Subsequent Applications of Coolglass v ACP

On 4 February 2026, the Supreme Court issued its landmark judgment in Coolglass Wind Farm Limited v An Coimisiún Pleanála [2026] IESC 5. This decision allowed the Supreme Court its first opportunity to consider the effect of Section 15 of the Climate Action and Low Carbon Development Act 2015 (the “2015 Act”), following its amendment in 2021. The judgment provided clarity to public bodies on the extent of their obligations, when exercising their statutory functions, to engage with national climate plans, policy and objectives[1].

Several recent decisions by the Irish courts have considered the impact of the Coolglass decision. In the three months since the Supreme Court judgment in Coolglass, there have been eleven High Court judgments and one Court of Appeal judgment which refer to the Coolglass decision, three of which that are noteworthy. These decisions have offered clarity as to the application and scope of Section 15 of the 2015 Act, as amended, and shall be considered below, alongside the Government’s response in the form of the Critical Infrastructure Bill 2026.

Doyle & Ors v An Coimisiún Pleanála & Ors

Following Coolglass, Doyle & Ors v An Coimisiún Pleanála & Ors (No.3), delivered on 13 March 2026, was the first decision to expressly consider the Supreme Court’s ruling. The decision concerned proceedings brought by numerous environmental activists and NGOs seeking to quash a grant of permission for the development of six two-storey data centres in Ennis, Co. Clare. The Applicants’ arguments centred on the alleged failure of the Commission to consider and/or apply its mandatory obligation under Section 15 of the 2015 Act to perform its functions in a manner consistent with the State’s climate policies and objectives.

At the outset of his decision, Humphreys J set out a helpful summary of the Supreme Court decision in Coolglass. He noted that the Supreme Court had confirmed that the Section 15 obligation does not ‘create a simplistic traffic light system’ where climate-friendly projects must be granted planning permission, and where climate-unfriendly projects must be rejected. Humphreys J further noted that the language in Section 15 implies that there is a range of possible outcomes open to a pubic body which may satisfy the obligation, and a degree of tolerance in the manner in which it is achieved, and that the question for a Court to determine in any judicial review is whether the performance of the functions of the public  body falls within the spectrum of possible outcomes.

Turning to the issues at hand, the majority of the arguments raised by the Applicants concerned alleged inconsistencies with the Climate Action Plan and other climate policies, in view of the greenhouse gases (“GHG”) the project would emit.

Judge Humphreys rejected this line of argument. He reiterated that, post Coolglass, it is not the law that planning permission for a development that generates substantial GHG emissions and relies primarily on fossil fuels is automatically precluded by Section 15.  He also criticised the Applicant’s submission on GHG, which only considered gross GHG emissions, and did not consider the offsetting and mitigation measures proposed by the developer and included as conditions of the planning permission, which Humphreys J found were relevant to the consideration of compliance with Section 15.

Ultimately, he found that the Applicants had not demonstrated that the decision fell outside the range of options open to the Commission.  The decision highlights that Section 15 does not mandate particular outcomes in relation to proposed developments coming before relevant bodies, nor must all decisions result in the most climate-positive option.

Friends of the Irish Environment v The Minister for the Environment, Climate and Communications & Ors

Shortly following the delivery of Doyle (No.3), the Court of Appeal delivered its first judgment to expressly consider the Coolglass decision. The proceedings concerned an appeal following the High Court’s rejection of the Appellant’s challenge to the adoption of the Climate Action Plan 2023. The Plan was challenged on the basis that it breached the requisite requirements in Section 4 (as opposed to Section 15) of the 2015 Act, when adopting a Climate Action Plan (“CAP”), in particular the requirement under s4(2)(a) to “ensure” the CAP is consistent with the carbon budget programme.  The Appellant maintained that a CAP could only be adopted where the Minster had ‘a very high degree of confidence that the carbon budget programme will be complied.’ The Respondents argued for a lesser standard, one that precluded the level of proof/certainty sought by the Appellant, being one which was merely reasonable and evidence based.

The Court of Appeal considered and endorsed the Coolglass judgment, in particular the finding that the consistency obligation allowed a range of possible outcomes. The Court of Appeal found that while the use of the word “ensure” makes the obligation to ensure consistency under s.4(2)(a) marginally more onerous than the requirement to act consistently under Section 15, per Coolglass it is still not an obligation that reaches the heights of “comply with”. The Court reiterated that the statutory obligation is to ensure consistency with the carbon budget programme and – applying the findings in Coolglass – found that “this can be achieved in a number of different ways and the methods chosen may require to be amended in light of practical experience”.

Applying this, the Court found that strict compliance between the CAP and the carbon budget programme is not required, not least because the carbon budget programme is a moving target, subject to constant revision and amendment. The Court concluded that the measures proposed in a Climate Action Plan must be based on realistic evidence and be capable of producing results at or close to projected levels if they are fully implemented.

In the circumstances of this case, the Court found that the measures contained in the CAP23 were quantified and explained and that the Appellant had not not discharged the onus of proof (which it bore as the moving party in a judicial review) to show that the Minister had acted in breach of the 2015 Act in adopting CAP23.

Whilst this decision did not directly concern Section 15, it highlights the wider impact and applicability of the Court’s reasoning in Coolglass. It highlights that, where the relevant legislation provides that a public body act consistently with a policy or objective, it leaves a range of options available to a decision-maker. Once a decision-maker remains within this range, the Court is less likely to impugn a decision for failing to comply with this consistency obligation.

