Jack Williams

Call: 2015 | 2020 (Ireland) | 2020 (Northern Ireland)

Custom PDF


MA (Cambridge) – First Class; BCL (Oxford) – Distinction; BPTC (BPP) – Outstanding

Custom PDF

Which sections would you like to include in your PDF download?


Jack practises across all Chambers’ specialisms, with a particular focus on Competition Law, EU Relations Law, Procurement Law and Public Law. Legal 500 ranks him as a “rising star: tier 1”. He has been instructed in significant cases at all judicial levels:

  • Competition Law: Jack acts for the applicants in two major abuse of dominance cases before the General Court, T-286/09 RENV Intel v Commission and T-334/19 Google v Commission (Adsense). He was the respondent’s counsel in the UK’s first opt-out class action case, Gibson v Pride [2017] CAT 9. He also acted for the FCA in its first competition enforcement decision (asset management).
  • EU Relations Law: Jack has been at the forefront of all matters in connection with Brexit and the UK’s new relationship with the EU post Brexit, EU Relations Law. He is the founder and editor of www.eurelationslaw.com and is a co-editor (with Professors Mark Elliott and Alison Young) of a collection entitled: “The UK Constitution after Miller: Brexit and Beyond”. He has been instructed in a range of Brexit litigation, including Miller (Article 50 litigation), Eurotunnel v Secretary of State (Brexit no deal ferry contracts), and Heathrow v Treasury (decision to remove tax reliefs at the end of Brexit transition period).
  • Procurement Law: Jack has been instructed on both claimant and defendant sides in major procurement litigation. For example, he acted for Eurotunnel in relation to its expedited procurement and state aid law challenges to the award of Brexit ferry contracts (Eurotunnel v Secretary of State for Transport [2019] EWHC 419 (TCC)), and was instructed by Arriva in relation to the rail franchising litigation (appearing both at High Court and Court of Appeal levels: [2019] EWHC 2047 (TCC), [2019] EWHC 2922 (TCC) and [2019] EWCA Civ 2259).
  • Public Law: Notable reported cases include R (Miller and Dos Santos) v Secretary of State for Exiting the European Union [2017] UKSC 5, where Jack acted for one of the interested parties in the Article 50 litigation at both Divisional Court and Supreme Court levels). Before qualifying as a Barrister, Jack was a College Lecturer at Brasenose College (University of Oxford) where he taught Administrative Law and Constitutional Law.

Jack is a graduate from the University of Oxford (Hertford College) with a Distinction in the BCL Masters in Law (ranked 2nd in the year). Before that, he graduated from the University of Cambridge (St Catharine’s College) with a First Class Degree in Law. Jack was awarded University prizes for coming top of the year in Administrative Law (Cambridge), Labour (Employment) Law (Cambridge), and Comparative Public Law (Oxford). Jack was the recipient of Gray’s Inn’s top scholarships for Bar School and Pupillage.

Jack is a member of the Attorney General’s C Panel, enabling him to undertake civil and EU work for all government departments. In addition to England and Wales, Jack is called to the Bars of Ireland and Northern Ireland, meaning that Jack retains rights of privilege to advise on matters of EU law and rights of audience before the EU Courts.