Digital Platform Follow-on Litigation: Brexit Binding Effect and the DMCCA 2024 Trajectory
In short: Digital platform follow-on litigation in the UK pivots on a date many readers know as “full Brexit”. At 11pm on 31 December 2020 the UK formally left the EU competition regime; lawyers call that moment “IP completion day”. Section 58A of the Competition Act 1998, recast by the Brexit statutory instruments SI 2019/93 and SI 2020/1343, draws the line at that date. European Commission infringement decisions made before IP completion day remain binding on UK courts and the Competition Appeal Tribunal. Later Commission decisions bind UK courts only where the Commission was already handling the case at the end of the transition period. The Digital Markets, Competition and Consumers Act 2024 now adds a separate UK enforcement track.
The Stage 1 trial in the Google Shopping follow-on damages proceedings, case managed together before the Competition Appeal Tribunal commenced on 22 June 2026, with a time estimate of five weeks and one week in reserve. These are among the most prominent digital platform follow-on litigation proceedings to have come before a UK tribunal. They put a spotlight on three rules that practitioners advising on competition damages and digital regulation should hold clearly in mind. The first is the post-Brexit form of section 58A of the Competition Act 1998, which decides when an infringement decision is binding on UK courts and the Tribunal in a follow-on damages claim. The second is the way two Brexit-era statutory instruments, SI 2019/93 and SI 2020/1343, drew the line at the end of the transition period (the moment commonly known as “full Brexit”, and as “IP completion day” in the legal drafting), which took effect at 11pm on 31 December 2020. The third is the new digital markets enforcement regime under Part 1 of the Digital Markets, Competition and Consumers Act 2024, which is starting to produce its first designations and commitments.
The Commission Decision and the Route to a UK Damages Trial
On 27 June 2017, the European Commission issued Decision C(2017) 4444 final in Case AT.39740, finding that Google had positioned and displayed its own comparison shopping service more favourably in its general search results pages than competing comparison shopping services, in breach of Article 102 TFEU and Article 54 of the EEA Agreement. The Commission imposed a fine of just over €2.42 billion. Google brought an annulment action under Article 263 TFEU. On 10 November 2021 the General Court gave judgment in Case T-612/17. It annulled Article 1 of the decision in so far only as the Commission had found an infringement in the 13 national markets for general search services on the basis of anticompetitive effects in those markets, and it dismissed the action as to the remainder. The finding that survives, and the one on which the UK claims are built, is the abuse of a dominant position on the national markets for comparison shopping services, upheld at paragraph 596. The Commission did not appeal the annulment. Google appealed to the Court of Justice, which, sitting as a Grand Chamber, dismissed the appeal in Case C-48/22 P on 10 September 2024.
Four sets of damages claims by operators of comparison shopping services are case managed together before the Tribunal, under case numbers 1424/5/7/21, 1589/5/7/23, 1596/5/7/23 and 1636/5/7/24. Foundem began in the High Court on 22 June 2012, Kelkoo on 23 December 2015 and Connexity on 4 October 2017, and each claim was later transferred to the Tribunal. The Connexity claims settled and were withdrawn by order of 11 February 2026. The Stage 1 trial commenced on 22 June 2026. Foundem settled during that trial and its proceedings were withdrawn by order of 27 July 2026. The Tribunal’s case records show no withdrawal in the Kelkoo or Whitewater proceedings, and a further hearing is listed in the Kelkoo proceedings for 11 September 2026.
Section 58A After IP Completion Day
The status of the Commission’s 2017 decision in UK follow-on damages proceedings turns on section 58A of the Competition Act 1998. The current section binds the court and the Tribunal to an infringement decision once it has become final, and defines an infringement decision for that purpose by reference to section 47A(6).
Before IP completion day, section 58A(4) extended the binding effect to relevant Commission decisions. That subsection was omitted by regulation 20 of the Competition (Amendment etc.) (EU Exit) Regulations 2019 (SI 2019/93). The omission, together with consequential amendments across the Competition Act 1998 and the Enterprise Act 2002, was timed to take effect on IP completion day (31 December 2020), the original “exit day” references in the 2019 Regulations having been replaced with “IP completion day” by the Competition (Amendment etc.) (EU Exit) Regulations 2020 (SI 2020/1343).
