The Supreme Court has ruled that Brendan Kirwan must remain liable for the costs awarded against him in the High Court and Court of Appeal, while each side will bear its own costs of his Supreme Court appeal.
The costs ruling, delivered on March 23, 2026, follows the Supreme Court's May 2025 judgment dismissing Kirwan's appeal in long-running litigation arising from a 2006 property transaction.
Kirwan's proceedings had ultimately been dismissed for inordinate and inexcusable delay. The High Court found in 2019 that he had allowed litigation to remain largely inactive for years, and the Court of Appeal upheld that result in 2022.
The Supreme Court also dismissed his appeal, but the case became significant beyond the individual dispute. A seven-judge court reconsidered the long-established Primor test governing when proceedings can be struck out for delay and adopted a stricter, more structured approach. The court described its 2025 decision as the most important ruling in this area since Primor itself.
That public-law significance affected the costs outcome.
The court said there was no reason to disturb the ordinary costs orders made below. Both sets of defendants had succeeded in having the proceedings dismissed under what was then established case law, so their High Court and Court of Appeal costs awards remain intact.
The position in the Supreme Court was different. The case had been reheard before an enlarged seven-judge panel, with the Attorney General invited to participate because of the wider importance of the legal issue.
The Supreme Court therefore made no order for its own costs, finding that it was reasonable for Kirwan to have the delay issue fully determined at that level. The Attorney General, who participated in an amicus-like role, was also directed to bear his own costs.