Pat Treacy


Pat has specialised in EU law and competition law since the 1980s, handling landmark cases at EU and national level and helping clients from all over the world with their competition law needs. She has particular strengths in advising on the complex legal and policy issues arising where competition law and intellectual property law intersect having been a leader in this field as it has increased in importance over the last quarter of a century or more. Consequently, many of her clients are in high technology sectors including life sciences and tech.

Pat represents clients before the competition authorities and the courts, and advises on complex agreements (including settlement, R&D, licensing and joint venture agreements). She advises regularly on the competition law responsibilities affecting dominant companies – particularly where access to, or the exercise of, IP is concerned. She and her team assist clients with competition compliance and preparation for “dawn raids”, supporting clients through such dawn raids and their aftermath.

Pat was appointed Deputy High Court Judge in September 2018, and will serve in the Chancery Division of the High Court of England and Wales for four years. The part time nature of this appointment enables Pat to continue as a Partner, leading the team and working with clients.

Pat is a member of the Competition Law Association; the UK Association of European Lawyers; and the Competition Section of the Law Society.  She is on the editorial board of both the Journal of Intellectual Property Law and Practice and Competition Law Insight. Pat lectures and writes widely on topical issues. She also teaches the competition law module on the University of Oxford Postgraduate Diploma in Intellectual Property Law and Practice course.


  • MA Law, University of Cambridge
  • Qualified 1986
  • Admitted in Republic of Ireland (non-practising)
  • Advocaat bij de Balie te Brussel
  • Partner 1996
  • Managing Partner 2004 -2011
  • Senior Partner 2018

What others say

"She [Pat Treacy] makes competition law seem black and white through her clear and practical advice." Chambers and Partners 2020
Pat Treacy "is a very calm and canny tactician" Chambers and Partners 2020
Pat Treacy is "a pleasure to work with." Legal 500 2020
"Pat Treacy and Sophie Lawrence are both excellent and strong at handling IP-related matters crossing over with competition law; together they make an outstanding team" Legal 500 2020
"Pat Treacy is considered a leader in the field and a terrific lawyer who is savvy, experienced and practical" Who's Who Legal 2020
Pat Treacy assists clients with both contentious and non-contentious competition law matters. She represents defendants in abuse of dominance cases and market investigations. Treacy also acts for life sciences clients on the competition law aspects of patent cases. She “provides highly bespoke advice in a measured and digestible way and is a pleasure to deal with.” Chambers and Partners 2019
Pat Treacy at Bristows is "amazingly good" applaud peers who consider her "clearly one of the leading practitioners" in the competition market. According to one source, she is "one of the go-to competition counsel in Europe for IP and innovation-related matters". Who's Who Legal 2019
"Practice head Pat Treacy is recommended as ‘the go-to competition counsel in Europe for IP innovation related matters, delivering outstanding work’." Legal 500 2019
Pat Treacy advises clients from the TMT and life sciences sectors on the interface between competition law and IP. Commentators describe her as a "strategic thinker who is very business like, gets straight to the point and provides clients with options." She acted for Cousins Material House on a claim of abuse of dominance brought against Swatch. Chambers and Partners 2018
"‘instinctive litigator’ Pat Treacy successfully defended Google in High Court proceedings regarding the client’s dominant position in the area of online mapping. Additionally, Treacy acted for Google in the high-profile claims regarding the client’s practice of online shopping and price comparison services." Legal 500 2017
"Practice head Pat Treacy is advising longstanding client Sony Interactive Entertainment Europe on resisting a potential interim injunction application in relation to abuse of dominance allegations." Legal 500 2017
"Pat Treacy is described by clients as 'a fantastic lawyer: she has a good understanding of business dynamics, is always calm and collected and provides advice in a digestible way.' She acts on a broad range of competition law mandates, with particular expertise in matters at the intersect of IP and competition law." Chambers and Partners 2017
"...competition expert Pat Treacy." Legal 500 2016
"Practice head Pat Treacy, who ‘skilfully translates the complexities of competition law into pragmatic legal advice’, advised Kimberly-Clark during an investigation launched by the Groceries Code Adjudicator." Legal 500 2016
"Pat Treacy is the head of department at Bristows LLP and has particular knowledge of cases which span competition law and IP law. She has sector-specific knowledge within the life sciences and TMT sectors." Chambers and Partners 2016

Recommended For

Competition Law and Information Technology Law
Best Lawyers™ UK 2021

Competition Law
Chambers and Partners Global 2020

Competition Law: Litigation
Chambers and Partners Global 2020

Competition Law
Chambers and Partners 2020

Competition Law: Litigation
Chambers and Partners 2020

Competition Law
Chambers and Partners Europe 2020

Competition Litigation
Chambers and Partners Europe 2020

EU and Competition
Legal 500 2020

Competition litigation (leading Individual)
Legal 500 2020

Competition litigation
Legal 500 2020

Who’s Who Legal: Leading Individual 2020

Who’s Who Legal: Thought Leader 2020

Competition/ European Law: Non-contentious
Chambers and Partners 2019

Competition and Antitrust: Leading practitioner
Expert Guides: Women in Business Law 2019

Who’s Who Legal Worldwide Thought Leaders 2019

Pharmaceuticals and biotechnology
Legal 500 2017

Competition Team of the Year
The Lawyer Awards 2017

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