Owen O'Sullivan

Managing Partner

+353 1 639 5368
owen.osullivan@williamfry.com vCard Linkedin

Owen O'Sullivan is the Managing Partner of William Fry and former Head of our Litigation & Dispute Resolution Department.  He specialises in commercial disputes, particularly shareholder and investment disputes, as well as disputes in the financial sector. He has been involved in many high profile property disputes and has product liability defence experience in the pharmaceutical, energy drink, motor and tobacco sectors.

Recent significant work includes advising:

  • Horizon Sports Management on the defence of  the claim brought against it by golfer Rory McIlroy and the prosecution of its counterclaim.
  • Alternative Advantage plc in Commercial Court proceedings for the return of over €100m sub-custodied to Bernard Madoff
  • Tesco on its contractual dispute relating to the development of a new district centre store at Carrickmines.
  • Davy Stockbrokers both on its successful Supreme Court challenge to a decision by the Financial Services Ombudsman and ongoing defence of Credit Union litigation
  • DCC plc through its High and Supreme Court insider dealing action brought by Fyffes plc and the subsequent Inspectorship process

Owen served as a member of the Law Society’s Litigation Committee for six years and is currently a member of the International Bar Association, the Steering Committee of the Commercial Litigation Association of Ireland and DRI Europe.

Sources note his presence in "market-leading commercial litigation" and praise his ability to lead complex claims. Chambers Global 2021 

Owen garners widespread praise for his expertise in shareholder disputes and regulatory enforcement actions. "He is surgical in his approach; he can pick a case apart to find the strengths and weaknesses," says one impressed interviewee. Chambers Europe 2020

Another source notes: "He understands all of the issues involved in going to court and is good at explaining those issues." Chambers Europe 2020

Owen has been ranked has a 'Leading Individual' in Legal 500 2020, where one client mentioned he is a "great tactical thinker."

Owen is a leading figure across complex commercial disputes and judicial reviews. Sources describe him as "an excellent litigator" and a "very polished operator." Chambers Europe 2019

Market commentators describe Owen as "deadly efficient, thorough, cool and analytical" in his approach to commercial litigation. Chambers Global 2018

Owen O’Sullivan is "an excellent legal thinker". Legal 500 EMEA 2018

Owen is recognised in Best Lawyers 2019 under 'The Best Lawyers in Ireland' for work in Arbitration & Mediation, Bet-the-Company Litigation, Litigation and Product Liability Litigation 

In Chambers Global 2017 Owen receives plaudits from a range of market commentators, describing him as an "excellent corporate litigator" and "a very astute operator" who has "very tactical and good commercial judgement" and  "very well regarded and a good litigator." 



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