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.

Recognised as a leading adviser on the legal and policy issues that come up when competition law and intellectual property law meet, many of Pat’s clients are in technology rich sectors.

Pat works with clients on transactions and complex agreements (including settlement, R&D, licensing and joint venture agreements) in all sectors, with a focus on high tech and pharma/life sciences. Given the confidentiality concerns that are prevalent in innovative industries, Pat has substantial experience of advising on competition law in arbitrations, as well as before the competition authorities in Brussels and London and in Court proceedings at national and EU level.

Pat advises regularly on the competition law responsibilities of dominant companies – particularly where IP is concerned. She and her team help with competition compliance and “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 six years. This part time 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 – present
  • Managing Partner 2004 – 2011
  • Senior Partner 2018 – 2020

What others say

Clients say that "it is always a great pleasure to work with her [Pat Treacy], as she can quickly grasp topics and is able to provide very clear responses." Chambers and Partners 2021
"She [Pat Treacy] is active across an impressively broad array of competition law." Chambers and Partners 2021
Pat Treacy is an "extremely knowledgeable lawyer providing a broad perspective". Chambers and Partners 2021
"Pat Treacy shows an impeccable judgment and is exceptionally clever. She knows all there is to know about the interaction between IP and competition law." Legal 500 2021
"Pat Treacy is an astute tactician in litigation, with excellent strategic thinking. She is also accessible and great under pressure" Legal 500 2021
"Her [Pat Treacy] experience as a Deputy High Court Judge gives her a particular edge in understanding how a court will approach a case." Legal 500 2021
"Pat Treacy is a star for high tech competition cases and, in general, all cases at the interface between IP and antritrust. She is highly regarded and – in my experience – unanimously seen as one of the leading figures in Europe in this field." Legal 500 2021
"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

Recommended For

Competition Law
Chambers and Partners 2021

Competition Law: Litigation
Chambers and Partners 2021

Competition Litigation (leading individual)
Legal 500 2021

EU and Competition
Legal 500 2021

Technology, Media and Telecoms
Legal 500 2021

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 Europe 2020

Competition Litigation
Chambers and Partners Europe 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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