“Mark Sansom is one of the UK’s leading competition litigators and a recognised authority on collective actions, antitrust damages claims, and the evolving landscape of private enforcement. As UK and Ireland Managing Partner of Freshfields, Mark combines his leadership role with a full litigation practice, bringing strategic insight and deep sector expertise to some of the most significant competition disputes in the UK and Europe.

Mark has been at the forefront of many of the landmark cases shaping the UK competition litigation regime in the Competition Appeal Tribunal (CAT), High Court and appeal courts. He is widely known for his work on high‑profile opt‑out collective proceedings and for his extensive experience navigating complex, often multi‑jurisdictional antitrust issues. His practice also spans UK and EU investigations, market studies, and competition‑related arbitrations, in which he has appeared as an advocate before arbitral tribunals.

Mark is ranked as a top practitioner in all the major legal directories. He is listed by Chambers as a Global Elite Thought Leader in both Competition Litigation and Law Firm Management, was included in The Lawyer’s Hot 100 in 2024, and has twice been voted Global Competition Review’s worldwide Litigator of the Year (2019 and 2025).

He regularly speaks on developments in competition litigation, collective proceedings, and the strategic challenges facing businesses, boards, and legal teams in an increasingly complex enforcement environment.”