Exceptional means exceptional – the strict deadline for challenging UK CMA merger decisions

The UK’s Competition Appeal Tribunal (CAT)’s recent judgment in Aramark Limited v Competition and Markets Authority is a sharp reminder that the four-week deadline for challenging a Competition and Markets Authority (CMA) merger decision is applied very strictly. The CAT will apply a restrictive approach to attempts to extend the deadline for “exceptional” reasons — the severity of the consequences for missing the deadline and a lack of prejudice to the regulator from a mis-calculation, will not be enough to turn back the clock.

Background

The dispute arose following the CMA’s January 2026 Final Report into Aramark’s 2025 completed acquisition of Entier Limited, which concluded that only a full divestiture of Entier’s UK business would address competition concerns. The decision had attracted widespread attention as it resulted in a noticeably tough enforcement outcome at a time when the CMA is seeking to demonstrate that its decisions do not undermine investment in the UK. Under Rule 25 of the CAT Rules, Aramark had four weeks to file an application for judicial review of the CMA’s decision.

Aramark’s legal team, applying a (later admitted to be erroneous) interpretation of Rule 112 governing the computation of time, believed the deadline was 5:00 pm on Friday, 13 February. Although they had initially planned to file a day “early”, on Thursday, 12 February, that plan slipped into Friday morning to accommodate last-minute comments from US-based management.

When the Notice of Application was finally sent at 12:02 pm on Friday, the CAT Registry declined to register it. The true deadline had expired at 5:00 pm the previous evening — some 19 hours earlier.

Aramark applied, retrospectively, for an extension of time to 13:00 on 13 February 2026. The CMA opposed the request.

The CAT’s judgment

The CAT refused the application. The power to extend time under Rule 25(3) is available only where the Tribunal is satisfied that the circumstances are exceptional — a deliberately high bar. In the CAT’s judgment, they were not.

Key reasoning

The computation of time. The CAT confirmed that Rule 112(3) determines the end date of the four-week period for Rule 25 purposes. Since the CMA’s Final Report was published on Thursday, 15 January 2026, the period ended with the expiry of Thursday, 12 February 2026. Aramark’s solicitors’ interpretation was wrong. James Wolffe KC, sitting as a single Chair of the Tribunal, noted he did not consider there to be "reasonable room for doubt" as to that effect and that the Tribunal’s published Guide to Proceedings states the position plainly. 

The ‘exceptional circumstances’ threshold. The CAT rejected each of Aramark’s arguments seeking to justify an extension of time:

• Good faith error on the rules.  Accepted as the underlying cause, but not treated as exceptional. The CAT observed that Aramark’s solicitors should, at least, have resolved any perceived ambiguity in the rules by filing before the earliest possible deadline.
• Departure from the internal plan. This compounded the error. Aramark’s own plan envisaged filing on 12 February, and there was no adequate explanation on the evidence for why that plan was abandoned — or whether any thought was given to the risk of doing so.
• Short extension/no prejudice to the CMA. This factor was given limited weight. Absence of specific prejudice to the CMA does not, of itself, advance the exceptional circumstances analysis, and the shortness of the extension required is “intrinsic to the nature of the error” rather than something exceptional about it. The CAT also noted that there would be arguable prejudice to the CMA and legal certainty if the deadline was extended and the CMA was obliged to defend the case.
• Severity of consequences. The CAT acknowledged — repeatedly — the severity for Aramark of losing the opportunity to challenge a divestment order. It nonetheless concluded that consequences of this kind are an inherent feature of any statutory time limit, not something that distinguishes this case from others.
• The surrogacy principle. Aramark argued that in circumstances where the error was entirely the solicitors' fault, Aramark was blameless, and damages would be an inadequate remedy, it would be unjust to impute the solicitors' mistake to the client. The CAT accepted the “surrogacy principle”, which attributes acts of legal counsel to their client, is not universal, but declined to depart from it here. Wolffe KC emphasised that merger proceedings are specialist cases invariably managed by external lawyers; if clients could routinely distance themselves from their lawyers’ procedural errors, the CAT’s time limits would be seriously undermined. He also found, on the evidence, that Aramark could not be said to be entirely blameless — the unexplained decision to accommodate late US management input and slip from the internal filing date was, at least in part, Aramark’s own conduct. 

Practical takeaways: avoiding disaster

The judgment serves as a manual for how to manage a CAT filing:

1. Diarise conservatively. The Guide to Proceedings expressly warns against waiting until the last day. This judgment illustrates exactly why. Had Aramark filed on 12 February as planned, the solicitors’ misreading of the CAT Rules would never have mattered.
2. Resolve any ambiguity in favour of earlier filing. Where there is any doubt about the computation of time — even a well-reasoned one — file against the earlier date. The CAT will not be sympathetic to a confident (but erroneous) interpretation.
3. The 5:00 pm rule is absolute: Rule 112(1) is unforgiving and requires deadlines to be met by 5.00pm UK time. As the Chair noted, leaving service to the final day “courts disaster” and leaves a party with a “limited claim on the indulgence of the court”.
4. Retrospective extensions are extremely difficult to obtain. Where the question is whether a failure to file on time should be excused, the bar is very high. Only truly “exceptional” circumstances will be taken into account.
5. Surrogacy arguments face an uphill struggle in commercial merger cases. Corporate entities with essentially economic interests will find it hard to claim any flexibility by seeking to distance themselves from mistakes made by their lawyers — particularly where the evidence does not clearly establish the client’s own blamelessness.

Conclusion

The deadline for bringing a challenge to a CMA merger decision has always been understood to be very strict.  This ruling reinforces that extensions to the deadline can only rarely be granted, where there are truly “exceptional” circumstances.  The fact that Aramark is now subject to a compulsory divestment order which it will not be able to challenge, and the delay in fling was less than 24-hours, did not convince the Tribunal to extend the deadline here.

The message is an old one, but this judgment restates it with some force: in CAT merger proceedings, the four-week clock is unforgiving — once the clock strikes 5:00 pm, the door doesn’t just close — it locks.