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Philip Mansfield

Partner Global Co-Head Antitrust


Mansfield Philip
Philip Mansfield

Partner Global Co-Head Antitrust


Philip Mansfield is a senior partner based in London and co-head of Allen & Overy's global antitrust group. He has led meetings with agencies around the world on merger, cartel and behavioural matters for various clients, including with the European Commission, UK agencies, U.S. Department of Justice, U.S. Federal Trade Commission, U.S. Court of North California, South Korea's Fair Trade Commission, the Japan Fair Trade Commission and China's Ministry of Commerce.

Philip regularly obtains approval for complex mergers and joint venture arrangements, particularly in the high-tech sector and was twice a winner of the Global Competition Review Matter of the Year. His experience includes advising Maersk Drilling on its merger with Noble Corporation; Maersk on its acquisition of LF Logistics; NortonLifeLock on its acquisition of Avast; Refinitiv (and shareholder Blackstone) on the EC review and worldwide filings of Refinitiv's proposed USD27bn acquisition by the London Stock Exchange Group; Symantec Corporation on the US$10.7 billion sale of its Enterprise business to Broadcom; Hitachi on its JV with Honda in the automotive sector; HP on its acquisition of Apogee; Cisco on the sale of its NDS business; GitHub on its sale to Microsoft and Seagate on its acquisition of Samsung HDD and Xyratex.

Philip has extensive cartel experience and is a regular speaker at the signature IBA/ABA cartel conference. In 2016 Philip won Global Competition Review Behavioural Matter of the Year for the firm’s role on the European Commission’s credit defaults swap investigation. Matters include advising a party in the first EU settlement case (DRAM); as well as advising parties in each of the FX, Rubber Chemicals, EPDM, Heat Stabilisers, GIS, Power Transformer, LCD, CRT and Auto Parts investigations. More recently Philip has developed extensive experience in advising financial institutions on a number of cartel investigations and Financial Conduct Authority market studies, including strategies surrounding the merits of making immunity/leniency applications to the UK Competition and Markets Authority and the EC and engaging in settlement discussions with the EC. Philip recently successfully guided Newton Investment Management Limited (part of BNYM) through the Financial Conduct Authority’s first ever investigation brought using its competition enforcement powers. He is currently advising clients on their defences to several separate follow-on damages actions before the English and German courts and has represented claimants in the English courts.

Philip has an established track record of representing companies in successfully raising and defending behavioural complaints before the EC and the English courts relating to interoperability (Sun Microsystems/Microsoft, PSI/IBM), bundling (Microsoft/Opera, Microsoft/Vista), patent pools (Premaitha, DVD6C/iODRA) and patent ambush (Micron/Rambus).

“Philip is an absolutely outstanding adviser.” - Chambers UK 2023, Competition Law

“He is a strong business partner who is pragmatic with strong expertise.” - Chambers UK 2023, Competition Law

“Philip Mansfield is a true legal/business partner who takes the time to understand the company and business.” - Legal 500 UK 2022, EU and Competition

“He has great client relationships and is super knowledgeable when it comes to antitrust investigations.” - Chambers UK 2022, Competition Law

Experience highlights

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Admitted as solicitor (England and Wales), 1995

Admitted as solicitor (Ireland), 2018


MA, Downing College, Cambridge University

Other noteworthy experience 


  • Maersk on the competition aspects of establishing Tradelens, its JV with IBM to digitise its global supply chain.
  • Fox Networks Group on the investigation by the EC into alleged anti-competitive behaviour surrounding the acquisition of EU sports rights.
  • Hitachi on a number of large M&A transactions, including the acquisition of JR Automation and Chassis Brakes International, and the global auto-parts joint venture with Honda.
  • Hitachi in relation to the European Commission’s Auto Parts investigation, where Philip succeeded in having Hitachi dropped from multiple elements of this case. He has also worked with Hitachi on various global cartel matters, including the LCD, CRT, GIS and Power Transformers investigations, and associated damages claims before the English Courts.
  • Seagate on the EU and worldwide merger control aspects of its USD1.4bn acquisition of the hard disk drive business of Samsung Electronics and on its acquisition of Xyratex.
  • Sun Microsystems on the EU merger control aspects of its USD7bn merger with Oracle. This was a high-profile and controversial EU merger investigation which ended in an unconditional clearance decision in the face of significant vocal opposition.
  • A global financial institution on the multi-jurisdictional investigation by a number of regulators and prosecutors into the manipulation of the foreign exchange (Forex) market, and resulting antitrust damages claims.
  • Micron on the acquisition of a joint controlling interest in Inotera and various other acquisitions.
  • GitHub in relation to its USD7.5bn acquisition by Microsoft.
  • Cisco on the sale of its NDS business, and on the global merger control aspects of its GBP543m recommended cash offer for IMImobile.
  • A multinational information technology company on its GBP380m acquisition of managed print services business Apogee from private equity fund Equistone and management sellers.
  • Peloton on the merger control aspects of its landmark acquisition of Precor.
  • Symantec Corporation on the USD10.7bn sale of its Enterprise business to Broadcom.

Pro bono 

He is a trustee of Allen & Overy’s London Foundation and a Governor of the Raines Foundation School.



Top 3, Global Elite firms

Global Competition Review, 2020

Competition Team of the Year

British Legal Awards, 2018

Competition Team of the Year

Legal Business Awards 2017