Mark Deem


I am passionate about working with my clients to protect their assets and supporting them through critical times in their commercial lives.

+44 (0) 20 7556 4425

Mark Deem is a commercial litigator, with considerable experience of complex domestic and cross-border litigation, international arbitration and regulatory matters. He has conducted litigation in all commercial divisions of the English High Court, Court of Appeal, Supreme Court and Court of Justice of the EU; represented clients in international arbitration proceedings under the rules of the ICC, LCIA, RIDR and IFTA; and has a broad experience of mediation and other dispute resolution mechanisms.

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  • Several financial institutions and FTSE-100 companies in relation to data breach issues 

  • A leading global technology company in a multi-million pound dispute 

  • $220 million contractual dispute concerning credit derivative swap and cross-border leasing transactions  

  • FTSE-100 company on a £600 million contractual dispute 

  • Mobile network operator on a £100 million contractual dispute concerning a telecommunications joint venture 

Not only unerringly astute, but always commercially on point. He exhibits a real world sensibility that’s rarely found in lawyers. – James Rock, CEO, The Rock Group

  • College of Law, Guildford
    LPC, 1998

  • Downing College, Cambridge
    MA, 1997

Admissions & Credentials

England & Wales

Rankings & Accolades

    FT Innovative Lawyers Europe: Technology and Data Analytics (2016)

    FT Innovative Lawyers: Dispute Resolution (2015)

    Legal 500 UK: Dispute Resolution and Data Protection and Privacy


+44 (0) 20 7556 4425 office

69 Old Broad Street
London, UK EC2M 1QS