Oliver Assersohn KC

: +44 (0)20 7691 2424
: oliver.assersohn@xxiv.co.uk
: Contact clerks
: Add to portfolio
: Download cv (pdf)
: Download vCard
: LinkedIn

Oliver Assersohn KC is a leading financial services and commercial barrister. The independent legal directories for 2024 state:

Oliver is “incredibly intelligent and has a particularly effective written style. He is a real team player and can be depended on in high-stakes litigation” (Commercial Litigation, Legal 500 2024);
Oliver “brings commerciality as well as excellent analytical skills to the team” (Banking and Finance, Legal 500 2024);
Oliver is “client friendly” and “often in the high-profile, reported cases” (Financial Services, Chambers & Partners 2024); and
Oliver is a “go-to counsel for financial services regulatory matters” (Financial Services Regulation, Legal 500, 2024).

Previous entries in the directories over the years have included the following descriptions: “first rate”, “clearly outstanding”, “an impressive advocate”, “a robust advocate when needed”, “highly personable and a dream to work with”, “a delight to work with” and that he “will work tirelessly in support of the client’s case”.

Oliver is called to the Bar of England and Wales, undertakes offshore work and in Dubai is a registered DIFC (Part II) practitioner. Further details of Oliver’s areas of expertise, endorsements and publications are contained in the tabs below.

Expertise

Financial Services Regulation

Oliver is a leading financial services regulatory silk and has acted in many of the leading cases in England and Wales as well as offshore including in Guernsey, Jersey and the DIFC. The reviews from the directories copied below speak for themselves but a number highlight Oliver’s skilful advocacy, ease to work with, commerciality and his ability to find solutions to complex problems.

Over his 20 years in practice he has advised and acted as advocate for a large number of firms and individuals of all seniority from traders to CEOs and in cases involving both the FCA and PRA. Oliver recently assisted a leading industry body with the response to the consultation to amend the Lloyd’s Enforcement Byelaw.

Oliver is a founder-member of the Financial Services Lawyers Association and heads the Executive Committee as well as publishing on various financial services matters (see publications). He is often asked to give talks to leading firms of solicitors on financial services regulatory issues.

Some sample matters are set out below (a number are confidential or referred to anonymously):

Cases involving individuals

FCA v a CEO (ongoing): Acting for the former CEO of a major listed company. The FCA’s case is that the CEO was knowingly concerned in the company breaching various rules by making false statements to the market and failing to act with integrity. The FCA’s case is not accepted and the matter is presently before the Upper Tribunal.
FCA v Demetrios Hadjigeorgiou (ongoing): Acting for former CEO of discretionary fund management business in reference to the Upper Tribunal of FCA’s decision to impose prohibition order and fine on Mr. Hadjigeorgiou.
PRA v a CEO: Acted for former CEO facing PRA disciplinary proceedings.
FCA v a Trader: Successfully persuaded Regulatory Decisions Committee to allow an application for authorisation from a trader previously dismissed for gross misconduct from his previous employer. Result allowed trader to resume his career.

Cases involving firms

X Ltd v Y: Example of one of several matters in which Oliver has been involved involving loans alleged to be unenforceable due to an alleged breach of the perimeter and application to enforce pursuant to the Financial Services and Markets Act (2000).
(Alleged) crypto-asset exchange provider: Advising whether a licence required when acting as crypto-asset exchange provider including whether the firm was acting in the course of business in the United Kingdom.
Shop Direct v The Official Receiver [2023] EWHC Civ 367: Acted for the Claimant in this Part 8 claim involving complex questions of law regarding the interpretation of the FCA Handbook.
FCA v Firm W: Advised in respect of FCA investigation surrounding systems and controls in respect of market abuse, personal account dealing and conflicts of interests.
FCA v Firm X (2022): Advised listed company under severe time-restrictions if FCA’s interpretation of complex rules and objection to a very high value deal was correct and, if not the appropriate method of challenge.
Crypto-claims (2022): Advised as to viability of a range of potential claims against crypto-platforms.
Firm Y v FCA (Regulatory Transactions Committee, Upper Tribunal, 2021): Acted for firm in Upper Tribunal applications for suspension of FCA requirements and for privacy.
FCA v Firm Z (Regulatory Decisions Committee, 2021): The FCA sought to impose an immediate variation of client’s permission which would have destroyed its business. Successfully persuaded the initial decision maker to change her mind thereby avoiding a disastrous outcome for client.

