Well-equipped to handle the full gamut of complex disputes, Byrne Wallace Shields LLP is praised for its ‘honesty, directness, diligence and responsiveness’ and is noted for its role in government instructions relating to infrastructure and tech projects, AI and international issues, including trade, tariffs and sanctions. Leading the group is Jon Legorburu, who has a strong regional reputation for public sector disputes, as well as for handling regulatory, corporate and white-collar crime mandates. Mona Costelloe is a seasoned litigator who focuses on property, public law, regulatory enforcement and commercial disputes. Jill Callanan has deep experience before the High Court in a range of commercial litigation matters, notably contractual, shareholder, property and competition disputes, while Ian Lavelle is a key contact for domestic and international businesses in commercial disputes, and Clare Dowling is skilled in property and corporate litigation. Eoin Mac Aodha joined the group from Eversheds Sutherland in September 2025.
Legal 500 Editorial commentary
Testimonials
Collated independently by Legal 500 research team.
- ‘We would highly rate the team we work closely with - Helen Gibbons: calmness, clarity and guidance; Jon Legorburu: guidance and oversight.’
- 'There is one partner I specifically work with on fitness to practice matters, Eoin McGlinchey, who I would like to mention. Eoin's depth of knowledge and understanding of the law governing professional practice issues is extensive. His capacity to match this knowledge and understanding to the specific needs of both our organisation and our individual members is exceptional. Eoin is a professional we know we can rely on!’
- ‘Peter Hennessy has been a great support during our engagement with BW. Always able to get in touch if we have queries and will endeavour to respond to any issues quickly. We built a good, trustful working relationship with Peter and the team as we worked through our dispute resolution.’
- ‘Eoin Mac Aodha is as high quality and very measured and thoughtful litigator.’
- ‘Honesty, directness, diligence and responsiveness.’
- ‘Byrne Wallace Shields LLP are an excellent firm with dedicated partners and professionals. They are incredibly approachable and provide excellent customer service. I would and have highly recommended them to colleagues and family.'
Key clients
- Fidelis
- National Treatment Purchase Fund Board
- Cabot Financial (Ireland) Limited
- Residential Tenancies Board
- Coface US and Coface UK
- Ballymore Group/Ballymore Residential Limited
- O’Malley Ireland Spirits Trading Limited and Nonto DAC
- Health Service Executiv
- JSC Properties Ltd
- An Coimisiún Pleanála (formerly An Bord Pleanála)
- Aviva Insurance Ireland DAC
- Advent Insurance DAC
Work highlights
Acting for Fidelis in the multi-billion dollar Russian aircraft insurance litigation.
Advised Cabot Financial on strategic, legal and operational issues arising from a cyberattack on its computer systems.
Acting for An Coimisiún Pleanála (the Planning Authority) in Coolglass Windfarm v An Bord Pleanála, which is the subject of a leap frog appeal to the Supreme Court. The case concerns issues of climate law and how public bodies such as the Planning Authority ought to consider climate matters.
Lawyers
Next Generation Partners
Junior partners with significant recognition from clients and peers in the market and key roles on multiple matters.
Practice head
Jon Legorburu
Other key lawyers
Mona Costelloe; Jill Callanan; Ian Lavelle; Clare Dowling; Shane Neville; Eoin Mac Aodha; Peter Hennessy; Helen Gibbons