Gary Oliver
Senior Clerk
+44 (0) 207 822 7325
Tristan is widely recognised across his core practice areas of public, regulatory and competition law. He also has a busy employment law practice particularly in discrimination law. He is currently one of the Standing Counsel to the Competition and Markets Authority.
"A pleasure to work with and highly sought after, Tristan is astute when it comes to strategy, very good with clients and very good on his feet."- Legal 500, 2024
Tristan’s practice covers the full range of public and regulatory law, from human rights law through to technical sectoral regulation. The current edition of Chambers & Partners notes that he is sought after in “difficult administrative and public law disputes”.
Many of Tristan’s cases raise human rights and civil liberties issues. He recently appeared in the Court of Appeal as Advocate to the Court in Barking and Dagenham LBC v Persons Unknown [2022] EWCA Civ 13 concerning injunctions against travellers. He is also a specialist in EU law, which is a feature of many of the cases summarised below.
Tristan has extensive experience of education law, including special educational needs, student discipline, and regulation of higher education providers (e.g. Bloomsbury v Office for Students [2021] EWCA Civ 800). He has acted in planning judicial reviews, including obtaining an unusual injunction against Transport for London. In environmental law, his practice recently included a judicial review concerning trade in endangered species, Glass Eels Ltd v SSEFRA [2023] EWHC 336.
In social security law, Tristan has acted in the Upper Tribunal and the Court of Appeal, including representing a claimant in the test case SSWP v Jeffrey [2016] EWCA Civ 413. In immigration law, he has acted in judicial reviews of immigration decisions as well as in human trafficking claims. He has acted in several cases concerning prisoners’ rights, from judicial reviews of decisions regarding particular prisoners to the wider challenge to prisoner voting legislation in R (Chester) v SSJ [2013] UKSC 63. He has also acted in cases concerning data protection rights, most recently R (Open Rights Group) v SSHD [2021] EWCA Civ 800.
Tristan has wide experience of media and telecoms regulation. He recently led Ofcom’s team in a judicial review regarding the BBC’s online services (Radiocentre Ltd v Ofcom [2023] EWHC 1977). He was part of the claimant’s team in a challenge to the Advertising Standards Authority in R (Cityfibre Ltd) v ASA [2019] EWHC 950. Further details of Tristan’s telecoms experience, including cases involving Ofcom, can be found in the telecoms section of this page.
Tristan has advised on many energy matters, including oil and gas licensing and electricity and gas distribution and supply. He has acted both for and against Ofgem in litigation (including in R (Infinis) v Ofgem [2013] EWCA Civ 70). He has also acted in several cases concerning pharmaceutical regulation, including R (Blue Bio) v SSH [2016] EWCA Civ 554, as well as several cases in the Competition Appeal Tribunal in 2021-2023.
Details of Tristan's recent judicial reviews against the CMA can be found on the competition section of this page.
A selection of recent cases appears below.
“All of Tristan's work is really impressive. He's the barrister I would always wish to instruct for pretty much any regulatory issue, contentious or non-contentious.”
Chambers and Partners, 2023
“He is able to pick up any brief and master it in no time.”
Chambers and Partners, 2023
“He's a very good advocate; very good on his feet.”
Chambers and Partners, 2023
“He can absorb incredible amounts of detail and is excellent at witness handling.”
Chambers and Partners, 2022
“Really practical and an excellent advocate; he turns his hand to new things very easily.”
Chambers and Partners, 2021
“A great advocate - clear, knowledgeable and persuasive.”
Chambers and Partners, 2021
“A polite but deadly cross-examiner.”
Legal 500, 2021
“Makes very complex cases easy to understand, and helps the Tribunal get directly to the key issues in the case.”
Legal 500, 2021
Acted for Which?, the Consumers' Association, intervening in this Supreme Court case regarding authorised push payment fraud.
Led the counsel team successfully defending the Secretary of State for the Environment, Food and Rural Affairs in a case concerning trade in endangered species.
Tristan led the counsel team for Ofcom in successfully defending a wide-ranging challenge regarding Radio One Dance, a new BBC online radio stream.
Tristan acted as part of the team for British Sugar in this important case about EU state aid law as applied under the Northern Ireland Protocol; and about subsidies under the EU/UK Trade and Cooperation Agreement.
Tristan was Advocate to the Court of Appeal in this wide-ranging decision regarding the courts' power to make injunctions against Persons Unknown.
Tristan acted for Dr Bell, a senior doctor, intervening in this high profile Court of Appeal decision concerning the circumstances in which children may consent to receive puberty-blocking drugs.
Junior counsel for the Secretary of State in a challenge to the lawfulness, under retained EU law, of the so-called "immigration exemption" to the Data Protection Act.
Junior counsel in judicial review proceedings brought by a higher education provider in relation to the OfS's refusal to register it under the new regulatory regime under the Higher Education and Research Act 2017. The case was the first challenge to the OfS and raised issues of lawful delegation, the duty to consult, the public sector equality duty, A1P1, discrimination under Article 14 ECHR and proportionality.
