Professional practice
“A master of the difficult brief” who combines “razor-sharp intelligence with enormous tenacity”, Charles Ciumei KC is a highly experienced litigator known for his innovative approach in difficult and complex cases and for his strength as an advocate who can cross-examine to “devastating effect”.
He has a particular expertise in data protection, notably class actions, as well as confidential information, cyber security and cybercrime, artificial intelligence (AI) and machine learning. He also has experience of breach of confidence claims relating to algorithmic trading software. He has an in-depth understanding of IT technical matters. Charles was shortlisted for Technology and Data Silk of the Year 2022 at the Legal 500 Bar Awards. He is also currently pursuing a post-graduate course in Artificial Intelligence.
He is regularly instructed in urgent injunctions and sought out for restraint of trade and “team move” cases, particularly with an international dimension or involving jurisdictional disputes. His practice covers carried interest claims, directors’ duties, shareholder disputes, LLP/partnership disputes, and arbitration, including LCIA, JAMS, and ad hoc arbitrations. His employment work includes whistleblowing, discrimination, wrongful dismissal, and employee claims in international organisations.
- What others say
Recommended as a leading individual in both Chambers & Partners UK Bar Guide and the Legal 500 Directories. Comments in recent editions include:
Chambers UK Bar 2025
- “Charles is excellent and is one of our top picks for high-stakes matters.”
- “Charles’ commercial acumen is second to none.”
The Legal 500 2025
- “Charles’ preparing and revising of merits opinions is highly technically specific and he is relentlessly accurate in his advice.”
- “He is very diligent and has a great strategic mind.”
Chambers UK Bar 2024
- “Charles is a highly intelligent, committed and supportive barrister. He is absolutely in the trenches with you and is very focused and supportive in our cases.”
- “Charles comes up with creative ways to achieve client aims, giving firm and clear advice.”
- “You simply want Charles on your side. He digs so deep and covers every angle, being creative, skilful and incredibly commercially astute.”
The Legal 500 2024
- ‘An outstanding counsel.’
Chambers UK Bar 2023
- “Charles brings assured advice and delivers it with determination.”
The Legal 500 2023
- “He has proven to be innovative and practical in his approach, as well as highly intellectual. He is very approachable and a great communicator.”
- “A class act. He handles the room, including the judge and client, with mastery, and knows when to push and when to stop – never loses his audience. Highly recommended, particularly for cross-border matters.”
The Legal 500 2022
- “He can assimilate complex arguments and a myriad of documents with incredible speed and tenacity.”
Chambers UK Bar 2022
- “Charles is razor-sharp in court.”
The Legal 500 2021
- “He is well prepared and presents cases diligently and clearly.”
Chambers UK Bar 2018
- “Thorough and sharp but also approachable and accessible. He rolls his sleeves up and gets involved with all aspects of the case and is very good at engaging with the client and protecting their interests.”
The Legal 500, 2017
- “Practical, commercial and incisive.”
Chambers UK Bar 2017
- “His work is exceptional and very clever. He always raises his game and always gets you where you need to be.”
- “He is superb – a very clever and tenacious advocate.”
The Legal 500 2016
- “One of the cleverest and most intellectually rigorous members of the Bar, with an unrivalled work ethic.”
- Examples of notable cases
- Benyatov v Credit Suisse (2018): Acting in High Court proceedings for a former managing director of an investment bank who was wrongly convicted of espionage whilst working for the bank in Romania. He lost his livelihood and faces extradition and imprisonment if he returns from the USA to his family in the UK.
- Nuclear Risk Insurers Ltd v Gatte (2018): Acting for a nuclear insurance pool in High Court injunctive proceedings against a former employee and agent in relation to his wrongful removal and retention of confidential information.
- Comberg v VivoPower International (2018): Acting in High Court proceedings for NASDAQ listed company against multiple claims brought against it by its former CEO alleging breach of contract and claiming fees due. Parallel proceedings in Singapore.
- Dow Corning v Hupfield (2017): Acting for a leading multi-national in silicon-based technology, including anti-finger print coatings used on iPhones. High Court injunctive proceedings to isolate and recover confidential information.
- Advised investors who advanced substantial sums of money into a project to develop hybrid electric trucks for the Russian market.
- Maitland Hudson LLP v Dempsey: Acted for the defendant, a departing LLP member from a solicitors firm in High Court, Chancery Division proceedings concerning a claim about copying confidential and legally privileged information that was disclosed to the Solicitors Regulation Authority (which intervened in the proceedings). The claims included breaches of the Data Protection Act 1998, and alleged offences under the Computer Misuse Act 1990.
- A T Kearney v Oliver Wyman Ltd: Dispute between two leading US based management consultancies over a team move in Dubai (UAE). Acting for the defendant management consultancy in High Court, Queen’s Bench Division injunctive proceedings in England arising out of. The proper law of the English claim was UAE law. Jurisdiction was initially challenged under the Brussels Regulation. A variety of parallel proceedings in Dubai involving related parties.
