Section 160 PDA 2000 and the Rule Against Collateral Challenge

But Subject to EU Law?

Section 160 PDA 2000 and the Rule Against Collateral Challenge

But Subject to EU Law?

This is the first of two posts which will draw from the recent decision of the High Court in Malone and McAvoy v Laois CC and An Bord Pleanála [2025] IEHC 345 (23 June).

Malone was an application for relief under s160 of the Planning and Development Act 2000 (“PDA 2000”). Its judgment contains a helpful discussion of the nature of the s160 jurisdiction which discussion will remain applicable when the equivalent s351 of the Planning and Development Act 2024 (“PDA 2024”) is commenced, expected towards the end of this year or early next. Paragraph references below (§) are to Malone unless otherwise stated.

The Facts

Two lay litigants sought injunctions pursuant to s160 PDA 2000 restraining what they alleged to be unauthorised quarry development on lands at Ballymullen, Abbeyleix in the south of Co Laois between Portlaoise and Kilkenny towns (§1). Declaratory relief and reference to the CJEU was also sought in respect of various alleged breaches of EU law (mostly relating to EIA) by the planning authority and what is now An Coimisiún Pleanála (§2 and see §§6 and 12). The development in question was permitted by planning permissions which the Applicants said were defective because of these breaches. The Applicants alleged that the development was thereby unauthorised and within the purview of s160 (§2). The time limit for Judicial Review had long since expired and was not sought (§3). The Respondents sought orders striking out the proceedings as bound to fail (§4 and §8 - 10).

Section 160 – The Text

In so far as is relevant for this post, s160 provides that;

“(1) Where an unauthorised development has been, is being or is likely to be carried out or continued, the High Court...may, on the application of a planning authority or any other person...by order require any person to do or not to do, or to cease to do, as the case may be, anything that the Court considers necessary and specifies in the order to ensure, as appropriate, the following:

(a) that the unauthorised development is not carried out or continued

(b) …that any land is restored

The equivalent terms of s351 PDA 2024 are substantially the same.

The Nature of Section 160

In the course of his judgment, Holland J made the following comments regarding the nature of the s160 jurisdiction;

• “a bespoke, statutory and practical remedy for a particular mischief – unauthorised development.” (§85)

• “While by s160(1) a remedy may be imposed on “any person”, it is in my view clear that the remedy may only be directed to a person in a practical position to remedy...the unauthorised development...” (§85a)

• “There may be an argument in a particular case for joining the planning authority...” (§85b)

• “...the norm is a relatively quick and simple procedure focussed closely on remedying a particular unauthorised development...” (§85c)

• “Such injunctions may only be directed to persons who are owners or occupiers of the lands in question or are otherwise able, as a matter of private law right, to bring about the cesser and/or remediation of such unauthorised development.” (§178)

• “s160 PDA 2000 is not a proper means of seeking to compel a planning authority to exercise its statutory powers of enforcement – that would be classically a matter for mandamus in judicial review.” (§181)

• An applicant in s160 proceedings cannot recover damages (Ellis v Nolan, Unreported, High Court McWilliam J, 6 May 1983 and Waterford CC v Centz Retail Holdings [2020] IEHC 540) (§186)

The Rule Against Collateral Attack

Proceedings will not be permitted if they are, in effect, a challenge to a decision under PDA 2000 in respect of which the time limit for Judicial Review of that decision has expired (see my post of 19 December 2024).

“...[A] person who has obtained a planning permission should at a very short interval after the date of such decision in the absence of a judicial review be entirely legally protected against subsequent challenge to the decision that was made and therefore presumably left in a position to act with safety upon the basis of that decision.” (KSK Enterprises Ltd v An Bord Pleanála [1994] 2 ILRM 1 (SC)).

“At least at the level of broad generality there is a significant public interest advantage in early certainty as to the validity or otherwise of such public law measures. People are entitled to order their affairs on the basis that a measure, apparently valid on its face, can be relied on. That entitlement applies just as much to public authorities.” (Clarke J, Shell E&P Ireland v McGrath [2013] IESC 1)

There is “almost unending authority to the effect that unchallenged decisions stand – the fallacious contrary misconception was best described in UT [UT (Sri Lanka) v Sec State for the Home Dept [2019] EWCA Civ 1095 §38] as “the erroneous belief that every decision, no matter its provenance, nature or form, is always capable of being appealed or at least reviewed” (Humphreys J, Ballyboden Tidy Towns Group v An Bord Pleanála IV (No 2) [2025] IEHC 277, 16 May, quoted in Malone §117) (and see Malone, §95).

The question as to whether something is an impermissible collateral attack is a question of substance not form (Costello J in Narconon Trust [2021] IECA 307). If the effect of proceedings is to question a decision pursuant to PDA 2000 then such decision can only be challenged by Judicial Review.

In short, unchallenged, albeit unlawful decisions, are valid decisions. (See §129/30)

Section 160 and the Rule Against Collateral Attack

In Malone, s160 PDA 2000 was used, in effect, to facilitate an impermissible collateral attack against the (unchallenged) permissions for the development in question (§121). As Humphreys J had put it, little more than a month previously and typically more colourfully; “one cannot wander along and seek exotic declarations that have the logical implication that unchallenged public law decisions are invalid.” (Ballyboden v ABP [2025] IEHC 277, 16 May, §69)

Previous cases which have also found s160 proceedings to be impermissible collateral attacks upon decisions made under PDA 2000 include;