Commercial Litigation

Oliver has extensive and wide-ranging experience of commercial litigation and he is particularly well-known for his experience acting in banking and financial services related cases (for example cases dealing with questions of: whether the regulatory perimeter has been breached; the enforceability of financial services agreements; the interpretation and the effect of financial services regulatory rules; and, liability of third parties including bond issuers, brokers, underwriters and solicitors). Oliver has acted for parties seeking to judicially review decisions of regulatory bodies and the Financial Ombudsman Service. Oliver also has extensive experience of acting for parties in cases involving allegations of fraud (including authorised push payment fraud), mis-sold investments, breach of contract and professional negligence.

The reviews from the directories copied below speak for themselves but a number highlight Oliver’s skilful advocacy, ease to work with, commerciality and his ability to find solutions to complex problems. Some sample matters are set out below (a number are confidential or referred to anonymously):

Aamanya AG v Ballinger & Co Ltd: Acting for claimant in respect of unilateral close out of forex trades (see https://www.law360.com/articles/2261347/forex-trader-sued-for-unilaterally-closing-trades).
Well-known social influencer v athletic apparel retailer (2025): Acted for well-known and successful social influencer in claim against a retailer for allegedly backing out of a US$1m promotional campaign.
Melia & Anr v Tamlyn & Son Ltd [2024] EWHC 3002 (Ch): Acted for Claimants in claim for breach of contract and professional negligence. A critical issue in the case was establishing that a crucial letter relied upon by the Defendant had not in fact been sent: a point that was established through cross-examination and legal submissions. For comment on this interesting case read more here and here.
Shop Direct v The Official Receiver [2023] EWHC Civ 367: Acted for the Claimant in this Part 8 claim involving complex questions of law regarding the interpretation of the FCA Handbook.
Akhmedova v Akhmedov & Ors: Instructed close to trial by son being sued by his mother for c. US$100m. Complex legal issues re the Insolvency Act (1986) and Matrimonial Causes Act (1973). Case highly sensitive and attracted significant press attention. As sole counsel, successfully argued at the search order return date that the propriety of the order should be examined at trial together with questions of costs (which the Claimant sought in the sum of £242,000) ([2020] EWHC 3006 (Fam)). Subsequent trial (led) [2021] EWHC 545 (Fam) (claim succeeded).
Liberty v Tancred [2018] EWHC 2707 (Comm): Claimants sole counsel in a 7-day trial of a preliminary issue concerning the sale of an IFA business. Complex legal issues regarding limitation. Demanding cross-examination and Claimant largely successful and awarded its costs.
Liberty v Tancred [2019] EWHC 2921 (Comm): Successfully obtained summary judgment. Complex arguments regarding construction, issue estoppel and res judicata.
Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors [2018] EWHC 496 (Ch); [2019] EWCA Civ 2074: Claimant’s sole counsel at trial and in the Court of Appeal – in both, successfully argued an assignment of a loan book should be declared void on grounds of fraud (an insolvency case). Trial judge described case as “important and urgent”. A further challenge was that an imprisoned litigant in person Defendant could not attend the trial.
X v a Foreign State (confidential): Acted for international conglomerate against foreign government for debt and breach of contract for c. US$60m. Involved complex questions of construction of the agreement, termination and the consequences of the same. Successfully settled pre-action.
Y v Z: Acted for Claimant in multi-million euro claim by provider of e-money vouchers against acquiring bank of the Claimant.
A Club v the Club’s former President: Acted for former president of a Club accused of acting in breach of the Club Rules and/or his other duties in authorising various payments.
R (on the application of Zai Corporate Finance Ltd) v (1) AIM Disciplinary Committee (2) London Stock Exchange [2017] EWCA Civ 1294: Acted for Nomad facing disciplinary proceedings who applied for judicial review of the decision that the disciplinary proceedings be heard in private.
Estate agent commission cases: Acted in numerous cases involving question of enforceability of the contract under the Estate Agents Act (1979) following successful defence of claim on the ground the contract was unenforceable in the Court of Appeal case of The Great Estates Group Ltd v Digby [2011] EWCA Civ 1120.
Judicial review: Acted in a number of cases involving challenges to the Financial Ombudsman Service including R (on the application of iDealing.com Ltd v FOS [2024] EWHC 847 (Admin) and the earlier related case of Kith (see [42] of iDealing judgment) which was settled by consent and required the FOS to pay a substantial portion of iDealing’s costs.
Oliver has represented numerous States and is presently acting for an African country seeking repatriation of Roman ruins taken to England in the 19th century.
Oliver also acted for a number of years for the second largest organisation in Ethiopia which successfully defeated a US$30m claim on grounds of forum non conveniens (Court of Appeal judgment, Mengiste v EFFORT & Ors [2017] EWCA Civ 1326).

