Finality in Possession Litigation: Plenary Proceedings Cannot Collaterally Attack a Concluded Summary Possession Order

1. Introduction

This decision arises out of long-running possession litigation concerning a Limerick property owned by Mr Denis Connaughton and charged as security for a loan originally advanced by Bank of Scotland (Ireland) Limited, later transferred to Bank of Scotland plc, and then assigned to Start Mortgages Designated Activity Company (“Start”).

Start obtained a Circuit Court possession order on 17 February 2023 (Record No. 2018/0090). Mr Connaughton appealed to the High Court, where Heslin J dismissed the appeal in an ex tempore judgment published as [2023] IEHC 364, and also refused discovery. Mr Connaughton then sought leave to appeal to the Supreme Court; leave was refused ([2023] IESCDET 135).

Notwithstanding those final outcomes, Mr Connaughton issued fresh plenary proceedings in May 2024 expressly seeking to “set aside” the Circuit Court possession proceedings and related steps. Start applied to strike out the plenary claim under the amended Order 19, Rule 28(1) of the Rules of the Superior Courts (as substituted by SI 456/2023).

The key issues were:

• whether the 2024 plenary action was an impermissible collateral attack on final court orders and thus an abuse of process;
• whether the claim was barred by res judicata and/or the rule in Henderson v Henderson;
• whether Start’s later transfer of its portfolio to Mars (and Mars’s substitution in the possession proceedings) affected maintainability of the plenary action;
• more broadly, whether a litigant can demand a “plenary hearing” after losing summary possession proceedings, by reframing or expanding arguments.

2. Summary of the Judgment

Mulcahy J struck out the plenary proceedings under Order 19, Rule 28(1), holding that the action had no prospect of success and “cannot succeed”. The Court found:

• the proceedings were a direct attempt to set aside or undermine final orders made in concluded possession proceedings and therefore amounted to an abuse of process;
• to the extent the action re-ran issues already decided (Start’s entitlement to possession, default, assignment, unfair terms arguments, Central Bank-related complaints), those issues were res judicata;
• to the extent the action sought to advance “new” arguments (e.g., overcharging calculations, or section 28(6) of the Supreme Court of Judicature (Ireland) Act 1877 notice of assignment points), they could and should have been raised in the earlier proceedings and were barred by Henderson v Henderson absent special circumstances (none were shown);
• Start’s assignment of the loan/charge to Mars and Mars’s substitution in the possession proceedings reinforced that the claim against Start was bound to fail, but—critically—the Court made clear this was not an invitation to sue Mars in fresh plenary proceedings, because any attempt to attack the possession order would still be abusive;
• if Mr Connaughton wished to challenge the 2025 substitution/execution order, the proper route was an appeal of that order, not a collateral plenary claim to set aside the earlier possession proceedings.

3. Analysis

3.1 Precedents Cited

A. Strike-out / dismissal jurisdiction (Order 19, Rule 28(1) and inherent jurisdiction)

The Court anchored its approach in the modern strike-out framework following the substitution of Order 19, Rule 28(1) by SI 456/2023. The amended rule expressly allows striking out where a claim: discloses no reasonable cause of action, amounts to an abuse of process, is bound to fail, or has no reasonable chance of succeeding.

Mulcahy J relied on Simons J’s observation in O'Malley v National Standards Authority of Ireland [2024] IEHC 500 that the amendment “erod[es] the previous distinction” between strike-out under the rules and dismissal under the inherent jurisdiction—signalling that courts can more directly address hopeless or abusive litigation within the rule itself.

The Court also adopted the structured summary in Beades v KBC Mortgage Finance Company [2025] IEHC 363 (Dignam J), which restates the “high threshold” and the constitutional caution attaching to strike-out: the default is trial, the jurisdiction is sparingly exercised, pleadings taken at “highwater mark”, and the moving party must show the plaintiff “cannot succeed” and cannot be rescued by amendment, discovery, or trial evidence.

Beades in turn cited a line of authority illustrating the settled nature of the jurisdiction: Barry v Buckley [1981] IR 306, Salthill Properties Limited v Royal Bank of Scotland plc [2009] IEHC 207, Lopes v Minister for Justice, Equality and Law Reform [2014] IESC 21, Keohane v Hynes [2014] IESC 66, Clarington Developments Limited v HCC International Insurance Company plc [2019] IEHC 630, Kearney v Bank of Scotland [2020] IECA 92, and the more recent Court of Appeal statements in Scotchstone Capital Fund Ltd & anor v Ireland & anor [2022] IECA 23 and McAndrew v Launceston Property Finance DAC & anor [2023] IECA 43.

