“Wholly Successful” for Costs Despite Undetermined Grounds:
Commentary on Palatine DAC v An Coimisiún Pleanála & Ors (No. 2) [2025] IEHC 607

1. Introduction

This ruling of Ms Justice Emily Farrell in Palatine DAC v An Coimisiún Pleanála & Ors (No. 2) [2025] IEHC 607 is a costs judgment arising from a successful planning judicial review. The core importance of the decision lies not in the planning merits, but in the clarification of how courts should treat an applicant’s success for costs purposes where:

• The applicant obtains the primary relief sought (an order of certiorari);
• Multiple substantive grounds were pleaded and argued; but
• The court found it necessary to decide only one ground and did not determine the others.

The judgment addresses, and clarifies, the interaction between:

• Section 169 of the Legal Services Regulation Act 2015 (“LSRA 2015”), which sets out the general rule that costs follow the event; and
• Order 103, Rule 39 of the Rules of the Superior Courts (“RSC”), introduced by S.I. No. 246 of 2025 (Rules of the Superior Courts (Planning & Environment) 2025), governing costs in planning and environmental proceedings where costs protection is in play.

The central question was whether the applicant should be treated as:

• “wholly/entirely successful”, so that the default position is a full award of costs; or
• “partly successful”, so that an apportionment or reduction in costs might be appropriate.

In resolving this, Farrell J discusses and applies recent higher authority, in particular the Supreme Court decision in ESB v Good [2025] IESC 40, and deploys the “big issues” approach to issue-based costs. The judgment provides practical guidance to litigants and lawyers in planning/environmental judicial review on how the courts are likely to treat costs where only one determinative ground is decided, and none is decided against the applicant.

2. Summary of the Judgment

2.1 Background and procedural context

The substantive judicial review (dealt with in a separate earlier judgment on 19 September 2025) concerned a planning permission granted by An Bord Pleanála (now replaced by An Coimisiún Pleanála). The applicant, Palatine DAC, challenged the Board’s decision on several grounds under ss. 50, 50A and 50B of the Planning and Development Act 2000.

Key contextual points:

• The applicant advanced seven core grounds at leave; leave was granted on all.
• At the substantive hearing it proceeded with five core grounds; core grounds 6 and 7 were modularised.
• The State respondents (Ireland and the Attorney General) were necessary parties only because of core grounds 6 and 7, and no order for costs was sought against them.
• The core relief sought was certiorari of the Board’s decision.

2.2 Outcome of the substantive judgment

On 19 September 2025, Farrell J granted an order of certiorari. The court held that:

• The Board had failed to provide reasons as to why it rejected the recommendation of its own inspector, who had concluded that the developer’s methodology on daylight/sunlight was insufficient to enable the impact assessment.
• The Board nonetheless granted permission, declining to follow that recommendation.
• The judge decided the case on this one ground only (identified as core ground 4) and held that it was not necessary to determine the other grounds.
• No ground was determined against the applicant; the other issues remained undecided.

2.3 Competing positions on costs

In the present (No. 2) judgment, the sole issue was costs as between the applicant and An Coimisiún Pleanála (“the Commission”).

Applicant’s position:

• It obtained the main relief sought (certiorari).
• No ground was rejected or decided against it.
• Therefore, it should be regarded as wholly/entirely successful, so that the usual rule that costs follow the event applies without reduction.
• It relied on s. 169(1) LSRA 2015.

Commission’s position:

• The applicant advanced multiple grounds but succeeded only on one.
• The applicant should be treated as “partly successful” under Order 103, Rule 39(1)(c) RSC.
• Costs should be limited to those which would have been incurred had the applicant confined the proceedings to core ground 4.

2.4 Decision on costs

Farrell J held:

1. The applicant was “wholly successful” in its application for certiorari within the meaning of s. 169(1) LSRA 2015, notwithstanding that only one ground was determined and the others were left undecided (paras. 17–18).
2. No ground or issue was decided in favour of the Commission. This differentiates the case from situations like ESB v Good, Watchhouse Cross, and Ventaway, where some issues were expressly decided against the successful party.
3. Accordingly, the court refused to apportion or reduce costs to reflect the presence of other, undetermined grounds (para. 22).
4. The court ordered that the applicant is entitled to its costs against the Commission, including:
   • reserved costs; and
   • the costs of written submissions;
   with such costs to be adjudicated in default of agreement (para. 22).
5. No costs order was made against the State respondents, consistent with the parties’ position (para. 1).

