Rosaleen Byrne

Experience

Rosaleen has over 25 years’ experience handling complex and large-scale disputes across a range of sectors, specifically financial services, communications, digital services, aviation, pharmaceutical, and pensions. Ranked ‘Band 1’ by Chambers & Partners and ‘Leading Partner’ by Legal 500 for Dispute Resolution, Rosaleen is one of Ireland’s ‘go to lawyers’ for advising stakeholders on complex high value disputes in regulated sectors. Her commercial disputes practice focuses on cases with regulatory and economic dimensions and encompasses investigations, statutory inquiries and enforcement actions. Rosaleen is also regularly engaged on competition / anti-trust cases including state aid litigation and follow on damages actions and has worked on pan-European teams with Europe’s leading competition lawyers and economists. Rosaleen also has considerable experience of representative actions and test cases.

Rosaleen is highly regarded for her investigations practice which spans statutory investigations /inquiries / adjudications and corporate investigations. Rosaleen’s work includes advising on all aspects of investigations from dawn raids and crisis management to inquiry hearings, assessment of harm calculation of financial penalties and findings and regularly involves advising on the complex interplay between white collar crime and regulatory breaches. 

Key highlights include advising:

• IBRC (in Special Liquidation) in a long running High Court action against the former CEO of Irish Nationwide Building Society including a 3 month trial (2025) and the successful defence of an application to stay the trial, which application was ultimately determined by the Supreme Court.
• Central Bank of Ireland in respect of several high-profile High Court actions, appeals, statutory applications and investigations.
• Commission for Communications Regulation (ComReg) in several cases concerning wholesale telecoms regulatory decisions or enforcement actions. Most recently (2024) in a Commercial Court case successfully defending a challenge to a dawn raid and establishing a protocol for the management of data collected by regulators.
• In follow-on damages claims for breach of competition law brought in the Irish courts following a finding of infringement by the European Commission.
• Representing a defendant in one of Ireland’s longest running cases for damages for alleged cartel conduct in the cement sector.
• Representing a European Member State in an action brought in the Irish Courts to recover state aid which had been granted by the Member State to an Irish corporate and had subsequently been determined by the Commission to have been unlawful.
• Aircraft lessors on complex and contentious repossession disputes.