Importantly, Mulcahy J applied these principles not to decide contested merits (e.g., whether overcharging occurred), but to decide whether the very bringing of the plenary action was procedurally impermissible given the finality of the earlier orders.

B. Collateral attack as abuse of process

The central authority was Mullaney v Ireland [2023] IECA 195, where the Court of Appeal held it is an abuse to bring proceedings whose “purpose and effect” is an impermissible collateral attack on “valid, final, un-appealed Orders”. Mulcahy J treated Mr Connaughton’s express pleading—seeking “a set aside of the entire Circuit matter”—and his affidavits identifying the “Purpose of this Plenary Action” as dispositive of purpose and effect.

The Court reinforced that this principle is frequently applied in response to a “proliferation” of such litigation, citing examples: Scanlan v Danske Bank [2023] IECA 102, Tucker v Tailte Éireann [2025] IECA 80, Masterson v Pepper Finance [2024] IEHC 547, Hogan v Tanager [2024] IEHC 739, KBC Bank v Smith [2025] IEHC 481, and again Beades v KBC Mortgage Bank.

The judgment’s practical message is that courts will look past drafting or asserted “new issues” and focus on whether the proceedings functionally seek to undo final orders.

C. Res judicata and Henderson v Henderson (“could and should”)

Mulcahy J invoked two related finality doctrines:

• Res judicata: issues finally determined cannot be re-litigated.
• Henderson v Henderson: issues that were not raised earlier but could and should have been raised are barred, absent special circumstances.

For the modern Irish formulation, the Court relied on Munnelly v Hassett and Ors [2023] IESC 29, where O’Donnell CJ endorsed:

• the flexible, non-dogmatic approach emphasised in AA v Medical Council [2003] IESC 70, [2003] 4 IR 302;
• McDonald J’s two-stage “could and should” test from George and George v. AVA Trade (EU) Ltd. [2019] IEHC 187, including the “special circumstances” escape valve.

Applying that framework, Mulcahy J held that any “new” points (including section 28(6) Judicature Act 1877 notice arguments and the overcharging narrative) were matters that could and should have been raised in the possession proceedings and no special circumstances were advanced to justify the second action.

D. Mortgage possession context: title/assignment, registration, unfair terms, securitisation

Although Mulcahy J declined to engage with the merits, the judgment is situated against determinations already made in the earlier proceedings and the authorities referenced there:

• Bank of Ireland v Cody [2021] 2 IR 382, [2021] IESC 26: referenced as the “leading case” on the proofs required in possession litigation; Heslin J had applied the relevant principles in the appeal ([2023] IEHC 364), and the Supreme Court determination observed the High Court had applied “standard principles”.
• Start Mortgages DAC v Ryan [2021] IEHC 719 and Permanent TSB plc v Davis [2019] IEHC 184: cited by Heslin J on the Unfair Contract Terms Directive, particularly the exclusion of “core terms” from assessment under Article 4(2) where in plain intelligible language; Heslin J found only core terms were at issue.
• Wellstead v Judge White & Ors [2011] IEHC 438: cited here to note the repeated rejection of “securitisation deprives the lender of enforcement rights” arguments.
• Mars Capital Finance v Temple [2023] IEHC 94: invoked by the plaintiff as a reason to “re-open” the mortgage deed issues; Mulcahy J treated such re-opening as impermissible given the finality of the concluded possession litigation.

3.2 Legal Reasoning

A. The Court identified the true character of the claim: a collateral set-aside

The strike-out succeeded largely because the plaintiff did not merely plead ancillary relief; he pleaded a direct set-aside of “the entire Circuit matter”. His affidavits expressly stated his purpose was to “establish the true state” of assignments and privity, in order to undermine enforceability. Mulcahy J treated the pleaded and sworn objective as conclusive of the proceedings’ “purpose and effect” within the meaning of Mullaney v Ireland [2023] IECA 195.

B. “Summary” disposal does not create an entitlement to a later plenary re-run

A core practical point of the judgment is the rejection of Mr Connaughton’s belief that, because the earlier possession proceedings were resolved summarily, he retained some residual entitlement to a plenary trial of entitlement to possession. Mulcahy J held the opposite: once the summary process results in final orders (and appeals are exhausted), a litigant cannot institute plenary proceedings to develop, expand, or reframe arguments aimed at overturning the result.

C. Finality applied through three overlapping routes

The Court provided three mutually reinforcing bases for dismissal:

• Abuse of process: the claim was an impermissible collateral attack on final orders.
• Res judicata: entitlement to possession and related issues had already been decided.
• Henderson v Henderson: any purportedly new points could and should have been raised earlier and were not excused by special circumstances.