The judge expressly chose not to decide whether Order 103, Rule 39 applies retrospectively to proceedings commenced before the coming into force of S.I. 246/2025 (para. 14), because the result on costs could be reached by applying s. 169 LSRA and a general understanding of “wholly successful” without resolving the retroactivity question.

3. Detailed Analysis

3.1 The legal framework for costs

3.1.1 Section 169 LSRA 2015 – the default rule

Section 169(1) LSRA 2015 (quoted at para. 16) provides:

“A party who is entirely successful in civil proceedings is entitled to an award of costs against a party who is not successful in those proceedings, unless the court orders otherwise, having regard to the particular nature and circumstances of the case, and the conduct of the proceedings by the parties, including—
(a) conduct before and during the proceedings,
(b) whether it was reasonable for a party to raise, pursue or contest one or more issues in the proceedings, …”

Key features:

• Default entitlement: “entirely successful” party is entitled to costs against the party “who is not successful”, subject to a discretion to “order otherwise”.
• Discretionary factors focus on:
  • the nature and circumstances of the case; and
  • the conduct of the parties, including whether it was reasonable to raise or contest particular issues.

Farrell J’s central interpretative move is to explain what “entirely successful in civil proceedings” means in a multi-ground judicial review where only one ground is determined.

3.1.2 Order 103, Rule 39 RSC – special planning/environment costs rules

Order 103 Rule 39 (introduced by S.I. 246/2025) provides different default costs positions for an applicant with the benefit of a costs protection order (as often occurs in planning/environmental judicial review), depending on whether the applicant is:

• “unsuccessful at the substantive stage” – sub-rule (1)(a);
• “wholly successful at the substantive stage” – sub-rule (1)(b); or
• “partly successful at the substantive stage” – sub-rule (1)(c).

The Commission’s argument was that the present case falls within sub-rule (1)(c): the applicant was only “partly successful” because it only succeeded on one of several grounds.

However, as Farrell J emphasises (para. 13), Order 103 Rule 39 is expressly stated to be “subject to sections 168 and 169 of the LSRA 2015”. This makes the LSRA 2015 the statutory anchor for any interpretation of what “wholly successful” or “partly successful” means in this context.

3.1.3 Retroactivity and transitional provision

The proceedings were commenced before Order 103 came into force on 18 June 2025, and judgment was reserved before that date (para. 15). Regulation 2 of S.I. 246/2025 provides:

“These Rules shall apply in proceedings commenced both before and from the date on which these Rules come into operation.”

Theoretically, this raises the question whether Order 103 can apply to costs in a case where:

• proceedings pre-dated the commencement of the Rules; and
• the parties had already conducted their case and had not adjusted strategy in light of the new rules.

Farrell J recognises that if she needed to decide this retroactivity question, the fact that the parties could not have altered their conduct to take account of Order 103 would be a relevant factor (para. 15). But crucially, she decides that it is unnecessary to rule on the retrospective application of Order 103 (para. 14) because:

• The issues can be disposed of by applying s. 169 LSRA 2015 and general costs principles; and
• Effectively, the case fits the “wholly successful” category as understood under s. 169.

This is a pragmatic use of judicial restraint: the court avoids a potentially complex transitional law question that is unnecessary to the outcome.

3.2 Precedents and authorities cited

3.2.1 ESB v Good [2025] IESC 40

The Supreme Court’s decision in ESB v Good is central. While the full judgment is not set out here, Farrell J quotes O’Donnell C.J. (paras. 10–12) on how courts should approach issue-based costs.

O’Donnell C.J. acknowledged that future cases would raise “difficult questions” about how to deal with costs where a party obtains some relief but loses on certain issues. He warned against a mechanistic “issue-by-issue balance sheet” approach:

“The reality [is] that a winning party often loses on some issues, and … it seems unlikely that the Oireachtas intended that once this occurs, the Court should be propelled into the process of interrogating a ‘balance sheet’ of ‘issues’ on which each side has won or lost.”

He referred to Leggatt J.’s judgment in Iraqi Civilians v Ministry of Defence [2018] EWHC 690 (QB), saying that the key question is whether there are:

“any big issues which have occupied a substantial amount of time and cost and were important in the proceedings on which the overall winner has lost”.

This approach reframes the costs inquiry away from micromanaging every pleaded issue, towards a focus on whether the winning party was unsuccessful on substantial, costly, and important issues.

Farrell J draws directly on this “big issues” test. She regards that type of situation as what Order 103 Rule 39(1)(c) contemplates when speaking of a party who is “partly successful” (para. 13). In other words, “partly successful” for the purposes of costs is not automatically triggered whenever any pleaded point does not succeed; rather, it is engaged when significant, resource-consuming issues are actually decided against the winning party.

