Claire Jeffs > Slaughter and May > London, England > Lawyer Profile

Slaughter and May

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Work Department




Claire is Co-Chair of the Competition Group globally and works in Slaughter and May’s Brussels and London offices.

Claire has extensive experience of both EU and UK competition law. She has been involved in a large number of high-profile merger cases before the EU and UK competition authorities, as well as coordinating merger approvals worldwide. On the contentious side, she has been involved in many cartel and other behavioural cases, including on appeal to the General Court in Luxembourg.


Joined firm  in 1998. Partner since 2005.


French and Russan (fluent). German (proficient).


University of Cambridge, University of Brussels

Lawyer Rankings

London > Corporate and commercial > EU and competition

(Hall of Fame)

Claire JeffsSlaughter and May

Slaughter and May‘s competition practice is truly market-leading, frequently assisting with the most complex and significant deals and investigations in the market. The group has a demonstrable track record of achieving outstanding results for clients before regulatory bodies; as a recent example, Bertrand Louveaux advised Deliveroo on a CMA phase II investigation into Amazon acquiring a minority interest in the company, which resulted in a rare unconditional Phase 2 clearance. The team is able to call on a number of respected partners, including Claire Jeffs (co-lead of the department alongside Louveaux) and Isabel Taylor, who is a ‘ shrewd, practical and knowledgeable expert in subsidy control/State aid’. Philippe Chappatte is another well-known name and assists with market investigations. Jackie Holland joined Cleary Gottlieb Steen & Hamilton in early 2021.

Belgium > Competition: EU and global

Slaughter and May combines an active merger control practice, including high-profile involvement in major global clearances, with a strong record in major antitrust investigations and litigation, notably the Google AdSense case, state aid matters, marketing and consumer issues, and follow-on damages proceedings. The practice is active on behalf of major multinational names, and draws upon expertise from Brussels resident partners as well as London-based members of the Brussels Bar. Key names in the team include Bertrand Louveaux and Claire Jeffs, co-chairs of the competition team, Brussels office head Anna Lyle-Smythe, and Natalie Yeung, who takes the lead on Asia-domiciled matters. Jordan Ellison and Kerry O’Connell are also noted for their strong work on mergers and broad antitrust issues.