THE EU’S TOP court has ruled that Dublin Airport’s controversial 32-million-passenger cap must be taken into account when allocating flight slots, even if it means airlines losing slots they previously held – but the Irish government can still ditch the cap if it wants to.

In a significant judgment delivered today, the Court of Justice of the European Union (CJEU) found that the passenger limit constitutes a “legal restriction” on the airport’s capacity.

The ruling is likely to increase pressure on the government to remove the cap as soon as possible, amid concerns that airlines could otherwise face reductions in flight slots at Dublin Airport.

The cap was introduced through planning permissions granted in 2007 and 2008 for the development of Terminal 2 and the extension of Terminal 1.

It limits the combined annual passenger numbers at the two terminals to 32 million, unless further planning permission is granted, and was imposed partly because of concerns about transport capacity around the airport.

Passenger numbers have grown considerably since then, prompting airlines and airport operator DAA to push for the cap to be lifted.

Climate activists have argued against lifting the cap on environmental grounds, saying it would lead to increased greenhouse gas emissions from flights at Dublin Airport, while some locals are worried about the impact in their area of the number of flights rising.

In 2024, the Irish Aviation Authority introduced seasonal passenger limits in an effort to ensure the airport complied with the planning restriction.

Several airlines, including Ryanair and Aer Lingus, challenged the decisions in the High Court.

The High Court subsequently referred questions about the application of EU aviation law to the European court.

In today’s judgment, the CJEU ruled that planning restrictions affecting an airport’s capacity must be considered when determining the number of available flight slots.

“Whether it relates to flow or capacity, that condition sets a legally binding limit on the number of passengers which that airport may accommodate,” the court stated.

It also rejected the suggestion that airlines are automatically entitled to retain take-off and landing slots they have previously used.

The court said EU rules give existing airlines priority when allocating slots, but do not confer “a right to maintain series of historic slots or a right to have them automatically renewed”.

It found that the passenger limit could, in exceptional circumstances, result in airlines losing slots they would otherwise have retained.

The court also ruled that historic flight slots do not constitute property rights under the EU Charter of Fundamental Rights because they are temporary.

Responding to the ruling, Ryanair called on the government to abolish the passenger cap, describing the restriction as “outdated” and “absurd”.

The airline argued that Dublin Airport’s second runway provides sufficient capacity for 60 million passengers annually, while claiming that passenger numbers are expected to exceed 36 million this year.

“The time for further dither and delay by Micheál Martin’s government is over,” Ryanair chief executive Michael O’Leary said.

“Dublin Airport and Irish tourism can enter a new age of growth and success, but only when this stupid cap is finally abolished.”

The DAA said in a statement this evening that the EU court judgment “brings much-needed clarity to the various regulatory regimes impacting aviation in Ireland”.

“The Irish government’s decisive action in passing legislation to address the passenger cap, together with daa’s €2 billion Infrastructure Application to expand and future-proof Dublin Airport’s capacity and facilities, is critical to supporting Ireland’s international connectivity, job creation and economic success,” a DAA spokesperson added.

A number of climate activist groups have welcomed the ruling. 

Sorcha Tunney, senior manager at climate change charity Opportunity Green, said that while the court’s ruling will not in itself prevent the Irish government from pursuing plans to remove Dublin Airport’s passenger cap, it “clarifies the legal significance of airport capacity constraints”.

“Removing the cap would enable increased airport activity, with significant implications for aviation emissions,” Tunney said.

“The government cannot ignore the climate consequences of that decision.

“Removing the cap without adequately addressing the resulting emissions could increase Ireland’s exposure to legal challenge under Article 8 of the European Convention on Human Rights (ECHR), which protects citizens’ fundamental rights,” Tunney added.

Transport Minister Darragh O’Brien is separately seeking to remove the cap, with legislation signed into law in July giving him the power to amend or revoke the restriction.

O’Brien has said he wants to remove the cap “as soon as possible”, although the process requires environmental assessments before an order can be made.

The case will now return to the Irish High Court.