Sarina Williams

Litigation, Arbitration & Investigations Partner, London

"I advise corporates and financial institutions on their defence of complex, high-value, often funded, competition litigation and class actions before the English courts and Competition Appeal Tribunal. I also advise on the conduct of competition regulatory investigations and enforcement, and associated litigation risk. I aim to provide clear and commercial advice to help clients develop strategies to defend and resolve complex competition disputes."


Professional experience

Education and qualifications


Sarina is a Partner in the Litigation, Arbitration & Investigations team in London and Co-Head of the firm’s Competition Litigation practice. She has a wealth of experience advising corporates and financial institutions on contentious and regulatory matters, particularly in relation to competition litigation and competition regulatory issues. She is ranked as a “Next Generation Partner” for competition litigation by The Legal 500.

Sarina has extensive experience in the conduct of complex, high-value, often funded competition litigation before the High Court of England and Wales, the Competition Appeal Tribunal, the Court of Appeal and the Supreme Court. She is currently acting for defendants in high-value proceedings relating to alleged antitrust infringements concerning interchange fees, ATM transactions, foreign exchange, car parts, emissions, power cables, certain pharmaceutical products and a tech company’s digital store.

Sarina has significant trial experience for competition damages claims, having conducted (amongst other things) a three and a half month first instance trial, a ten-day Court of Appeal hearing and a four-day Supreme Court hearing in the first wave of the interchange claims. She has also been involved in key cases establishing competition law in the UK, including the interchange cases (which are a leading authority on limitation, restriction and pass-on) and the pharmaceutical cases (which are leading authorities on excessive pricing). Sarina works in close collaboration with lawyers from the firm’s other market-leading practice areas, including Antitrust and Foreign Investment, Financial Regulation and Corporate in cross-office, multidisciplinary teams.

Sarina is passionate about social mobility, gender equality, and ending the stigma around mental health awareness.

Work highlights

Sarina’s recent matters include:

  • acting for a significant mobile phone operator in its defence of a competition collective action relating to alleged overcharging of customers following the end of their minimum contractual term;
  • acting for a leading payment scheme in relation to numerous “stand alone” litigation proceedings brought by major retailers alleging that multilateral interchange fees on card transactions were levied in breach of Article 101 and Article 102 TFEU (and various domestic competition laws) across the High Court and the Competition Appeal Tribunal;
  • advising a leading payment scheme on two collective actions (one opt-in and one opt-out) brought by retailers in respect of interchange fees before the Competition Appeal Tribunal;
  • advising a global financial institution on its defence of large group litigation relating to alleged competition law breaches concerning FX trading;
  • advising a global technology company on its defence of a class action alleging abuse of dominance relating to operation of its digital store;
  • acting for a defendant regarding Part 20 contribution proceedings brought in the UK in relation to damages actions following from the power cables cartel;
  • advising a large payment scheme on its defence of proceedings brought by an independent ATM operator which alleges that Visa’s rules relating to ATM transactions breach various European and domestic competition laws;
  • advising a large car manufacturer on multiple sets of group litigation arising from the European Commission’s AdBlue decision;
  • advising a large car parts manufacturer on threatened competition damages actions in the English court in relation to the car parts cartels; and
  • advising companies in the pharmaceuticals sector on CMA investigations and subsequent appeals to the Competition Appeal Tribunal, and associated litigation risk.

Professional experience

Sarina is a regular panellist and author on competition litigation and class actions in the UK.

In particular, Sarina is co-editor of The Legal 500’s 2022 comparative guide on competition litigation, was a panellist at the first UK Collective Actions Symposium and is regularly quoted in the press with her views on competition litigation and class actions (for recent examples, see The Times, the FT, Law360, Legal 500 IHL magazine and GCR).

Sarina is also Chair of the ICC Global Competition Commission’s task force on antitrust damages claims.

Education and qualifications

Sarina studied Law at Downing College, University of Cambridge.