Partner - Head of Group Actions and Competition, London
Genevieve advises corporate and individual clients in a broad range of commercial disputes in the banking and finance, private equity, luxury, hospitality and leisure, retail, media and telecoms sectors. She leads the firm's Group Actions and Competition team.
Language - English
Jurisdiction - England & Wales
Genevieve Quierin is a partner at Stephenson Harwood, where she represents a diverse range of corporate and individual clients across sectors such as banking, finance, private equity, luxury and media. Her practice is broad, covering everything from strategic pre-action advice to high-stakes multi-jurisdictional litigation. Clients appreciate her ability to distil complex issues into clear, actionable strategies, making her a sought-after advisor in both claimant and defendant roles.
Genevieve's expertise extends to competition private enforcement actions, many of which are group actions. She is known for her pragmatic approach, working closely with third-party litigation funders and insurers to ensure her clients' interests are robustly protected.
Clients value Genevieve's commitment to high standards of service and her ability to think commercially, setting her apart in the legal landscape.
Genevieve was recently named in The Lawyer Hot 100 2025 and featured in Global Competition Review’s - Women in Antitrust. She is ranked as a Leading individual in Legal 500 for Dispute Resolution, specifically in Banking Litigation: Investment and Retail, Commercial Litigation: Premium, and Group Litigation: Claimants. Additionally, Chambers UK ranks Genevieve for her expertise in Competition Law: Private Enforcement: Claimant, as well as Commercial and Corporate Litigation.
Merchant Interchange Umbrella Proceedings
Represented almost 2,000 corporate claimants in group claims against Visa and Mastercard seeking recovery of losses caused by unlawful Multilateral Interchange Fees set by Visa and Mastercard on every card transaction processed by the clients in the UK and Europe. A trial on liability issues took place over 6 weeks in early 2024, with a judgment finding for the Stephenson Harwood claimants on all issues handed down in June 2025 and a trial on pass-on issues took place over 7 weeks between November 2024 and April 2025. The claims were successfully settled with Mastercard in June 2024 and with Visa in April 2025.
Alleged cartel claim
Acting for 7 of the UK's largest supermarket groups (Aldi, Asda, Co-op, Iceland, Marks and Spencer, Morrisons and Ocado) in claims arising from an alleged cartel in the market for farmed Atlantic salmon. The alleged cartel is under investigation by the European Commission, which has issued a Statement of Objections. The claim is estimated to be worth hundreds of millions of pounds. Our clients successfully defended a jurisdiction challenge brought by 6 separate defendant legal teams in March 2025.
Unfair Prejudice Petition
Acted for Saxon Woods and successfully secured a finding of unfair prejudice against the Chairman of the board of directors following a heavily contested five-week liability trial in the Business and Property Courts in late 2023. Successful on appeal to Court of Appeal in February 2025, with the appellate court finding the party responsible for the unfairly prejudicial conduct to be dishonest and to have breached his duties under s.172 Companies Act.
Advising Investor in relation to Funding and Law Firm dispute
Advising the investor in a law firm in relation to issues arising from the demise of the firm and retraction of funding including breaches of fiduciary duty, breach of contract and allegations of champerty.
Collective proceedings against Amazon
Representing the Association of Consumer Support Organisations (ACSO) in collective proceedings against Amazon on behalf of more than 45 million UK consumers. ACSO’s proposed collective proceedings relate to Amazon’s price parity policies and allege that Amazon's price parity policies protect it from healthy price competition from rival e-commerce marketplaces and lead to higher prices for UK consumers.
Advising Steering Committee in Fraud Action
Advising the steering committee of a large group fraud action in relation to confidential matters arising from difficulties encountered in the underlying group action, including the withdrawal of funding and potential exposure to adverse costs.
Marks and Spencer PLC v Mastercard Incorporated and Others
Acting for M&S in connection with its claim for damages against Mastercard in relation to multilateral interchange fees.
Payment sector disputes
Representing five of the largest betting and gaming companies in payments sector disputes.
