Christopher Monaghan, instructed by Geradin Partners and led by Kieron Beal KC of Blackstone Chambers, acted for Prof Andreas Stephan in successfully resisting Amazon’s application to remove its largest sellers from his opt-out class action. The Competition Appeal Tribunal (Sir Peter Roth (Chair), Charles Bankes and Keith Derbyshire) announced at the end of the hearing on 8 September 2026 that the application would be refused. It gave its unanimous reasons on 10 November 2026: [2026] CAT 84. Daniel Carall-Green and Hannah Bernstein are also acting for the class representative.

Prof Stephan brings collective proceedings on behalf of merchants who sold on Amazon’s UK marketplace, alleging that Amazon abused its dominant position. The case, estimated at over £2.6 billion, was certified on an opt-out basis in July 2025, and the Court of Appeal refused Amazon permission to appeal in February 2026.

Following the Supreme Court’s decision in Evans v Barclays Bank plc [2025] UKSC 48, Amazon applied in May 2026 to vary the collective proceedings order. It sought to exclude from the opt-out class the roughly 1,000 merchants whose sales on Amazon exceeded £10 million over the claim period, so that they could join the case only by opting in.

The Tribunal was “clearly satisfied” that the application should be refused. Its reasons included:

· Evans does not mean that proceedings should be opt-in whenever larger class members could practicably opt in. The Tribunal rejected Amazon’s “rather mechanistic approach”: almost every business class includes some large companies, and the regime does not operate “in such a straitjacket”.

· Sales of £10 million over six years do not make it practicable for a merchant to opt in. Many of the 1,000 merchants could not reasonably make an informed decision to join a complex case “against one of the largest corporations in the world”.

· The £10 million cut-off was “entirely arbitrary”. Even on Amazon’s cut-off, about 60% of the value of the case would stay in the opt-out class: its core value lies in “the mass of more modest claims”.

· Book-building, funding, certification and an opt-in period would take “well over a year”, and granting the application would “almost inevitably” have postponed the first trial. There was “no satisfactory explanation” for Amazon waiting until May 2026 to apply.

· Further delay would be “very unfair” to the consumer class in the related Hammond proceedings, which are being heard together with Prof Stephan’s case.

The judgment follows the Tribunal’s refusal of similar applications made after Evans by Google in Rodger (discussed here) and by Apple in Ennis (discussed here), and its rejection of Google’s argument for opt-in certification in Brook (discussed here). The first trial in Prof Stephan’s case, on market definition, dominance and abuse, is fixed to start on 25 April 2028.

The judgment can be found here.