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The procedures that regulatory decision-makers must follow in making decisions is a well-trodden area of administrative law. What is less discussed is the decision-making process itself. What evidence are decision-makers entitled to rely on? And what steps are they obliged to take in assessing evidence before them?

The answer is “It depends…”

The starting point in deciding what evidence a statutory body is entitled to rely on should always begin with a detailed review of the legislation on which it was founded, particularly its functions.

This was recognised by the High Court in the case of Ashford Castle Ltd v SIPTU. Mr Justice Clarke, as he then was, stated that at one end of the spectrum lie issues involving mixed questions of law and fact. For example, deciding whether a person is entitled to social welfare benefit according to requirements laid down by statute. At the other end of the spectrum, a decision maker must bring their own expertise into evidence in relation to matters involving the exercise of an expert judgment, independent of questions of disputed fact. For example, planning decisions concerning the proper planning and development of a particular area, or the Labour Court in fixing pay rates.

Mr Justice Clarke also touched on the issue of regulators obtaining expert opinion which is later disputed. Clarke indicated that this may be resolved “in a manner similar to the way in which similar issues would be resolved in the courts, by hearing and, if necessary, testing competing expert evidence.” However, he added that “above and beyond the resolution of any such issue of expert fact, the authority concerned will also have to bring to bear its own expertise on what is the proper planning and development of an area.”

Testing expert evidence?

Interestingly, a recent, and lengthy High Court decision in Cork Harbour Alliance for a Safe Environment v An Bord Pleanála has added some nuance to the Ashford Castle case. Particularly regarding the testing of expert evidence by regulatory decision makers.

Cork Harbour Alliance for a Safe Environment (CHASE), an alliance of community groups based in Cork Harbour, objected to a decision made by An Bord Pleanála to issue a pollution control licence. One of CHASE's grounds of challenge was that An Bord Pleanála failed to deal with alleged false evidence and credibility issues during the decision-making process. It was decided that the Board had “a jurisdiction and a duty to resolve the issues of credibility and competence and of the reliability of the documentation and data provided by them”. CHASE relied on the Ashford Castle case in this regard.

In considering this ground for the challenge, Mr Justice Barniville carefully contemplated the role of An Bord Pleanála under the relevant applicable legislation. Following this analysis, the judge found that it did not support the claim that the Board was “obliged to resolve the issues of credibility, reliability and competence on the part of experts.” He concluded that what the Board was required to do was “to consider the submissions made … and set out clearly in its decision why it had reached the conclusions which it reached”. He noted that this was particularly the case where the Board’s decision would be read alongside two inspectors’ reports and the submissions made by various parties, which were on the public file. He noted that he did not rule out the fact that in exceptional cases the Board might find it necessary to resolve issues of credibility, reliability, and competence. However, he added that the Board did not find it necessary to do so in this case and was in a position to complete its functions as required by statute without doing so.


The recent decision in Cork Harbour Alliance for a Safe Environment again makes it clear that a careful analysis of the statutory basis for the decision maker’s role is essential to understanding the scope of the role. In fact, in that case, adhering closely to the requirements of the legislation made the decision maker’s role less difficult than had been contended by the environmental group.

For more information, contact a member of our Public, Regulatory and Investigations team.

The content of this article is provided for information purposes only and does not constitute legal or other advice.

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