Byrne v Tanaiste and Ors [No. 2] (Approved)

Factual and Procedural Background

This is an ex tempore judgment delivered by Judge Cregan on 19 December 2025 concerning an application by the Defendants to strike out new proceedings issued by the Plaintiff. The Plaintiff had previously issued substantially identical proceedings in October 2025, which Judge Cregan determined on 20 October 2025 (Record Number 2025/5467P, [2025] IEHC 565) and in which the Court refused the reliefs sought and dismissed the proceedings on the grounds that the issues were not justiciable and/or failed to disclose a reasonable cause of action. The Plaintiff appealed that judgment to the Court of Appeal and the Supreme Court; those appeals remain pending. After the first judgment the Plaintiff made a series of ex parte applications to adduce further evidence and to re-enter the struck-out proceedings; those applications were unsuccessful. The Plaintiff then issued the second set of proceedings (the subject of this judgment), again seeking declarations and orders challenging the Presidential Election Order of 2025 and the lawfulness of a directive said to have been issued by the first-named Defendant on or about 6 September 2025.

Legal Issues Presented

1. Whether the Plaintiff's second set of proceedings are res judicata by reason of the earlier decision of this Court.
2. Whether the second proceedings are bound to fail or otherwise fail to disclose a reasonable cause of action.
3. Whether the second proceedings amount to an abuse of process.
4. Whether the reliefs sought (including declarations that the directive was unlawful and that the Presidential Election Order was vitiated) are justiciable.

Arguments of the Parties

Plaintiff's Arguments

• The Plaintiff sought declarations that a directive issued on or about 6 September 2025 was unlawful, ultra vires and unconstitutional, that the Presidential Election Order of 2025 was vitiated and void as a consequence, and declarations that the 2025 presidential election was unconstitutional in its procedure.
• The Plaintiff pointed to the relief at paragraph (ii) of the plenary summons (a declaration that the Presidential Election Order was vitiated) as the distinguishing point between the first and second proceedings.

Defendants' Arguments

• Attorney O'Neill submitted that the reliefs in the second proceedings are, in substance, identical to those in the first proceedings and that certain reliefs (paragraphs (v) and (vi) relating to staying an inauguration) are moot.
• Attorney Clarke, acting for Attorney Harris (in his capacity as leader of a political party), adopted Attorney O'Neill's submissions and made additional submissions to the same effect.
• The Defendants applied to strike out the second proceedings on grounds that they are res judicata, bound to fail, fail to disclose a reasonable cause of action and are an abuse of process.

Table of Precedents Cited

Court's Reasoning and Analysis

The Court's reasoning proceeded in several, explicit steps grounded in the material before it:

1. The Court compared the reliefs and issues in the first and second proceedings and concluded that, in substance, they are identical or substantially the same. The earlier judgment had decided the core question—whether the matters complained of were justiciable—and dismissed the first proceedings.
2. Given the same parties, the same subject matter and a decision on the merits in the earlier case, the second proceedings are res judicata.
3. The Court held that re‑litigation of the same issues constitutes an abuse of process; re‑hearing the same complaint is impermissible.
4. The Court further concluded that the second proceedings are bound to fail because they raise issues already decided as non‑justiciable in the earlier judgment.
5. Where the Plaintiff sought a formulation of the argument that the Presidential Election Order was vitiated by the Defendant's directive, the Court observed that this issue had been considered or touched upon in the first proceedings and rejected; in any event the Henderson v. Henderson principle barred re‑making arguments that should have been advanced earlier.
6. The Court noted statutory context cited in the earlier judgment (section 6 of the Presidential Elections Act, 1993, concerning the Presidential Election Order) and observed that procedures for certain types of challenges are set out in sections 55 and 58 of that Act, indicating that the relief sought at paragraph (ii) was not properly pursued in these proceedings.
7. The Court also accepted the Defendants' submission that certain sought reliefs (stays of inauguration and declarations about continuity) were moot.

Holding and Implications

STRUCK OUT

Holding: The Court struck out the Plaintiff's second set of proceedings on the grounds that they are res judicata, constitute an abuse of process and are bound to fail.

Implications: The direct effect is that the Plaintiff's second proceedings are dismissed and an order will be made to that effect. The opinion does not purport to create a new legal precedent beyond applying established principles (res judicata, abuse of process and the rule in Henderson v. Henderson) and does not discuss broader implications beyond the effect on these proceedings.