Following on from our previous article on the emerging role of the Competition Appeal Tribunal (CAT) in subsidy control, Bristol Airport v Welsh Ministers was another case we were watching closely for insight into how the CAT would interpret and apply the Subsidy Control Act 2022 (the Act). The CAT’s judgment of 7 April 2026 dismissed the challenge on all grounds.

This case was about a decision by the Welsh Government (the Respondent) to provide support to Cardiff Airport. Its neighbouring airport in England, Bristol Airport (the Applicant), was aggrieved by this and commenced the proceedings. 

The case is distinctive among subsidy control challenges in the CAT to date. It is the first in which both parties agreed that the measure in question was a subsidy. In earlier cases, disputes had focused on the threshold issue of whether a subsidy existed at all. (Even in this case, some uncertainty arose during the proceedings as to whether the measure was an individual subsidy or part of a wider subsidy scheme.)

The case followed closely the blueprint envisaged by the Act. The Welsh Government referred the proposed subsidy to the CMA’s Subsidy Advice Unit (SAU) for non‑binding advice on compliance with the subsidy control principles. That process gives a public authority an opportunity to reflect on and refine its decision‑making, while also creating a potential platform for a negatively affected third party to pursue a challenge before the CAT.

In other respects, however, the claim followed a now‑familiar pattern. Consistent with its approach in earlier cases, the CAT refused the Applicant permission to rely on expert evidence. The economic context which will be common to many subsidy disputes does not in itself justify departure from the normal approach to judicial reviews, where expert evidence is rare.

Grounds of challenge

The Applicant challenged the subsidy in three broad ways:

1. The Respondent has not properly addressed the financial position of Cardiff Airport in making the decision, contrary to the provisions of the Act in relation to the grant of subsidies to ailing or insolvent enterprises.
2. The Respondent has not properly addressed the subsidy control principles set out in the Act, which the Respondent was required to have regard to in making the decision.
3. The Respondent has failed to comply with or otherwise have regard to the provisions of the Act which deal specifically with subsidies to air carriers.

Each of these grounds raised points of interest in the judgment. However, the second ground – concerning compliance with the subsidy control principles – is likely to be of the widest relevance for future cases.

Challenges to the subsidy control principles

On this central issue, the CAT expressed concern about the precision of the Applicant’s challenge, noting that it had “at times been difficult to identify precisely what the nature of the challenge is and on what basis”. This was despite the Applicant apparently having been required to provide, and having provided, a detailed table setting out its objections to the application of each principle.

The CAT’s approach was summed up in a key passage of the judgment:

For the most part, the challenges fail simply because they do not in substance illustrate any irrationality but rather illustrate a difference of opinion about the weight to be given to matters which were obviously the subject of consideration by the Respondent. That is not a proper basis on which to mount a challenge in judicial review proceedings.

This passage underscores that subsidy control challenges are fundamentally judicial review proceedings. Disagreement with the weight given to competing considerations, absent irrationality or legal error, will not be sufficient.

Looking ahead

On the facts, the Welsh Government had clearly undertaken a careful and structured assessment of the relevant material. That disciplined approach significantly constrained the scope for a successful challenge and left the Applicant relying (as we commented in other contexts here and here) on the most difficult and least successful grounds of judicial review. The outcome was therefore unsurprising.

However, not all public authorities will be so well prepared. Potential applicants in future cases are likely to want to make greater use of pre‑action information requests. This is a mechanism which (as we commented on here based on our research) had been rarely used in the early years of the regime. Effective use will facilitate an assessment the robustness of a decision and to identify viable grounds of challenge before proceedings are issued.