3.2.2 Iraqi Civilians v Ministry of Defence [2018] EWHC 690 (QB)

Leggatt J.’s judgment in Iraqi Civilians is an influential English authority on costs in multi-issue litigation. While not binding in Ireland, it has been expressly endorsed by O’Donnell C.J. and now followed in practice by Farrell J.

The core idea, adopted here, is the “big issues” focus:

• Not every lost minor issue warrants a proportionate reduction in the winner’s costs.
• The court should look for major issues that:
  • occupied a substantial portion of time and cost; and
  • were materially important to the parties and to the outcome;
  and on which the winning party nevertheless failed.

Farrell J uses this to frame what “partly successful” must mean under Order 103 and s. 169 LSRA 2015.

3.2.3 Watchhouse Cross Shopping Centre Ltd v An Comisiún Pleanála [2025] IEHC 520

In Watchhouse Cross the High Court determined a number of grounds against the applicant at the substantive stage (para. 9). The exact terms of the costs order were agreed between the parties and handed into court. The important contrast with Palatine is:

• In Watchhouse, some issues were actually decided in the respondent’s favour.
• That is the context in which a “partly successful” applicant may properly face a reduced or apportioned costs order.

3.2.4 Ventaway Ltd v An Comisiún Pleanála [2025] IEHC 406

Similarly, in Ventaway, the court decided some grounds against the applicant (para. 9). Again, this stands in contrast to Palatine, where no ground was resolved adversely to the applicant.

Taken together, ESB v Good, Watchhouse and Ventaway establish the context against which Farrell J distinguishes the present case:

• Those are cases where the successful party did lose on identified, decided issues.
• Palatine is a case where no issue was decided in favour of the respondent at all.

3.3 Legal reasoning: what counts as being “wholly successful”?

3.3.1 The key interpretative step at para. 17

The core interpretative move appears in para. 17, where Farrell J states:

“I do not consider that section 169(1), which refers to ‘A party who is entirely successful in civil proceedings’ and ‘a party who is not successful in those proceedings’, is consistent with an interpretation that a party is entirely or wholly successful only if it succeeds on every point advanced or pursued, rather than every point determined by the Court.”

In essence, “entirely/wholly successful” is assessed by reference to:

• the outcome of the proceedings and the issues the court actually had to decide, not
• every argument or ground counsel chose to plead or maintain.

This leads to two key conclusions:

1. If the applicant obtains the relief sought (here, certiorari), and no ground is determined against it, then the applicant is “wholly” or “entirely” successful for the purposes of s. 169.
2. Unused or undetermined grounds do not, without more, convert a wholly successful party into a partly successful one.

3.3.2 Application to the facts (paras. 8–9 and 18)

The court emphasises that:

• The substantive relief sought was an order of certiorari (para. 8).
• The applicant advanced multiple grounds entitling it to that relief, but the court found it necessary to decide only core ground 4 to grant certiorari (para. 8).
• No other ground was determined in favour of the Commission (para. 17).

Given that:

“I consider that the Applicant was wholly successful in its application for certiorari, despite the fact that I found it necessary only to determine the issue raised in Core Ground 4.” (para. 18)

This is a clear and important statement: wholly successful refers to the success in obtaining the relief on every issue which the court actually decided — not on every issue pleaded.

3.3.3 Distinguishing “partly successful” cases (para. 13)

Farrell J interprets Order 103 Rule 39(1)(c) (“partly successful”) through the lens of the ESB v Good / Iraqi Civilians “big issues” approach (para. 13). She sees that sub-rule as addressing cases where:

• The applicant does obtain some relief; but
• There are significant issues — consuming substantial time and costs and important to the proceedings — that are decided against the applicant.

That is not the position in Palatine. Here:

• No issue was decided in favour of the Commission.
• The court simply declined to rule on the other grounds, considering it unnecessary.

Therefore, the kind of “part-success” envisaged by Order 103 Rule 39(1)(c) (as illuminated by ESB v Good) is absent.

3.3.4 Efficiency, incentives and the conduct of proceedings (paras. 19–21)

The judge goes on to discuss the policy and practical effects of the statutory and rules-based costs regime:

• Order 103 Rule 39 and ss. 168–169 LSRA 2015 “operate to incentivise, rather than disincentivise efficiencies” in how parties conduct proceedings (para. 19).
• Applicants can be penalised in costs (through reduced or apportioned costs) where they insist on running weak or excessive points and lose on them, even if they obtain relief overall (para. 19).
• Respondents can minimise exposure to costs by:
  • Conceding on a particular determinative issue at an early stage (which did not happen here); or
  • Seeking modularisation of proceedings in suitable cases (again, none of the parties did so here, para. 9).