Friends of the Irish Environment v An Coimisiún Pleanála & Ors

A final recent judgment to consider the decision in Coolglass was delivered on 1 April 2026. The decision concerned a grant of permission for a gas-fired power plant in Co. Kerry. Amongst the arguments raised by the Applicant were claims that the Commission had failed to comply with its Section 15 obligation, both generally and as regards alleged inadequate consideration of the Climate Action Plan, Sectoral Emissions Ceilings ("SECs"), and carbon budgets. Humphreys J again set out a useful summary of the Supreme Court’s findings in Coolglass, including that s.15 is an enforceable duty that goes beyond a “have regard to" obligation but is one that allows a “spectrum” of outcomes, and reiterating that planning decisions cannot be reduced to a "traffic light" climate friendly “go”, climate unfriendly “stop” system.

In relation to Section 15, the Applicant contended that the project should not be permitted due to its GHG emissions. However, as Humphreys J noted, the intention behind the plant was to supplement the energy developed by renewable sources, and when viewed in its context, the project was devised, in part, to avoid a need for ‘more carbon intensive power generation.’ As firmly stated by Humphreys J ‘the applicant has not shown that the margin of evaluation has been exceeded.  Net zero by 2050 does not mean zero use of gas right now…’.

The Court’s practical approach to what was ultimately a climate negative project is of critical importance. Whilst this project was a climate-negative proposal, viewed in context, it was clearly envisioned as an element of the State’s climate transition, supplementing and supporting the State’s renewable energy production. Furthermore, the express consideration of a lack of suitable or better alternatives was another factor which indicated Section 15 compliance, notwithstanding the climate-negative nature of the project itself.

Key Takeaways 

Some key takeaways from the above decisions are as follows:

• Section 15 of the 2015 Act does not mandate a single approach to be taken by public bodies. Rather, it allows for a range of options which, once capable of justification, are equally permissible (a so called “spectrum of outcomes”).
• The level of difficulty in establishing a decision’s consistency with Section 15 varies on a case-by-case basis.
• In considering GHG emissions for Section 15, a decision-maker is entitled to consider either the gross GHG emissions or the net emissions, following offsetting and mitigation.
• A project shall not be rejected as inconsistent with Section 15 merely as it creates GHG emissions, if it can be demonstrated to be otherwise compliant with climate objectives.

The legislative responsive: The Critical Infrastructure Bill 2026

The reaction to the Supreme Court decision in Coolglass has not been limited to the Irish Courts. The recently published Critical Infrastructure Bill 2026 appears to be a tailored response to the Supreme Court’s judgment and its implications for public bodies under Section 15 of the 2015 Act.

Section 3(1) of the Bill affords the Government the power to issue a “designation order" designating a project or programme as a critical infrastructure project or programme. Such a designation order can only be made on foot of a recommendation of the Minister for Public Expenditure, Infrastructure, Public Service Reform and Digitalisation pursuant to Section 3(2). Section 3(3) sets out the matters which the Minister may have regard to in making a recommendation, such as the need to ensure effective and efficient delivery of a project, whether delay, disruption, or failure to deliver the project / programme may have adverse economic or social consequences for the State; whether a project or programme may impact in a positive or negative manner on the delivery of any other project or programme; the National Development Plan 2021-2030 (and amending/replacing documents), and such other matters as the Minister considers appropriate.

Section 4 of the Bill provides that a public body becomes a “relevant public body” for the purposes of the Bill in so far as it performs functions in relation to a critical infrastructure project or critical infrastructure programme, with those functions defined as “relevant functions”.

In turn, Section 5 sets out a number of additional functions that a relevant public body must carry out where a designation order is made, and provides that a public body must prioritise the performance of its relevant functions over the performance of its other (ordinary) statutory functions. These include duties such as acting in an expeditious manner, co-ordinating with other relevant public bodies, and allocating resources, as appropriate, to facilitate the carrying out of these duties.

Section 6 enables the Minister to give a direction to a relevant public body (which must be complied with) on a range of matters, including measures to be adopted for the purposes of carrying out its duties under section 5 as regards relevant functions.

The critical provision of the Bill, and in direct response to Coolglass, is Section 7. This section provides that, in relation to a project or programme designated as critical infrastructure, s15 of the 2015 Act is inapplicable to a relevant public body where it is performing its relevant functions (i.e. its functions relating to a critical infrastructure project or programme), the carrying out of its duties under the Bill, or complying with a Ministerial direction under section 6. 

Overall, the Bill is clearly aimed at speeding up the delivery of critical infrastructure in the State. It attempts to do so by reducing the time, insofar as possible, between planning such a project and beginning to deliver it. Whether this Bill can successfully realise these aims, and how frequently its provisions shall be invoked, remains to be seen.

The evident purpose of disapplying Section 15 is to seek to reduce the scope for judicial review challenges (and the delays associated with it) to a critical infrastructure project or programme.  While disapplying section 15 will narrow the available avenues of challenge to the ultimate decision on whether to grant planning consent to critical infrastructure, it may at the same time open up a different avenue of attack where a party could seek to challenge the validity of the designation order itself.

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For more information, please contact authors Mona Costelloe (Partner, Litigation and Regulation), Robert McDermott (Managing Associate, Litigation and Regulation) and Mark Ramsay (Litigation Paralegal). The team at Byrne Wallace Shields LLP acted for An Coimisiún Pleanála in the Coolglass proceedings.