Insolvency

A v B [2025]: Acted for a former director of a company in liquidation and another company that payments were transactions at an undervalue within the meaning of s. 238 the Insolvency Act 1986 (“IA”), alternatively preferences within the meaning of s. 239 of IA 1986, alternatively were void having been made without the authority of the Company. Case settled on favourable terms shortly before trial.
Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors, Court of Appeal [2018] EWHC 496 (Ch): Acting for joint liquidator in respect of a declaration an assignment was void under s. 127 of IA and that it should be set aside under s. 238 and s. 423 of the IA (see https://www.law360.com/articles/1217949/convicted-illegal-lender-fights-to-stay-in-asset-seizure-suit).
X v Y (Chancery Division, August 2017): Acted for trustee in bankruptcy in obtaining an urgent freezing injunction before Mr. Justice Mann and instructed in the substantive underlying claim for breaches of the IA 1986.
X v Z (2016): Instructed on behalf of financial institution in bankruptcy proceedings against a debtor.
Akhmedova v Akhmedov & Ors, instructed close to trial by son being sued by his mother for c. US$100m. Complex legal issues re the Insolvency Act (1986) and Matrimonial Causes Act (1973). Case highly sensitive and attracted significant press attention. As sole counsel, successfully argued at the search order return date that the propriety of the order should be examined at trial together with questions of costs (which the Claimant sought in the sum of £242,000) ([2020] EWHC 3006 (Fam)). Subsequent trial (led) [2021] EWHC 545 (Fam) (claim succeeded).

Crypto & Digital Assets

(Alleged) crypto-asset exchange provider: Advising whether a licence required when acting as crypto-asset exchange provider including whether the firm was acting in the course of business in the United Kingdom.
Crypto-claims (2022): Advised as to viability of a range of potential claims against crypto-platforms.

Oliver is co-author of the disputes chapter in Crypto and Digital Assets Law and Regulation published by Sweet and Maxwell in December 2023.

ADR

Oliver is a member of the Swiss Arbitration Association and Associate Member of the Chartered Institute of Arbitrators. The nature of the work means that it necessarily must remain anonymous but some examples include:

A, B, C: Acted for several major banks in LCIA Arbitration in application for urgent interim relief.
Cengiz v Libya (ICC Arbitration, 2018): Case leader for Libya defending a US$302m claim for breaches of a bilateral investment treaty arising from the Arab Spring. Highly sensitive and complex legal issues regarding jurisdiction, breach and causation. Extensive and challenging cross-examination of 4 lay and 4 expert witnesses. Favourable outcome: parts of claim dismissed and award for US$51m cf. US$302m claimed.
Acting for a fund alleging breaches of a settlement deed with a former founder-director (matter successfully compromised).