High Court claim for Francovich damages arising out of the Secretary of State's failure to regulate medicines in accordance with the Medicinal Products Directive.
Tristan acted for the PSA Executive in what the PSA has called a “landmark case” against a provider offering a platform for premium rate services such as games and adult content. The PSA Tribunal found that Veoo knowingly failed in its due diligence obligations, failing to take adequate steps to ensure that consumers had opted in to the services provided by those companies using its platform. The Tribunal imposed an unprecedented £600,000 fine and prohibited Veoo from providing premium rate services for two years.
Judicial review regarding the test to be applied by the ASA when deciding whether an advertisement is misleading. The advertisements in question concern fibre broadband.
Represented Westminster City Council obtaining an interim injunction which prevented Transport for London from commencing works on a cycle superhighway. Tristan was also junior counsel in the subsequent judicial review ([2018] EWHC 2402 (Admin)).
Tristan represented the Claimant in a five-day human rights damages action for alleged breaches in failing to recognise that the Claimant was a potential victim of human trafficking, and for failing to take steps to protect him.
Tristan is a leading competition law barrister. He is one of the standing counsel to the Competition and Markets Authority and has appeared in many of the preeminent cases over recent years.
Tristan’s experience of competition enforcement appeals, for the regulator and for appellants, includes challenges to decisions on smart meters (2010), tobacco (2011), pre-cast concrete (2020), liothyronine (2022), prochlorperazine (2023) and hydrocortisone (2023).
In private damages claims Tristan has acted for claimants and defendants in many major disputes, including in litigation regarding sports data, interchange fees, trucks, power cables, bearings, rubber, car safety systems, copper tubes, air freight, accreditation services, and forex.
Tristan has also acted in several collective proceedings. He acted for the claimant in the first application for a Collective Proceedings Order (Pride) and he represented Which? in its intervention in the Supreme Court in Merricks. He recently acted for the class representative obtaining a CPO against Google, and is currently instructed in several other collective claims both for claimants and defendants.
In the merger space, Tristan’s experience includes acting for Ryanair in its challenges to the CMA, as well as more recently for the CMA in the two high-profile technology sector merger challenges in 2020 (Sabre/Farelogix) and 2022 (Facebook/Giphy).
Tristan also has state aid and subsidy experience. He acted as lead counsel for the claimants in the 2019 state aid challenge to the capacity market (which settled). In 2022 he was a part of the team acting for British Sugar in a challenge to import tariff rules.
A selection of Tristan's recent cases appears below.
“Tristan is extremely highly sought after and very experienced.”
Chambers and Partners, 2021
“Tristan is one of the standouts and a star of the future. He's got particular expertise in class action and large-scale multiparty cases. He's very easy to deal with and responsive and hard-working.”
Chambers and Partners, 2023
“He is pragmatic. He just does not miss anything in a case: everything is dealt with very thoroughly.”
Chambers and Partners, 2022
“Very approachable, great to work with and humble.”
Legal 500, 2021
“A polite but deadly cross-examiner able to be very thorough without tripping into pedantry.”
Legal 500, 2021
“Really eloquent and persuasive, he is a clever, articulate and calm advocate.”
Chambers and Partners, 2020
“He gets stuck in and is very thorough and diplomatic. It is always fine to put him in front of clients because he has always thought about all of the issues and is well prepared.”
Chambers and Partners, 2020
Tristan led a team of six barristers in a six-week trial for the CMA, against five teams of opposing counsel, in a case concerning an alleged agreement regarding prochlorperazine. Judgment is awaited.
Tristan acted for the CMA defending a judicial review concerning the CMA's power to require companies outside the UK to provide it with documents.
Tristan acted for Betgenius in defending a standalone competition claim regarding sports betting data. The case settled early in the trial.
Tristan acted for the proposed class representative in her application for a collective proceedings order against Google.
Tristan acted for the CMA in this challenge by Meta against the CMA's decision to prohibit Meta's acquisition of Giphy. The case raises important questions regarding the assessment of potential competition.
Tristan acted as part of the team for British Sugar in this important case about EU state aid law as applied under the Northern Ireland Protocol; and about subsidies under the EU/UK Trade and Cooperation Agreement.
Junior counsel for the CMA in this challenge brought by Sabre Corporation for review under section 120 of the Enterprise Act 2002 of the CMA's decision preventing a merger between two companies active in the provision of IT solutions to airlines. The case raises issues relating to the jurisdiction of the CMA in respect of foreign companies.
Junior counsel for the CMA in cartel penalty appeal raising important questions about the scope and proper application of the Authority's powers.
The case is brought on behalf of 46.2 million consumers, for losses running to several billion pounds. It is the first application for certification under the new collective action regime to have reached the Supreme Court. The Supreme Court rejected Mastercard’s appeal. Tristan acted for the intervener, Which?.
