15 April 2024

Hunter V Hammond - CAT Determines Carriage Dispute As A Preliminary Issue

Travers Smith LLP


It’s not just law at Travers Smith. Our clients’ business is our business. Independent and bound only by our clients’ ambitions, we are wherever they need us to be. We focus on key areas of work where we are genuinely market leading. If it’s hard – ask Travers Smith.
On 5 February 2024, for the first time, the Competition Appeal Tribunal decided on a "carriage dispute", between two competing proposed class representatives, as a preliminary issue independent of certification.
UK Antitrust/Competition Law
To print this article, all you need is to be registered or login on

On 5 February 2024, for the first time, the Competition Appeal Tribunal (the "CAT") decided on a "carriage dispute", between two competing proposed class representatives ("PCRs"), as a preliminary issue independent of certification.1 The CAT made clear that unless there are special reasons why the carriage and certification issues should be heard together, deciding carriage disputes as a preliminary issue will be the preferred and automatic approach going forward. In its judgment, the CAT also provided helpful guidance on how such carriage disputes are to be determined in future cases.


The two PCRs, Ms Julie Hunter and Mr Robert Hammond, each filed applications for an opt-out collective proceedings order ("CPO"). Ms Hunter's application was filed on 15 November 2022 and Mr Hammond's on 7 June 2023 (the claim periods and the amounts being claimed by each PCR differ). Both applications involve stand-alone claims which allege abuse of a dominant position by Amazon in connection with the "Buy Box" function on its online market, and the related Featured Merchant Algorithm, which Amazon uses to select the "Featured Offer" featured in the Buy Box. The PCRs contend that the Buy Box/algorithm promote Amazon's own offers over those of independent traders. The applications must be brought as standalone claims as both the European Commission and the Competition and Markets Authority have conducted investigations into the operation by Amazon of the Buy Box and Featured Merchant Algorithm without a formal finding of infringement.

The applications were deemed sufficiently similar due to the similarity of the allegations and the existence of overlapping class members, such that it was not possible for the CAT to make an opt-out collective proceedings order in respect of both claims. Following the experience of the CAT in Evans v Barclays Bank plc,2 where carriage and certification were "rolled up" into a single hearing which increased costs and delay, the Tribunal ordered (and the parties agreed) that the carriage dispute should be determined as a preliminary issue.3


The CAT was required to determine which of the PCRs was most suitable to act as the proposed class representative for the purposes of Rule 78(2)(c) of the CAT Rules and, consequentially, proceed to a certification hearing.

The CAT stressed that its Ruling, which addressed matters relating to the expert methodology, was limited to the question of carriage and would not affect the future consideration of these matters at the certification stage.


In reaching its decision on the carriage dispute, the CAT noted the guidance set out in the Court of Appeal's judgment in Evans v Barclays Bank plc:4

  1. The CAT should apply a test of "suitability" when considering each application and the discretion of the CAT in doing so is broad and multifaceted.
  2. The CAT is expert at how proceedings play out at the "nuts and bolts" level and can form a view on the weight to be attached to the various considerations.
  3. The CAT may decide on carriage without the need to take account of the merits of either case.
  4. The fact that one PCR merely has a broader claim than the other is not an indication that that claim is preferable.
  5. The question of which claim was the first to file is largely an irrelevant factor.

With this guidance in mind, the CAT considered that the "key differentiator" between the two applications was the expert evidence which had been adduced for the purposes of demonstrating that the applications met the Pro-Sys5 test in the sense that the proposed expert methodologies offered a "realistic prospect of establishing loss on a class wide basis". Indeed, central to the CAT's assessment as to which application was more suitable were the methodologies proposed by each PCR in relation to: (i) the proof of the abuse; and (ii) the quantification of the overall loss suffered by the consumers.

While each party's expert had successfully cast doubt on the other's methodology, neither had successfully persuaded the CAT that the other's was bound to fail at certification.

In deciding between the two rival methodologies, the CAT formulated a test by way of two key (interrelated) questions, namely:

  1. Which methodology was "clearly and distinctly" better suited at articulating and resolving the claims that the PCRs wish to bring.
  2. Whether there was a difference in the practical workability of the methodologies and, taken at its most extreme, whether it can be fairly said that one or the other of them simply "will not work".

In addressing the first question, the CAT determined that the methodology of Mr Hammond's expert is better suited to resolving the claim as the proposed counterfactual which involves re-running the algorithms without the abuses as alleged, is more closely aligned to the alleged abuse. In contrast, the CAT viewed Ms Hunter's expert's methodology (which sought to ascertain consumer preferences for the purposes of establishing an appropriate counterfactual), as not aligning closely enough with the "true counterfactual" (i.e. the operation of Amazon's algorithm without the alleged abuse).

As to the second question, in determining the practical workability of Mr Hammond's expert's methodology, the CAT was satisfied it was "sufficiently workable" because it was clear from the methodology that the expert had considered the difficulties and how they could be overcome. Further, while Ms Hunter's expert expressed scepticism in regard to Mr Hammond's expert's methodology, Ms Hunter's expert stopped "well short" of saying that Mr Hammond's expert's methodology was unworkable.

