Mr Mark O’Shaughnessy > ByrneWallace LLP > Dublin, Ireland > Lawyer Profile

ByrneWallace LLP
88 Harcourt Street
Saint Kevin's
DO2 DK18

Work Department

Litigation and Dispute Resolution


Partner, Litigation and Dispute Resolution


Mark is a litigation and regulatory investigations partner in ByrneWallace LLP.

Mark advises domestic and international organisations on complex disputes with a particular focus on corporate disputes, contentious intellectual property and insurance matters in the education, health, life science and TMT sectors.

He also has extensive experience in advising private, semi-state and public organisations in the context of regulatory investigations and enquiries.

Reputation management is core to Mark’s expertise and he has managed the corporate reputation strategies of numerous companies through times of crisis.


  • Law Society of Ireland
  • Law Society of England and Wales
  • Dublin Solicitors Bar Association
  • Arbitration Ireland
  • British Irish Commercial Bar Association


  • Law and Accounting, University of Limerick, 2003
  • Admitted as a Solicitor, Law Society of Ireland, 2008
  • Diploma in Commercial Litigation, Law Society of Ireland, 2009
  • Professional Diploma in Arbitration, University College Dublin, 2011

Lawyer Rankings

Ireland > Media and entertainment

ByrneWallace LLP stands out for its focus on advising organisations on reputation management, including assisting clients with seeking to have defamatory material removed from social media. The practice also advises organisations on incidents in which others impersonate the organisation through the unauthorised use of trade marks. Mark O’Shaughnessy leads the team and is supported by the firm’s litigation practice in contentious cases.

Ireland > Intellectual property

ByrneWallace LLP is regularly instructed by clients in intellectual property litigation, including passing-off and trade mark infringement claims. The practice also specialises in advising companies in the pharmaceutical sector on IP matters, such as licensing and research and collaboration agreements. Colin Sainsbury leads in this area and also heads the firm’s life sciences practice. Darren Daly advises on IP issues in other sectors including hospitality, retail and education, while Mark O’Shaughnessy handles contentious matters.

Ireland > Insurance

ByrneWallace LLP‘s broad capabilities are deployed across the spectrum of transactional, regulatory and contentious matters. It has a fine reputation in the healthcare and environmental segments, and has experienced a steady increase in dispute-related engagements. Jon Legorburu heads the litigation and dispute resolution team and leads the insurance group and litigation partner Mark O’Shaughnessy has a strong background in the insurance sector, including in the environmental sphere.

Ireland > Dispute resolution

ByrneWallace LLP remains best known for contentious matters involving public sector bodies, including those in the health, education and tourism sectors. Jon Legorburu leads the team and has an impressive history in commercial litigation and public sector disputes. Mona Costelloe is another senior name with extensive expertise in real estate disputes, regulatory enforcement matters and more general commercial litigation. Sean O’Donnell is also noted for contentious regulatory work, and Mark O’Shaughnessy is a growing force in the market. Valerie Hourigan is rated for real estate and procurement disputes.