Conversely, the judge issues a caution (para. 20):

“[I]t is open to the Court to take the view, in a particular case, that the manner in which the case had been advanced by a successful applicant, in particular by relying on excessive grounds, would justify departure from the usual rule that the costs follow the event.”

However, critically:

• The court is not required to determine every issue just for the purposes of making a nuanced costs order (para. 21).
• To do so would be an inefficient and undesirable use of judicial time and resources, particularly where proceedings might be resolved on a narrower basis.

This reinforces a principle familiar in public law: courts often decline to decide unnecessary issues, particularly once the principal relief can be granted — and they will not be pushed to decide them solely to justify a more granular costs order.

3.3.5 The avoidance of a “balance sheet” approach

Aligning with ESB v Good, Farrell J implicitly rejects any suggestion that courts should:

• list out each ground or issue;
• mark them as “won” or “lost”; and
• mathematically apportion costs based on a tally.

Instead, the approach is:

• Ask whether there were major, decided issues on which the winning party lost.
• If so, consider whether a proportionate and just reduction in costs is warranted, having regard to s. 169 LSRA 2015.
• If not — and especially if no issue was decided against the winning party — then the party is “wholly successful” and costs follow the event.

3.4 Impact and significance

3.4.1 Clarifying “wholly successful” vs “partly successful” in planning JR

This judgment gives concrete content to what “entirely” or “wholly” successful means in planning and environmental judicial review under s. 169 LSRA 2015 (and, by extension, Order 103 Rule 39).

The key clarification is:

• A party who wins the relief sought and has no issues decided against it is “wholly successful”, even if the court decides only one of several pleaded grounds and finds it unnecessary to deal with the others.
• “Partly successful” is reserved for cases where the applicant:
  • obtains some relief; but
  • loses on major, decided issues that consumed substantial time and costs.

This is an important counterweight to any attempt by respondents to argue that the mere existence of undetermined or unsuccessful arguments should trigger a “partly successful” classification and cost dilution.

3.4.2 Practical implications for applicants

• Applicants can plead multiple, alternative grounds without the automatic fear that, if they succeed on one ground and the court does not reach the others, they will be treated as only “partly successful”.
• However, applicants must still exercise discipline and proportionality in the grounds they choose to run:
  • Where they insist on advancing a large number of weak or unnecessary grounds that are expressly rejected, this can expose them to adverse costs consequences, notwithstanding overall success (para. 20).

3.4.3 Practical implications for respondents (including planning bodies)

• Planning authorities and other respondents are reminded that:
  • Defending every ground, including one that is clearly problematic, may increase their exposure to costs.
  • They can limit liability by timely concessions on clearly unsustainable issues (e.g. where there is an obvious error of law, like failure to give adequate reasons).
  • They can seek modularisation of proceedings to isolate preliminary or potentially determinative issues. Failure to seek such modularisation (as in Palatine) undermines later claims that costs should be limited to a single issue.
• This judgment may encourage more strategic and constructive engagement by public bodies in planning JR, including the greater use of concessions to avoid prolonged, multi-issue hearings where a clear error is identified.

3.4.4 Judicial economy and avoidance of unnecessary determinations

The judgment reinforces the principle that:

• Court time and resources should not be spent deciding superfluous or academic issues purely to calibrate a costs order (para. 21).
• Where the case can be resolved on a narrow ground, the courts will often do so, especially in judicial review.
• Parties should not expect a detailed issue-by-issue ruling solely for the purpose of arguing for a segmented costs order.

This buttresses the broader public law practice of minimalist decision-making where possible, particularly in planning and environmental review.

3.4.5 Transitional and future use of Order 103

Although Farrell J declines to decide whether Order 103 applies retrospectively in this case, she signals that:

• If the issue had to be resolved, it would be relevant that the parties had no opportunity to adjust their conduct in light of the new rules (para. 15).
• Going forward, parties will be on notice that:
  • Order 103 applies both to pre- and post-commencement proceedings (per Reg. 2); and
  • The classification between “unsuccessful”, “wholly successful” and “partly successful” will be informed by s. 169 LSRA 2015 and ESB v Good.

In this sense, Palatine gives early interpretative guidance on how Order 103 Rule 39 is to be understood, even if it does not definitively resolve every transitional question.

4. Complex Concepts Simplified

4.1 “Costs follow the event”

This is the traditional starting point for civil costs:

• The “event” is who wins or loses the case.
• The default rule (now reflected in s. 169 LSRA 2015) is that the losing party pays the winning party’s costs, unless the court orders otherwise.

