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Karen Denny
Partner

Karen Denny

London, United Kingdom
Languages
  • English
Social media

Karen covers all areas of corporate disputes, particularly those with an international law and cross border emphasis. Her experience includes advising on matters of sovereign immunity, freezing injunctions, the enforcement of foreign judgments, and obtaining evidence for use in overseas proceedings, complex fraud and contractual disputes, defamation, confidentiality and privacy disputes.

Karen has represented various sovereign states and their governmental agencies, international organisations and other entities in relation to public international law matters in particular regarding their unique immunities and privileges.  She leads the public international law practice group and has been ranked as a Leading Individual by Legal 500 in Public International Law since 2018.

Awards & Recognitions
01 –
  • Quote
    "It is rare for a law firm to understand so well the issues that are specific to multilateral development banks, which straddle both the private sector and public sector worlds. In this regard, Karen Denny, and the CMS team by association, stand out."
    Legal 500, 2025
  • Quote
    "Clients highlight Karen Denny for her deep understanding of matters related to public international law."
    Legal 500, 2025
  • Quote
    "an outstanding lawyer."
    Legal 500, 2023
  • Quote
    "Karen Denny is outstanding. She has a breadth of knowledge in this area which is impressive. She is also excellent with clients."
    Legal 500, 2021
  • Quote
    "Karen Denny is a class act. She always puts the client first, and has a deep interest in and knowledge of the public international law field."
    Legal 500, 2021

Relevant experience

  • United States of America – acting on its behalf in its successful assertion of state immunity in the House of Lords, Holland v Lampen-Wolfe [2000] 1 WLR1573.
  • US Secretary of State for Health – acting on his behalf in obtaining one of the first orders of its kind for disclosure by a third party under CPR5.4C(2) for the provision of various medical reports from the UK MMR litigation for use in the US MMR autism group litigation, Sayers & Ors v Smithkline Beecham Plc & Ors [2007] EWHC 1346(QB).
  • Costco Wholesale – acting on its behalf in respect of the construction of certain NHS Ophthalmic Regulations in the matter of Costco Wholesale UK Ltd v Milton Keynes Primary Care Trust [2008] ALL ER (D) 265.
  • SEC – acting on its behalf in its successful application for the continuance of a freezing injunction unanimously upheld by the Court of Appeal, in what is believed to be the first decision of its kind in granting the order to a foreign claimant without the requirement for a cross undertaking, United States Securities and Exchange Commission v Manterfield [2008] ALL ER (D) 218.
  • SEC – acting on its behalf in the successful grant of a freezing injunction in relation to Sir Allen Stanford, and various Stanford companies’ assets in the UK United States Securities and Exchange Commission v Stanford International Bank Limited and Others [2009].
  • Acting on behalf of the Liquidators of KSF (IOM) Limited in Kaupthing Singer and Friedlander Ltd [2009] EWHC 740 (Ch).
  • Acting on behalf of the Liquidators of KSF (IOM) Limited in Brazzill & Ors v Willoughby & Ors Court of Appeal [2010] EWCA Civ 561
  • United States of America – acting on its behalf in relation to whether it is bound to consult with its local civilian employees about redundancies before taking the decision to close a military base as a result of strategic policy re-alignment decisions, and how domestic statutes should be interpreted to give effect to customary international law, United States of America v Nolan [2015] Supreme Court.

Lectures list

  • Presentation / seminar at the UK Supreme Court in December 2015

Education

  • 1986 – Law LLB (Hons) –First Class – Leicester University
  • 1987 – Law Society Finals – First Class – Chester Law School
  • 1987 – City of London Solicitors Company Alfred Syrett Award
Practice Areas
Dispute Resolution Commercial Disputes Corporate Crime, Compliance and Forensics

Insights by Karen

See all Insights
Legal Update United Kingdom

Supreme Court confirms the scope of state immunity in relation to the registration of ICSID arbitration awards

16 Mar 2026 9 min read
Event United Kingdom

CMS Disputes 101 Annual Webinar Series – Now Available On-Demand

02 Sep 2025
Legal Update United Kingdom

High Court clarifies approach to Letters of Request

26 Aug 2025 10 min read
Legal Update United Kingdom

The UK Court of Appeal determines that the Kingdom of Bahrain does not have immunity in a spyware case

14 Oct 2024 11 min read
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