Expert Evidence in Judicial Review

The Court Clarifies What is Required

Expert evidence is becoming more important (and the law around it more complex) for both developers and objectors in planning Judicial Reviews. That is the effect of a series of recent judgments in the High Court. This development clearly has relevance for litigation but it also has wider implications all the way back to the preparation of planning applications and objections thereto.

It would be reasonable to argue that the law as stated in these cases is not new. I consider it beyond doubt, however, that we are now seeing the law set out more clearly than ever before (see, for example, less clearly, Barr J in Donnelly v An Bord Pleanála [2021] IEHC 834 §§124/30) and more strictly applied. Both developers and objectors need to be aware of the increasing rigour in this area of law.

In what follows I look at;

• the law as stated in this recent series of cases

• some thoughts arising

• the practical conclusions to be drawn, with two particularly for developers and those advising them

The Recent Cases

In chronological order, the recent cases dealing with this area are as follows;

Eco Advocacy v An Bord Pleanála (No 1) [2025] IEHC 15 (15 January)

100 Meter Tall Group v ABP [2025] IEHC 42 (31 January)

FoIE v Minister for Environment [2025] IEHC 61 (7 February)

Massey v ABP (No 2) [2025] IEHC 206 (11 April)

The Law

100 Meter Tall concerned a retention permission for a single 800kW wind turbine approximately 2km north of Limerick City. The turbine was constructed a “modest” (§1) 36m out of its permitted position and retention permission was granted by the Planning Authority. On a Third Party appeal, An Bord Pleanála granted permission (314887). It is that decision which was challenged.

In his judgment, Humphreys J said of cases in which defective EIA or AA is alleged that;

"Apart from (i) failure to consider something that the decision-maker was autonomously required to consider, (ii) patent flaw on the face of the materials, or (iii) other legal error, inadequate consideration or failure to dispel scientific doubt has to be established by admissible evidence (normally expert evidence)...If admissible evidence is put forward demonstrating scientific doubt arising from the decision-maker's approach, and such evidence is contradicted, in the absence of cross-examination then such a conflict must be resolved against the applicant..." (§85(vi), emphasis added, see also §151)

(Resolution is against the applicant because it is the applicant who bears the burden of proof in Judicial Review, see Eco Advocacy (No 1) §63(vi))

"As to what an applicant needs to do, that isn't too difficult...Leaving aside something that a court can evaluate as being a flaw on the face of the material, an expert...would need to aver...that the material before the board would be seen by a reasonable expert as creating doubt that has not been dispelled, or that the board's scientific approach is flawed on its face as seen by a reasonable expert, or that reasons given by the board would not be seen by a reasonable expert as dispelling scientific doubt..." (§202 and see §240)

The comments of Humphreys J above were in a judgment upon an application to re-open a Judicial Review hearing (§§34/5) in the light of a judgment which Humphreys J had given in Eco Advocacy (No 1) in which "things boil[ed] down to whether the applicant ha[d] demonstrated a defect in AA on the evidence." (§98)

In Eco Advocacy (No 1) Humphreys referred to;

"...the misconception that it is the mere assertion of doubt that creates doubt and that thereby invalidates a conclusion [in AA] of no scientific doubt. But an applicant has to do more than assert – it has to demonstrate the doubt...[T]he normal way to do that (apart from some patent error on the face of the material) is to put up an expert in the [JR] to state that a reasonable expert in the position of the board would have seen the conclusion as flawed." (§§100 and 102)

"Complaints like "too much weight" or "there is a possibility' are factual assertions which need to be demonstrated by expert evidence." (§133)

In FoIE the primary question was whether the applicant had "evidentially" established that the Climate Action Plan 2023 was insufficiently detailed (§1), "an exercise that would normally require expert evidence" (§122).

Humphreys J stated that;

"the complaint that the figures aren't justified doesn't get off the ground when the applicant hasn't made any real attempt to engage with the material that the plan does contain...[T]hat complaint needs to be firmly situated in the context of detailed engagement with the totality of informaion that is there, not just whining that the plan could contain more. The applicant hasn't done that, and certainly hasn't brought forward expert evidence to show that..." (§129)

"...the applicant's approach of launching upon the court a detailed textual exegesis of the plan, without expert evidence, can't be the correct procedure" (§134). "What's lacking about the approach here is the lack of granular engagement with the detail of the plan by way of pleadings and expert evidence." (§137(xv))

Most recently, in Massey No 2, the Court was concerned with a challenge to the Board's permission (309121) for a SID wind farm on the Cork/Waterford border.

Humphreys J said that;

"...the court can be assumed to have an ordinary pedestrian level of understanding of scientific concepts, but nothing by way of special knowledge. The concept of a "flaw on the face of the material" means something that can be assessed without any special knowledge. Once the comfortable world of black and white starts slipping into shades of grey – once the apparently clear need for particular surveys pixelates...into granular questions...we are unexpectedly and unwillingly hurled from the comfortable oasis of error-on-the-face-of the material into the confounding wilderness of expert opinion." (§94)

A court can assess questions relating to alleged flaws on the face of the record unaided but not those relating to the relevance and validity of expert evidence.

Thoughts Arising

The position before the Board is different from that before the courts

Despite the fact that in Ballyboden v An Bord Pleanála [2022] IEHC 7 (§254) Holland J appeared to assume that third parties would have their own experts, “non-expert participants in planning processes are entitled to have their opinions considered by the Board. That is a difference between process before the Board and before a court.” (Holland J, Environmental Trust Ireland v An Bord Pleanála [2022] IEHC 540 §97, emphasis added).

“The general legal principle is that while members of the public may well retain experts, they are not expected to do so. Nor should they ordinarily be disadvantaged by not having done so. It suffices that they raise with the Board the issues which concern them and expect the Board to deploy its own expertise in the required critical analysis of the planning application.” (Holland J, Environmental Trust Ireland §236)

Experts are expensive

The cost of experts will add to the financial uncertainty that will likely be created upon the commencement of Part 9 (Judicial Review) of the Planning and Development Act 2024 ("PDA 2024") which provides that each party shall bear its own cots (s293).

Conclusions

The following practical conclusions can be drawn from the above;