What Palatine clarifies is how to decide who is the “winner” in complex, multi-issue litigation:

• If the applicant achieves the relief sought (certiorari) and no substantive issue is decided against it, it is the “entirely” or “wholly” successful party.

4.2 Certiorari

Certiorari is a form of judicial review order by which a court quashes a decision of a public body. Here:

• The applicant sought and obtained an order quashing the planning permission granted by the Board.
• This is a classic remedy in planning judicial review where legal error is found in the decision-making process.

4.3 Costs protection and Order 103

In many planning and environmental cases, EU law (via the Aarhus Convention) and domestic rules provide for a degree of “costs protection” so that individuals and community groups are not deterred from bringing environmental challenges by the risk of ruinous cost exposure.

Order 103 of the RSC:

• Regulates such planning and environmental proceedings.
• Introduces structured costs presumptions depending on whether an applicant is:
  • unsuccessful;
  • wholly successful; or
  • partly successful.
• Interacts with s. 169 LSRA 2015, which is the overarching statutory framework.

Palatine confirms that “wholly successful” in this special planning context must be interpreted consistently with “entirely successful” in s. 169 LSRA 2015.

4.4 Modularisation

“Modularisation” of proceedings means dividing a case into separate stages or “modules” so that:

• Certain threshold, preliminary, or potentially determinative issues are heard first.
• If the applicant wins or loses on those issues, some or all of the remaining issues may become unnecessary to litigate, saving time and costs.

In Palatine:

• Core grounds 6 and 7 were modularised.
• No application was made by any party to modularise any of the other core grounds (para. 9).

Farrell J notes (para. 9) that the Commission could have sought such modularisation or conceded the determinative ground, but did not. That reduces the force of any later argument that the applicant’s costs should be curtailed because multiple grounds were maintained.

4.5 Adjudication of costs

When the court orders that one party pay the “costs of the proceedings … to be adjudicated in default of agreement”, this means:

• The parties are expected to try to agree the quantum (amount) of costs between themselves.
• If they cannot agree, the costs are assessed by the Office of the Legal Costs Adjudicators under the LSRA 2015 (which replaced the old system of taxation of costs).

5. Conclusion

Palatine DAC v An Coimisiún Pleanála (No. 2) [2025] IEHC 607 is a significant costs ruling in the planning and environmental judicial review sphere. The judgment can be distilled into the following key propositions:

1. Definition of “wholly successful”: A party that obtains the relief sought and has no issues decided against it is “wholly” or “entirely” successful for the purposes of s. 169 LSRA 2015 and Order 103 RSC, even if:
   • multiple grounds were pleaded; and
   • the court only found it necessary to determine one.
2. “Partly successful” reserved for substantial lost issues: “Partly successful” (under Order 103 Rule 39(1)(c)) is engaged where a party:
   • obtains some relief; but
   • loses on major, decided issues that have consumed substantial time and cost.
   It is not triggered simply by the existence of undetermined grounds.
3. Rejection of “balance sheet” issue-by-issue costs accounting: Consistent with ESB v Good and Iraqi Civilians, the court declines a mechanical approach where every pleaded issue is scored as “won” or “lost” to calculate a costs apportionment.
4. Emphasis on efficiency and party conduct: Sections 168–169 LSRA 2015 and Order 103 RSC are seen as tools to incentivise efficient conduct:
   • Applicants may face reduced costs if they run excessive and weak grounds they lose on.
   • Respondents can and should consider concessions or modularisation where appropriate.
5. No need to decide unnecessary issues for costs: Courts will not be driven to determine every ground purely to justify a more nuanced costs order; economy of judicial decision-making remains a key principle.

On the facts, the applicant was held to be wholly successful and entitled to its full costs against the Commission, including reserved costs and the costs of written submissions, with no apportionment or reduction because other grounds were left undetermined.

For future planning and environmental litigation, Palatine (No. 2) provides a clear signal:

• Applicants who ultimately secure the quashing of a decision on any properly pleaded ground, without adverse determinations against them, can expect to be treated as wholly successful for costs purposes.
• Respondents who choose to defend all grounds without concession or modularisation cannot later rely on the multiplicity of grounds to argue for a drastic limitation of the applicant’s costs.

In that sense, this judgment is a significant contribution to the developing jurisprudence on costs in public law and planning judicial review in Ireland, and will likely be cited as an important authority on how to classify success and structure costs orders under the LSRA 2015 and the new planning/environment rules in Order 103.