By Ruth Mercer
The Supreme Court has made no order as to the costs of Samuel Walsh's unsuccessful appeal against Mars Capital Finance Ireland DAC, finding that the case clarified complex legal issues with significance beyond the dispute itself.
The ruling, delivered on 24 March 2026, follows the Supreme Court's substantive judgment of 12 November 2025, when it dismissed Walsh's appeal from a High Court decision. The High Court had itself dismissed his appeal from a Circuit Court order granting relief to Mars.
Mars argued that, because it had been entirely successful at every level, the normal rule that costs follow the event should apply. Walsh accepted that this was the starting point but argued that the Supreme Court appeal raised unusually important and difficult questions concerning limitation law and the effect of a settlement agreement.
The Supreme Court agreed that the appeal involved issues of real complexity and general importance and that its substantive judgment provided clarification likely to assist parties in other cases. The court also accepted that this guidance could have practical value for Mars in comparable litigation.
Those features were sufficient to justify departing from the usual costs rule for the Supreme Court stage. The judges stressed, however, that this did not turn the proceedings into public-interest litigation or a formal test case. It was a case-specific exercise of the court's discretion under section 169 of the Legal Services Regulation Act 2015.
The position was different for the earlier proceedings. Walsh had lost in both the Circuit Court and High Court, and the Supreme Court found no sufficient reason to disturb the costs orders made there.
Mars therefore retains its entitlement to its Circuit Court and High Court costs, while neither side will recover the costs of the Supreme Court appeal. The underlying dismissal of Walsh's substantive appeal remains unchanged.