Commissions of investigations came into being in 2004 when an Act of the same name passed through the Dáil.

Then minister for justice Michael McDowell drove the idea, which was a response to the widespread recognition that tribunals of inquiry were unwieldy and had run up enormous costs.

By that stage the Moriarty and planning tribunals had been running for seven or eight years with no sign of an end. There was also the danger that by the time the reports on the tribunals were published the original controversies would be distant memories.

McDowell identified two factors that had contributed to the escalating costs and drawn-out tribunal time frames: the public hearings and the adversarial nature of the proceedings. Virtually every witness was lawyered up and nearly every appearance involved months of tortuous correspondence.

The commission sought to simplify inquiries into matters of significant public importance and concern. Nevertheless, each commission retained most of the powers of tribunals of inquiry, including the right to compel witnesses and discover documents.

Evidence given in private

In essence, what distinguishes a commission from a tribunal is that most of the evidence is given in private rather than public. The Act also excluded lawyers from the proceedings unless their presence was deemed necessary in the interests of natural justice. The evidence was to be gathered in an interrogatory rather than adversarial manner – ie without cross-examination.

Once the commission has concluded its work, it furnishes a report to the Minister who established it. The longest time span so far has been three years, an infinitesimally small period compared with tribunals.

In the past decade there have been a number of high- profile commission of investigations. The one that investigated how the Archdiocese of Dublin handled cases involving sexual abuse of children by priests was chaired by Judge Yvonne Murphy. It investigated 46 sample cases – some of the names of the offenders were not disclosed.

The commission’s report had far-reaching ramifications. One of its key findings – that the Archdiocese was more concerned with maintaining secrecy than ensuring justice was done – was very damaging. The report led to the resignation of four bishops with links to the archdiocese. The Vatican was also harshly criticised by, among others, Taoiseach Enda Kenny for the negative and non-co-operative stance it adopted to the commission.

Commission on banking

In more recent years, a commission of investigation chaired by the Finnish banker

Peter Nyberg

examined the events that contributed to the collapse of the banking sector in

Ireland

. The report was critical of the previous government, the “soft touch” regulatory set-up and Government departments.

Like other such investigations, the commission was completed in an expeditious fashion but did not go into rigorous detail about what had occurred on the night of the bank guarantee in 2008.

Because evidence heard in private, what has been included or excluded for consideration by a commission has not always been apparent. Nor has the direction taken always been.

There was some muted criticism of the Murphy report from clergy in Dublin who claimed that the commission had given insufficient regard to some of the arguments made in defence of diocesan authorities. However, Archbishop of Dublin Diarmuid Martin accepted the report and its conclusions in their entirety.

Currently there are two commissions of inquiry under way. One, chaired by Judge Nial Fennelly, is examining covert recording of telephone conversations over many years in Garda stations. Its interim report on another matter, the events leading up the resignation of former Garda commissioner Martin Callanan, is due to be circulated to interested parties soon.

The second commission, established this year by Minister for Children James Reilly and again chaired by Yvonne Murphy, was prompted by media reports on apparently high mortality rates in mother-and-baby homes and the burial practices in those homes.