Competition Appeal Tribunal decision regarding whether an additional party in a cartel damages claim is entitled to sue the claimants for a negative declaration.
Decision on applicable law in multi-national damages litigation.
Represented the Claimant in applications for an injunction and in preliminary issue trial on the question of whether the Defendant is an undertaking for the purpose of section 18 of the Competition Act 1998.
Tristan is recognised as a leading junior in telecoms law, which brings together his EU, regulatory and competition expertise. He has appeared in many of the main cases over the last decade, and is frequently instructed by Ofcom as well as by industry. A selection of recent cases appears below.
“He is very easy to work with and provides intelligent, practical advice.”
Chambers and Partners, 2023
“He is very effective.”
Chambers and Partners, 2023
“He is a very clever person, a good advocate, and someone who is very pleasant to work with.”
Chambers and Partners, 2021
“He pays meticulous attention to detail and is extremely clever.”
Legal 500, 2021
“A smooth character, who is responsive and quick-thinking.”
Chambers and Partners, 2020
“He knows the telecoms industry really well, is very sharp-witted and his drafting is excellent.”
Chambers and Partners, 2019
Tristan led the counsel team for Ofcom in successfully defending a wide-ranging challenge regarding Radio One Dance, a new BBC online radio stream.
Tristan acted for the PSA Executive in what the PSA has called a “landmark case” against a provider offering a platform for premium rate services such as games and adult content. The PSA Tribunal found that Veoo knowingly failed in its due diligence obligations, failing to take adequate steps to ensure that consumers had opted in to the services provided by those companies using its platform. The Tribunal imposed an unprecedented £600,000 fine and prohibited Veoo from providing premium rate services for two years.
Judicial review regarding the test to be applied by the ASA when deciding whether an advertisement is misleading. The advertisements in question concern fibre broadband.
Representing Vodafone in proceedings regarding the “5G” spectrum auction.
Junior counsel to Ofcom in challenges to its Business Connectivity Market Review.
Junior counsel to the Altnets in appeals to the CAT relating to BT’s charges for Ethernet services.
Counsel for Hutchison 3G in a challenge to Ofcom's decision on spectrum licence fees.
Junior counsel to Ofcom in the ‘number porting’ appeal.
Junior counsel to Ofcom in the ‘VULA margin’ appeals.
Junior counsel for the interveners in appeals to the CAT and the Court of Appeal relating to BT’s charges for partial private circuits.
Tristan has experience of a wide range of employment disputes, covering Employment Tribunal and High Court cases.
Tristan has particular expertise in equal pay and the Equality Act. He regularly appears in the Employment Appeal Tribunal, and he acted as sole counsel for the successful claimant in the leading Court of Appeal case on discrimination causing stress at work. He has also acted in several high profile disability discrimination claims.
A selection of recent cases appears below.
Decision regarding the doctrine of state immunity in an employment context, and in particular its application to United States military bases in the United Kingdom.
Tristan represented the Appellant in this EAT appeal regarding the correct approach to an application to add an individual respondent to an employment claim after expiry of limitation.
Tristan represented the Claimant in the EAT appeal concerning the steps which a Tribunal is obliged to make to adjust the pre-trial process to enable a disabled litigant fully and fairly to participate in the proceedings.
Tristan represented the Claimant in this EAT appeal concerning out of time amendments to pleadings.
Tristan represented the Appellant in the Court of Appeal in an important decision regarding the meaning of a "provision, criterion or practice" in discrimination law, and the extent to which a one-off act may qualify.
Tristan represented the Appellant in the Employment Appeal Tribunal in a case concerning the treatment of medical evidence in an application to extend time for bringing a claim.
Tristan represented the Appellant in a case before the Employment Appeal Tribunal concerning the scope of the 'reasonable adjustments' duty. The EAT held that being less efficient than non-disabled persons may constitute a relevant disadvantage within the Equality Act 2010, and that reasonable adjustments may include adjustments to make the disabled person more efficient.
EAT decision regarding the threshold for striking out a claim.
Tristan acted in two appeals before the Employment Appeal Tribunal concerning victimisation discrimination and the Police Conduct Regulations.
Represented the claimant in landmark Court of Appeal case concerning damages for stress at work in a discrimination context.
VAT registration number: 911952430
Barristers regulated by the Bar Standards Board
Gary Oliver
Senior Clerk
+44 (0) 207 822 7325
Derek Sutton
Deputy Senior Clerk
+44 (0) 207 822 7327
Adam Sloane
Deputy Senior Clerk
+44 (0) 207 822 7326
Dean Tolman
Clerk
+44 (0) 207 822 7331
Billy Brian
Clerk
+44 (0) 207 822 7339
Marc Armstrong
Clerk
+44 (0) 207 822 7330
Adam Fuschillo
Clerk
+44 (0) 207 822 7329
Danny Compton
Clerk
+44 (0) 207 822 7338
Sophie Reeve
Clerk
+44 (0) 207 822 7324
Rio Sully
Clerk
+44 (0) 207 822 7299