The CAT therefore ruled that Mr Hammond was most suitable to act as the proposed class representative and he may therefore proceed to the certification stage.6

While the CAT considered the issues of the differing class definitions, differing claim periods and the time at which each of the applications were filed, the CAT did not attach weight to these considerations for the purposes of determining the carriage dispute.

As to Ms Hunter, although the CAT ruled in favour of Mr Hammond, it decided to stay her application on the basis that it was "well put together" and has "simply come second in a hard-fought race." In the event Mr Hammond's application for certification fails or is otherwise revoked, the stay on Ms Hunter's application could be lifted and her application could proceed to certification.

The CAT did, however, stress that, in the case of a "hopeless" application, an application that lost on the issue of carriage ought to be dismissed.

Key Takeaways

While hearing the carriage dispute as a preliminary issue in advance of certification may require a "degree of rough and readiness about the exercise", as the Court of Appeal noted in Evans v Barclays Bank plc "the CAT, armed with its rapidly growing expertise in the area will know what sorts of facts and matters are relevant".

While the CAT stressed that in hearing a carriage dispute as a preliminary issue, it does not want to trespass into issues that would normally be dealt with at certification, the fact that a key focus in this carriage dispute (and perhaps any carriage dispute) will be the relative merits of the expert methodologies necessarily means that the methodological issues that will be at the heart of the certification hearing will be trailed in the carriage dispute.

Similarly to other cases we have seen before the CAT in recent times7, in this judgment, the CAT again emphasised its willingness to take an interventionist and "likely quite intrusive" approach to case management to ensure the workability of a methodology and co-operation between the PCR and the defendant's expert.

The CAT's decision to stay (as opposed to dismiss) Ms Hunter's application will no doubt be of concern to Amazon and any other proposed respondent who finds itself facing multiple applications for CPOs. Defeating the preferred application at certification may simply mean that the proposed respondent must then contend with the runner up, causing prolonged uncertainty, increased costs and lasting disruption to the business. The CAT was clear that unless an application is deemed "hopeless", it will not be dismissed, which is a very low bar to set given the significant implications for any proposed respondent facing multiple applications for CPOs.

The potential implications of this approach need to be seen also in the light of the CAT's current practice of 'giving PCRs another go', which has seen a number of claims not pass the certification test but, rather than being dismissed, instead given a period of time to address the CAT's concerns before a further hearing.8 A PCR unsuccessful at the carriage stage might therefore stay on 'life support' for some time. Were it ever to emerge from the stay, real questions must then be asked as to the purpose of a further certification hearing, in circumstances where the preferred CPO had failed to achieve certification on (at least) two occasions (assuming the preferred CPO is not dismissed at the (first) certification hearing and is given 'another go'). Where the stayed CPO was presumably a weaker case, the prospects of it then succeeding might well be very low, unless radical surgery had been performed in the intervening period. When one considers this trend in conjunction with the low bar set by the CAT as to the staying of unsuccessful parties in carriage disputes, a somewhat bleak picture is painted for respondents who are effectively staring down at what must appear (and may well develop into) a never ending tunnel of costly and disruptive certification battles without much clarity or hope as to how and when it will come to an end (provided there remains any will on the side of the CPOs). This is an area which may well require the CAT to give further thought to, not least to reduce their own, already significant and ever expanding, workload.

In the event that the CAT does indeed reconsider the low threshold that has been set as to the staying of unsuccessful CPO applications in carriage disputes, then there might be merit in "rolling up" the carriage and certification hearings into one as, although it may increase costs in the short-term, it does have the advantage in bringing some finality to the issue of two competing CPOs. However, it appears for now that the clear preference of the CAT moving forward is to determine the carriage dispute in advance of any certification hearing, albeit losing the carriage dispute does not necessarily mean "game over" for the PCR that comes runner up.


1. Julie Hunter v, Inc. and others [2024] CAT 8.

2. Evans v. Barclays Bank plc and Michael O'Higgins FX Class Representative Limited v Barclays Bank plc [2022] CAT 16.

3. See alsoClaudio Pollack v Alphabet Inc. and others [2023] CAT 34; Charles Arthur v Alphabet Inc. & Others [2023] CAT 34 where the CAT ordered for the issue of carriage to be determined as a preliminary issue, however the proposed class representatives subsequently consolidated their applications before the carriage hearing took place.

4. Evans v Barclays Bank Plc & Ors (Rev1) [2023] EWCA Civ 876. See paragraphs 139, 146, 147, 148 and 153.

5. A test derived from the judgment of the Canadian Supreme Court in Pro-Sys Consultants v Microsoft Corporation [2013]SCC 57.

6. Paragraphs 27 – 36 of the Ruling set out the reasons for the CAT's decision.

7. See: MOL v McLaren [2022] EWCA Civ 1701; Merchant Interchange Fee Umbrella [2023] CAT 60;Kent v Apple Inc [2023] CAT 22; and PSA Automobiles SA v Autoliv AB [2023] CAT 66.

8. See Dr Liza Lovdahl Gormsen v Meta Platforms, Inc. and Others [2023]CAT 10 and Commercial and Interregional Card Claims I Limited v Mastercard Incorporated & Others and vs Visa Inc. & Others [2023] CAT 38.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

See More Popular Content From

Mondaq uses cookies on this website. By using our website you agree to our use of cookies as set out in our Privacy Policy.

Learn More