Philip Mansfield


Philip 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; a multinational information technology company 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 the subsidiary of a global financial institution 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).


Representative matters

Hitachi in relation to the European Commission’s Auto Parts investigation. Philip succeeded in having Hitachi dropped from multiple elements of this case.
Refinitiv (and shareholder Blackstone) on the EC review and worldwide filings of Refinitiv's proposed USD27bn acquisition by the London Stock Exchange Group.
A global investment management firm in relation to the first investigation opened by the UK Financial Conduct Authority using its competition enforcement powers.
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 European Commission into alleged anticompetitive behaviour surrounding the acquisition of EU sports rights.
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.
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 on its sale to Microsoft.
Cisco on the sale of its NDS business.
A multinational information technology company on its GBP380m acquisition of managed print services business Apogee from private equity fund Equistone and management sellers.

Pro bono

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

Speaking Engagements

  • Guest speaker, LMA and LSTA Conference, 2019
Philip Mansfield has an amazing ability to go to the core of the competitive query, brainstorm and intuitively advise on the spot in a way that rationalizes and clarifies the inhouse legal thinking and analysis.
Legal 500 2024 - EU and Competition
We chose to work with Phil Mansfield because of his excellent work in this area, his knowledge of our industry and business, and his practical and efficient style with complex and difficult work.
Chambers UK 2024, Competition Law


  • 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
  • Global Competition Review Behavioural Matter of the Year for the firm’s role on the European Commission’s credit defaults swap investigation, 2016



Admitted as solicitor (England and Wales), 1995

Admitted as solicitor (Ireland) 2018


MA, Downing College, Cambridge University


A&O Shearman was formed on May 1, 2024 by the combination of Shearman & Sterling LLP and Allen & Overy LLP and their respective affiliates (the legacy firms). Any matters referred to above may include matters undertaken by one or more of the legacy firms rather than A&O Shearman.