DIFC and ADGM

Oliver is a registered DIFC (Part II) practitioner and has been commissioned by Elgar Publishing to write: “Financial Services Law in the DIFC and ADGM” (publication expected 2025). Recent representative matters in the DIFC and ADGM include:

C v D [2025]: Advice in respect of tens of millions of pounds frozen by DIFC banks.
2024-2025: Acting in DIFC for Claimant in successful application for proprietary injunction, alternatively freezing injunction (leading Tom Stewart Coats).
2024-2025 – ongoing: Advising in relation to the enforceability of a judgment of a separate jurisdiction in the DIFC.
2024: Acting for firm in ADGM seated-arbitration which had suffered serious damage by reason of former executive’s breaches of various restrictive covenants. Successfully secured settlement (leading Tom Stewart Coats).
2024: Advising, in the context of financial services regulation, on the correct interpretation of Article 86 of DIFC Law No 1 of 2004 and, in particular, the meaning of a person being “knowingly concerned” in the contravention of another.
2023: Successfully argued that a judgment creditors’ application for a Part 50 Order should be set aside on jurisdictional grounds thus avoiding the need for the client to provide private financial information and be cross-examined.

Recommendations

‘He is an excellent advocate who provides insightful opinions that add real value.’ Financial Services, Chambers & Partners 2026

‘He is a significant operator and continues to do major work in this space.’ Financial Services, Chambers & Partners 2026

‘Oliver is approachable and friendly. He is excellent on market abuse and financial crime.’ Financial Services, The Legal 500 2026

‘Oliver is a formidable and deeply knowledgeable barrister in this area’ Banking and Finance, The Legal 500 2026

‘Oliver deals with very complex issues adeptly. His written work is clear and concise. He is a pleasure to deal with.’ Commercial Litigation, The Legal 500 2026

“He is great technically and is also very approachable and client-friendly.” “He is often in the high-profile, reported cases.” Financial Services, Chambers & Partners 2024

‘Oliver is an outstanding team player and brings commerciality as well as excellent analytical skills to the team. He is a go-to counsel for financial services regulatory matters.’ Financial Services Regulation, The Legal 500 2024

‘Oliver is incredibly intelligent and has a particularly effective written style. He is a real team player and can be depended on in high-stakes litigation.’ Commercial Litigation, The Legal 500 2024

‘Oliver is an outstanding team player and brings commerciality as well as excellent analytical skills to the team.’ Banking and Finance, The Legal 500 2024

“Oliver Assersohn is regarded very highly.” “He is very user-friendly and very experienced in financial services regulation.” “He is extremely knowledgeable about financial regulation in the UK and is clearly outstanding.” Financial Services, Chambers & Partners 2023

“Oliver is very pleasant to work with and extremely personable. He is bright and committed; and understands how the FCA thinks. He is a robust advocate when needed.” Financial Services Regulation, Legal 500 2023

“Technically brilliant, very hard working and a delight to work with.” Banking and Finance, Legal 500 2023

“Amiable and smart he produces superb written work and is a considered and impressive advocate. Wonderful to have in your team.” Commercial Litigation, Legal 500 2023

“He’s technical but also sensitive to business and commercial implications – he weighs in in a way that furthers business goals.” “An ambitious and skilled advocate.” Financial Services, Chambers & Partners 2022

“Oliver takes ownership of a case from the outset and will work tirelessly in support of the client’s case. He is very bright, and has significant FCA expertise.” Financial Services Regulation, Legal 500 2022

“A superbly able junior, if there is an answer to a problem he will find it.” Banking & Finance, Legal 500 2022

“Oliver has a rare mix of commercial acumen, empathy and wide-ranging communication skills which enable productive engagement at all levels.” Commercial Litigation, Legal 500 2022

“An impressive specialist in FCA enforcement-related matters.” “He’s very responsive, very easy to deal with and the quality of his advice is also very good.” Financial Services, Chambers & Partners 2021

“Highly personable and a dream to work with – slots into the team very well and a tremendous team player.” Banking & Finance, Legal 500 2021

“Technically outstanding, and very hard working and responsive – he also has very sound client management (expectation management and empathy) skills.” Commercial Litigation, Legal 500 2021

“Excellent attention to detail, good analytical skills coupled with regulatory knowledge and experience.” Financial Services, Legal 500 2021

