the archdiocese of Dublin.
It is understood the 5,000 files in question relate to both legal advice after allegations were made against priests as well as the insurance implications.
Cardinal Connell initiated High Court proceedings on Thursday.