By Ruth Mercer
The High Court has struck out a second legal challenge brought by Niall Byrne over the 2025 presidential election process, finding that it repeated issues already decided in earlier proceedings.
Mr Byrne had previously sued the Tánaiste, the Minister for Housing, Ireland and the Attorney General and sought, among other reliefs, to prevent the presidential election from proceeding. On 20 October 2025, Mr Justice Cregan dismissed that case after finding that the issues raised were either not justiciable or disclosed no reasonable cause of action.
Mr Byrne appealed that decision to the Court of Appeal and Supreme Court, with those appeals still pending when the present judgment was delivered. He also made unsuccessful applications in the High Court seeking to reopen the first proceedings before issuing a second case.
In the second action, Byrne again challenged an alleged directive issued by the Tánaiste on 6 September 2025 and argued that it unlawfully interfered with the presidential nomination process. He also sought a declaration that the Presidential Election Order was invalid as a consequence.
Mr Justice Cregan found that the new proceedings involved the same parties and, in substance, the same issues as the first case. He held that the claims were therefore res judicata, meaning they had already been judicially determined and could not be litigated again.
The court also found that attempting to re-litigate the same dispute amounted to an abuse of process and that the proceedings were bound to fail.
Even if the challenge to the Presidential Election Order were treated as a new argument, the judge held that it could not succeed in these proceedings. He said such a claim was not justiciable in the form advanced and that the Presidential Elections Act 1993 contains specific procedures for election challenges.
The proceedings were struck out. The judgment does not determine Byrne’s pending appeals from the October ruling.