“He is easy to get along with and thorough in his advocacy, and pitches his arguments in a respectful way to the tribunal.” Oliver is “very accessible, very user-friendly and works really well as part of the team.” Financial Services, Chambers & Partners 2020

“Very responsive and hardworking, his input is always measured and valuable”. Banking and Finance, Legal 500 2020

“Bright, well informed and has good judgement”. Financial Services, Legal 500 2020

“A highly regarded junior who is an expert at handling complex issues relating to mis-sold investments and breaches of the perimeter. Having been on secondment to the FCA, he has highly valuable insight into the workings of the regulator….”Approachable, helpful and diligent.” “A credible and hard-working advocate.” Financial Services, Chambers & Partners 2019

“Very good for fraud and financial regulatory investigations.” Financial Services, Legal 500

“Highly rated for banking and financial services disputes.” Banking and Finance, Legal 500

“His written work is always excellent, he provides clear and practical advice and he deals with clients in a very empathetic manner.” Financial Services, Chambers & Partners 2017

“Technically bright, hardworking, a team player and approachable.” Business and Regulatory Crime, Legal 500 2016

“A truly excellent barrister, who knows the ins and outs of FCA regulations.” Banking and Finance, Legal 500 2016

“A financial services and banking specialist who has a wealth of expertise in the area. He has a broad chancery and commercial practice…He is incredibly diligent and hard-working, and continues to impress with his technical knowledge.” Chambers & Partners 2016

“He has a very innate feel for the regulators’ expectations and is very good at the detail. He understands the issues and is very diligent and analytical.” Chambers & Partners 2016

“Very bright, exceptionally hardworking, personable and very practical. He really understands the FCA’s enforcement process.” Chambers & Partners 2015

“He is calm, knowledgeable, diligent and keen to assist. A pleasure to work with.” Chambers & Partners 2015

“Extremely well regarded for financial services and FCA regulatory issues.” “The barrister to go to with challenging issues.” Legal 500 2015

“An absolute delight to work with.” Chambers & Partners 2014

“Highly experienced in regulatory and FCA related matters.” Legal 500 2014

“A financial services specialist.” Legal 500 2014

“First rate.” Chambers & Partners 2013

“An enviable reputation as a leading junior in financial services law.” Chambers & Partners 2012

“The ‘knowledgeable, calm and authoritative’ Oliver Assersohn is recommended for contentious financial services work, where ‘his experience is almost unique’.” Legal 500 2012

“Highly diligent.” Chambers & Partners 2011

“Invaluable knowledge of the FSA disciplinary process.” Legal 500 2011

“Understands how the regulator lives and breathes.” Chambers & Partners 2010

: +44 (0)20 7691 2424
: oliver.assersohn@xxiv.co.uk
: Contact clerks
: Add to portfolio
: Download cv (pdf)
: Download vCard
: LinkedIn

Publications

How should you respond to an FCA intervention, Ashurst Podcast (Listen here).
Co-author of the disputes chapter in Crypto and Digital Assets Law and Regulation (Sweet and Maxwell, December 2023).
Articles in numerous publications on financial services and banking matters (e.g. JIBFL November 2015 (the proposed EU Banking Union), JIBFL July/ August 2017 (Financial services law as a sword: cutting down contracts).
Co-author the chapter of COMBAR’s paper on Brexit (January 2017) entitled “MiFID, MiFID II and MiFIR: (1) Passporting and Equivalence Regimes; (2) Brexit effect on UK financial services dispute resolution” (December 2016).
Editor of the Decision Procedure and Penalties Manual Commentary in Butterworths Financial Regulation Service (c. 40,000 words) (published March 2015).

Academic history

Charterhouse; Warwick University (BA Hons first class); City University (CPE); BPP (BVC); Queen Mother Fund Scholarship (2002-03); Blackstone Entrance Exhibition (2003)

Professional memberships

Associate member of Chartered Institute of Arbitrators
COMBAR (The Commercial Bar Association)
Founding member of FSLA (Financial Services Lawyers Association)

Business Details

VAT number:: 848847172
Registered name:: Oliver Paul Assersohn

Oliver Assersohn KC

Call 2003 | Silk 2024

Perry Brown

Morgan Williams