This tripartite reasoning is significant: it prevents litigants from avoiding dismissal by recasting the same complaint as “new evidence”, “new legal arguments”, or “need for discovery”.

D. The Start-to-Mars transfer did not assist the plaintiff

Start established (and the Court accepted) that it had transferred and assigned its rights to Mars, and Mars had been substituted in the possession proceedings with leave to execute. Mulcahy J held that this made much of the claim against Start “bound to fail” as Start no longer had an interest in the possession order attacked. However, the Court explicitly cautioned that this was not an invitation to:

• issue fresh proceedings against Mars to attack the possession order; or
• amend these proceedings to join Mars.

The Court also clarified proper procedural routing: if there was a complaint about the 2025 substitution/execution order, the remedy lay in an appeal of that order—not collateral plenary litigation.

E. Refusal to adjudicate the merits was principled

Mulcahy J concluded that, having found an impermissible set-aside attempt, it was “not appropriate” to engage with the merits. This reflects a procedural discipline: courts avoid issuing advisory opinions on barred claims and avoid creating confusion by discussing merits where the litigation vehicle is abusive or precluded.

3.3 Impact

A. Reinforced finality in mortgage possession litigation

The judgment strengthens a clear line of recent Irish authority that prohibits borrowers from using a second set of proceedings (often plenary, often discovery-driven) to undermine concluded possession orders. It underscores that finality applies even where the original determination was “summary” in form.

B. Practical effect of the amended Order 19, Rule 28(1)

In relying on O'Malley v National Standards Authority of Ireland [2024] IEHC 500, the decision illustrates how the amended rule supports more straightforward case management against collateral attacks and hopeless claims, without elaborate debate as to whether the court is acting under the rules or its inherent jurisdiction.

C. Clear guidance on “new arguments” and “new evidence” after final orders

The Court’s application of Munnelly v Hassett and Ors [2023] IESC 29 signals that:

• post-judgment “fresh” points (e.g., accounting reports suggesting overcharging) will often be treated as matters that should have been advanced in the original proceedings;
• the “special circumstances” exception exists but requires a concrete explanation—mere dissatisfaction with the earlier outcome or a desire for discovery will not suffice.

D. Containment of securitisation and peripheral-compliance arguments

By citing Wellstead v Judge White & Ors [2011] IEHC 438, the Court reaffirmed that securitisation does not, without more, deprive a lender/assignee of enforcement rights—helping to limit repetitive deployment of that contention. The judgment likewise indicates that GDPR complaints or Central Bank-authorisation disputes, even if arguable in another forum, will not ordinarily provide a route to set aside a possession order through collateral proceedings.

4. Complex Concepts Simplified

• “Strike out” under Order 19, Rule 28(1): A procedure allowing the court to end a claim early where it is legally hopeless, abusive, or has no real chance of success—without a full trial.
• “Abuse of process” / “collateral attack”: Using new proceedings to undermine or overturn a final order made in earlier proceedings (instead of using the proper appeal route). Courts prevent this to protect finality and orderly justice.
• Res judicata: Once a court has finally decided an issue between parties, it cannot be re-litigated in later proceedings.
• Henderson v Henderson rule: Even if an issue was not actually argued in the first case, it may still be barred later if it could and should have been raised then—unless special circumstances justify the omission.
• “Summary” vs “plenary” proceedings: Summary procedures decide whether there is an arguable defence requiring a full trial. If the court determines there is none and makes final orders (and appeals are exhausted), a party cannot demand a “plenary re-run” simply by starting a new action.
• Substitution of a party (Start → Mars): Where a lender’s rights are assigned, the assignee can be substituted into existing proceedings. Challenges to that substitution/execution step generally must be taken by appeal within that procedural track, not by separate proceedings attacking the original possession order.

5. Conclusion

Connaughton v Start Mortgages Designated Activity Company (Approved) [2026] IEHC 164 is a firm restatement of litigation finality in the possession context. Mulcahy J confirmed that a borrower who has lost possession proceedings (including on appeal and after refusal of Supreme Court leave) cannot initiate plenary proceedings to set aside the earlier case, to seek discovery, or to advance re-packaged or newly devised objections to title, assignment, default, or regulatory compliance.

The judgment consolidates the interplay between Order 19, Rule 28(1), abuse of process principles (notably Mullaney v Ireland [2023] IECA 195), and the twin finality doctrines of res judicata and Henderson v Henderson as modernised by Munnelly v Hassett and Ors [2023] IESC 29. Its significance lies less in mortgage law substance and more in procedural discipline: once final orders exist, the court system will not permit collateral plenary litigation as a substitute for an appeal.