The transitional and saving provisions in Schedule 4 to SI 2019/93, as amended by SI 2020/1343, preserve the binding effect of European Commission infringement decisions made before IP completion day in respect of conduct occurring before that date. The 2020 Regulations align with Article 92 of the EU Withdrawal Agreement, which lets the European Commission finish work it had already started on a case at the end of the transition period. Where the Commission issues an infringement decision in such an already-running case after IP completion day, that decision can still found a follow-on damages claim in the UK. Decisions issued by the Commission in cases opened after IP completion day do not attract section 58A binding effect.
Decision AT.39740, made on 27 June 2017, sits squarely within the pre-IP completion day window and therefore retains binding effect for the purposes of UK follow-on damages claims arising out of the conduct it addressed. What the binding effect mechanism does not resolve is the live legal terrain at trial: the relevant counterfactual, the geographic and product market scope of the abuse on UK national markets, causation and quantum. Those questions were before the Tribunal at the Stage 1 trial, and the rest fall to later stages of the proceedings.
How far the binding effect reaches was itself tried as a preliminary issue in these proceedings. In the preliminary issue judgment of 9 July 2025, [2025] CAT 39, the Tribunal determined which recitals of the Commission’s decision bind it and what those recitals mean. It rejected Google’s proposed division of the decision’s findings into first, second and third order findings, holding at paragraph 30 that the taxonomy was artificial and found no support in EU case law, and at paragraph 31 that the correct approach is to apply the tests set out in its earlier decision in Trucks case by case to each disputed finding: whether the finding is necessary to clarify ambiguity, whether it is necessary to support the decision, and whether it would be appealable alone or together with other findings. The Tribunal recognised at paragraph 32 that this is likely to mean a significant number of recitals bind the national court, and it appended to the judgment a list of every recital in the decision with its status. Anyone advising on a follow-on claim built on a Commission decision should start with that appendix, because it states how much of the decision comes across as given.
The Stage 1 Trial and the Recent Scope Ruling
On 13 January 2026, in Kelkoo.com (UK) Limited & Others v Google UK Limited & Others [2026] CAT 3, the Tribunal ruled on the scope of the Stage 1 trial. The scope of the Stage 1 trial had been fixed by an order of 26 March 2024, varied on 20 December 2024. As the Tribunal recorded at paragraph 1 of the ruling, that order directs the trial to determine whether Google abused its dominant position “on the assumption that the relevant search markets were and are those defined by the European Commission in the Google Shopping Decision and that Google was and remains dominant on the said relevant markets as the Claimants allege”, and to determine the appropriate counterfactual. Dominance is therefore assumed at Stage 1 rather than in issue, and the Tribunal recorded at paragraph 12 that Google sought no variation to the first aspect, the question of abuse and its duration. What Google asked the Tribunal to remove was the counterfactual for the post-decision period, notified by letter of 18 December 2025. The Tribunal rejected that application at paragraph 27, finding at paragraph 26 that no material change of circumstances was relied on which could justify so late a change of course.
For practitioners advising on digital platform follow-on litigation, the procedural significance of the ruling lies in the way that case management commitments are taken to operate in complex damages litigation: once the parameters of a phased trial have been settled, an application to vary them late in the timetable will be assessed against the case management history and the proximity of trial. That is a procedural observation, not a comment on the substantive merits, which were argued at the Stage 1 trial.
The DMCCA 2024 Sits Alongside the Section 58A Regime
The Google Shopping damages claims run under the pre-DMCCA regime, but the Digital Markets, Competition and Consumers Act 2024 (DMCCA 2024) is starting to shape the landscape for digital platform regulation in the UK. Part 1 of the DMCCA 2024 came into force on 1 January 2025. The Digital Markets Unit within the CMA designated Google and Apple as having strategic market status (SMS) in respect of their mobile platforms on 22 October 2025, and the first commitments under the regime were accepted on 1 April 2026. We discussed those commitments in our earlier piece on the first DMCCA 2024 commitments from Apple and Google.
