When Can Procedural Mistakes Lead to Irish Public Sector Planning Decisions Being Quashed

Introduction

A recent Supreme Court decision has clarified when procedural errors in the planning process will justify the setting aside of a public sector planning decision by way of judicial review. In Pat O’Donnell and Company v Dublin City Council[1] delivered on 2 July 2026, the Supreme Court considered Dublin City Council’s appeal against a High Court decision that had quashed the adoption of the Dublin City Development Plan 2022–2028.

Key Takeaway: Minor procedural errors will not automatically invalidate a planning decision. The courts will consider the purpose of the statutory requirement, the nature of the breach, any resulting prejudice, and the wider public interest before granting certiorari, i.e. cancelling the original decision.

 

What happened in this case?

The Council adopted a material alteration to its draft Development Plan 2022–2028. The alteration involved changing the zoning of land adjacent to Pat O’Donnell & Company’s premises from Z6 (Employment/Enterprise) to Z10 (Inner Suburban and Inner City Sustainable Mixed-Uses).

Pat O’Donnell & Company is a major supplier of heavy construction machinery and operates on a 24-hour basis from adjoining lands. The company had previously argued that its operations were incompatible with adjacent residential development and that resident complaints would be inevitable.

A submission opposing the zoning change was made on the company’s behalf by its planning consultant, Doyle Kent Planning Partnership Limited. However, in the published Chief Executive’s Report, the submission was recorded as having been made by “Doyle Kent Ltd” rather than by Pat O’Donnell & Company. Following adoption of the Development Plan, Pat O’Donnell & Company sought a judicial review of the decision.

 

What did the High Court decide?

In 2024, Holland J found in favour of Pat O’Donnell & Company and quashed the decision to adopt the Development Plan. The High Court held that section 12(8)(b)(i) of the Planning and Development Act 2000 imposed a mandatory obligation on the Chief Executive to identify the persons and bodies who had made submissions and to do so by specifically naming those persons. The Court concluded that the failure to identify Pat O’Donnell & Company by name constituted a breach of the statutory requirement and that the breach could not be excused as being merely de minimis, i.e. of such small consequence, that the wrong does not warrant a remedy.

 

What questions did the Supreme Court consider?

The Supreme Court granted the Council leave to appeal and considered three principal questions:

 

What Is the Purpose of Section 12(8)(b)(i)?

The Court considered whether the statutory requirement was satisfied where the report listed the planning agent who lodged the submission rather than the client on whose behalf the submission was made.

 

Can the Breach Be Treated as De Minimis?

The Court examined whether the alleged breach was so minor that it should not affect the validity of the planning decision.

 

What Factors Should Courts Consider When Deciding Whether to Quash a Decision?

The Court considered the broader principles that apply when assessing whether procedural non-compliance should result in a grant of certiorari.

 

What did the Supreme Court decide?

The Supreme Court allowed the Council’s appeal and overturned the High Court’s decision. The Court held that the Council had not breached the statutory requirement by listing the planning agent rather than Pat O’Donnell & Company itself in the Chief Executive’s Report.

 

Why did the Supreme Court reach this conclusion?

Delivering the principal judgment, Mr. Justice Woulfe concluded that the ordinary and natural meaning of the wording used in the 2000 Act was broad enough to include:

• the respondent;
• the respondent’s planning agent; or
• the planning agent acting on behalf of the respondent.

Accordingly, the statutory requirement had been complied with and no breach had occurred.

 

What test applies when a statutory requirement is breached?

Although the Court found that no breach had occurred, it considered it appropriate to address the remaining issues because they were matters of general public importance. The Court observed that the questions regarding de minimis breaches and certiorari formed part of a broader question concerning: the Court’s discretion whether to grant certiorari where there has been a breach of a statutory requirement and the relevance of factors such as whether the breach involves a mandatory statutory obligation or is capable of being treated as de minimis. The Court confirmed that the appropriate approach is the two-part test identified by Finnegan J in Gillen v Commissioner of An Garda Síochána[2].

 

Step 1: Did the Legislature intend the breach to cause invalidity?

The first question is whether the Oireachtas intended that non-compliance with the statutory requirement would automatically invalidate the decision. Where legislation expressly specifies the consequences of non-compliance, that intention will generally be decisive. Where the legislation is silent, the court must determine whether invalidity can be inferred from the overall statutory scheme, taking into account the context and purpose of the legislation. In this case, the Supreme Court noted that the consequences of any breach were not expressly addressed in the 2000 Act. It also considered that invalidity could not be inferred from the broader statutory framework.

 

Step 2: Should the court exercise its discretion in deciding whether to review lower courts’ decisions?

If invalidity is not intended as an automatic consequence, the Court must then decide whether it should exercise its discretion to quash the decision. The Court identified several relevant considerations, including:

• whether there has been substantial compliance with the statutory requirement;
• whether the breach is trivial, technical or de minimis;
• whether prejudice has been caused to the applicant;
• whether prejudice has been caused to the public; and
• whether there are public interest considerations weighing against invalidity.

 

Why was the alleged error considered harmless?

The Supreme Court stated that even if there had been a breach of the statutory requirement, the failure to list Pat O’Donnell & Company by name would likely have been regarded as trivial, technical or de minimis. The Court also found that Pat O’Donnell & Company had not demonstrated any prejudice arising from the Council’s decision to identify its planning consultant rather than the company itself. As a result, even if a breach had occurred, it would likely have constituted a “harmless error” that would not justify quashing the Development Plan.

 

Why is this decision important for public bodies?

This judgment provides important guidance for public sector bodies and planning authorities. It confirms that procedural non-compliance will not automatically result in a decision being invalidated. Where legislation does not expressly provide that a breach renders a decision invalid, the courts will examine the broader statutory scheme and assess the practical significance of the breach. The decision also highlights that courts will focus on substance rather than form, particularly where there has been substantial compliance and no prejudice has resulted.

 

What should public bodies and applicants take from this decision?

Public bodies should continue to comply carefully with statutory procedural requirements. However, this decision provides reassurance that minor technical errors will not necessarily invalidate an otherwise lawful decision. Applicants challenging planning decisions should be aware that identifying a procedural defect alone may not be sufficient. They may also need to demonstrate why the breach is significant and what prejudice resulted from it.

 

Conclusion

The Supreme Court ultimately held that Dublin City Council’s reference to the planning agent, rather than Pat O’Donnell & Company itself, in the Chief Executive’s Report did not breach the Planning and Development Act 2000. More importantly, the judgment provides valuable clarification on when procedural non-compliance will justify the quashing of a planning decision. The Court confirmed that factors such as substantial compliance, the seriousness of the breach, prejudice, and the public interest will all be relevant when determining whether certiorari should be granted.

 

Please contact a member of the Holmes Real Estate or Public Sector Groups for further advice.