Commitments accepted under the DMCCA 2024 are not infringement decisions within section 47A(6) of the Competition Act 1998. They do not in themselves generate follow-on damages liability. The DMCCA 2024 and the Competition Act 1998 are nevertheless not mutually exclusive. Where an SMS-designated firm receives a Chapter II infringement decision from the CMA in respect of the same conduct, that decision attracts section 58A binding effect in the same way as any other UK infringement decision. Practitioners advising digital platform operators will want to track the SMS investigation pipeline alongside the existing Chapter II workstreams.
Relevance for Telecoms Operators
Although the Google Shopping proceedings concern comparison shopping services, the structural points reach telecoms operators directly. Telecoms businesses that depend on search placement, advertising infrastructure or app store distribution sit in the same digital ecosystem that the Stage 1 trial examined. Ofcom holds concurrent powers with the CMA under the Competition Act 1998 in respect of electronic communications networks and services, and an Ofcom infringement decision in that sector attracts section 58A binding effect in follow-on proceedings on the same footing as a CMA decision.
As we noted in our analysis of the proposed EU Merger Guidelines and their implications for telecoms, the convergence of digital and physical infrastructure has placed competition due diligence on platform conduct firmly within the scope of standard transaction legal advice. The post-Brexit binding effect regime, the scope of follow-on damages claims and the DMCCA 2024 enforcement pipeline are part of the legal due diligence landscape for operators and their advisers. For support on transaction risk assessments that involve digital platform competition exposure, see our deal structuring and negotiation page.
Viewpoint
The Brexit transitional binding effect regime is rarely the subject of practitioner attention in its own right. It tends to be folded into broader Brexit narratives. The Google Shopping proceedings are a useful reminder that the regime is doing real work: it allocates which European Commission decisions UK courts and the Tribunal must accept as binding, which fall outside that mechanism, and which sit in the limited continued competence pathway under Article 92 of the Withdrawal Agreement. Any practitioner advising on follow-on damages exposure in respect of conduct that straddles IP completion day needs to walk through that allocation step with care, since it determines the evidential starting point for any UK proceedings.
The DMCCA 2024 trajectory adds a forward-looking dimension. The Google Shopping timeline runs from conduct in 2008 through a 2017 decision, EU appellate proceedings concluded in 2024 and a UK damages trial in 2026. Quantum in digital platform follow-on litigation accumulates over years, and the trajectory of UK enforcement under the DMCCA 2024, while still at an early stage, points toward similar long timelines for any future follow-on damages exposure. Compliance investment now, integrated into existing competition law programmes, is proportionate to that exposure profile. Litigation teams running follow-on damages claims often need that regulatory expertise brought in as disputes co-counsel.
Rob Bratby advises digital platform operators, comparison shopping services and telecoms operators on competition law compliance and follow-on damages risk. For specific advice on digital platform follow-on litigation exposure or regulatory due diligence in the context of a transaction, contact Rob at rob@bratby.law or visit the contact page.
Correction, 19 August 2026: this post previously said that the General Court dismissed the appeal in Case T-612/17, and that the order fixing the scope of the Stage 1 trial identified dominance, alongside abuse, as a question for that trial. Both were wrong. The correct position is that the proceedings in Case T-612/17 were an annulment action under Article 263 TFEU, in which the General Court annulled Article 1 of Commission Decision C(2017) 4444 final in so far only as the Commission had found an infringement in the 13 national markets for general search services, and dismissed the action as to the remainder; and that the March 2024 Order proceeds on the assumption that Google was and remains dominant, with no variation sought to that aspect. Verified against the operative part of the judgment in Case T-612/17 and paragraph 596 of it, and against [2026] CAT 3 at paragraphs 1 and 12. The post has also been updated to record the preliminary issue judgment [2025] CAT 39 and the course of the Stage 1 trial.