- Advising an UHNW individual and an English company in relation to a potential claim arising out the breach of a non-disclosure agreement entered into with another individual to protect the first individual’s privacy, where both people are in the public eye. Parallel proceedings in California and Europe. The issues in particular concerned the appropriate jurisdiction of any proceedings for breach of the NDA having regard to the Recast Brussels Regulation.
- Arbitration & related court applications
Advice and appearance in LCIA, GAFTA and ad-hoc arbitrations. (Parties and details are private & confidential). Member of Employment Lawyers Association Arbitration and Alternative Dispute Resolution Group.
- Commercial dispute resolution
His general commercial practice includes carried interest claims, directors’ duties, shareholder disputes and LLP disputes (see entries below).
- Acted for a UK incorporated consultancy against a US software group (serving the energy and commodity sectors) in a Commercial Court claim for termination and other payments under a consultancy agreement, involving difficult issues of contractual construction and complex legal and factual issues concerning precisely when and how the agreement was terminated. One of the key issues in the case concerned the terms on which a multi-million dollar software licensing agreement had been concluded.
- Advised in relation to the proper interpretation of a shareholders and framework agreement in a private equity investment and a potential Commercial Court claim for rectification of the agreement. The operative provisions concern the circumstances in which substantial ‘carried interest’ payments are due on the exit from investments and the proper basis for the calculation of the payments.
- Acted for and advised Vodafone (a FTSE100 listed multi-national telecommunications and mobile phone company) in a multi-faceted dispute with one of its UK-based airtime distributors. There were injunctive proceedings in the High Court, Queen’s Bench Division brought by the distributor based on claims of misuse of confidential information breaches of contract by its former employees (who had joined Vodafone). Advised Vodafone on the termination provisions (for breach) of the distributorship agreement with the airtime distributor.
- Acted in a Commercial Court claim for a founder of a leading worldwide private equity group in claims for historical carried interest. The claims were difficult to establish because of lack of proper contractual documentation and complex issues of construction to overcome in relation to the agreements that did exist.
- Confidential Information
A very significant focus of his practice concerns the protection of confidential information, trade secrets, business secrets, and privacy across a wide range of scenarios and disputes covered. Some examples are as follows: Commercial context/employment dimension:
- Regularly instructed in claims against departing employees, executives, LLP members and partners, either individually or in team move situations to prevent the disclosure and misuse of confidential information, typically by injunction and other interim relief, such as orders for delivery up and preservation. For example:
- Acted for the claimant group (one of the UK’s largest specialist recruitment businesses providing the Infrastructure sector with permanent, contract and temporary staff) in High Court, Queen’s Bench Division proceedings. The claim was against its departing CEO and other senior employees to form a rival business by misusing confidential information and diverting business opportunities. Interim injunctive relief was successfully obtained and the substantive claim was based on breach of confidence, conspiracy, breach of contract and breach of fiduciary duty.
- He has extensive experience in heavy-weight litigation between hedge funds in claims of the alleged misuse of confidential information in algorithmic trading software (typically working as part of a multi-disciplinary team with IP lawyers), for example:
- Corbiere Limited v Mean Trading Systems: Acted for defendants in a claim brought against a start-up algorithmic trading hedge fund alleging misuse of confidential information in the software of the claimants. Proceedings brought in the High Court, Chancery Division – Intellectual Property. Parallel proceedings against Cayman Island domiciled funds and an application for security for costs against the claimants. Worked as part of a multi-disciplinary team with IP lawyers. The proceedings were subject to an extensive and highly restrictive confidentiality club or regime.
- Acted for the IKOS investment management company and Commodity Trading Advisor in relation to multi-faceted disputes concerning the algorithmic trading software developed and used by its quant fund. Acted in High Court Queen’s Bench Division, and Technology and Construction Court proceedings against former employees of the quant fund and in Chancery Division proceedings in which it was the defendant in relation to claims by one of its founders to intellectual property rights in the software. Advised in relation to related proceedings in several other jurisdictions.
B2B disputes:
- Advising in relation to a claim breach of confidence with an international dimension concerning technical and engineering information and drawings for a mining equipment manufacturer based in the USA.
- Advising in relation to claims of breach of confidence concerning land purchase and development opportunities for a nationwide supermarket chain.
Private individuals:
- Advising and acting for an UHNW individual based abroad, a member of whose close personal staff had unexpectedly left his position and that country to return to the UK in possession of a company laptop containing a large amount of confidential and private personal and business information relating to the individual and his family. This was an urgent matter requiring the utmost discretion that was successfully resolved without the need to issue proceedings, although these were fully prepared.
- Advising an UHNW individual and an English company in relation to a potential claim arising out the breach of a non-disclosure agreement entered into with another individual to protect the first individual’s privacy, where both people are in the public eye. Parallel proceedings in California and Europe. The issues in particular concerned the appropriate jurisdiction of any proceedings for breach of the NDA having regard to the Recast Brussels Regulation.
- Maitland Hudson LLP v Dempsey: Acted for the defendant, a departing LLP member from a solicitors firm in High Court, Chancery Division proceedings concerning a claim about the copying of confidential and legally privileged information that was disclosed to regulatory bodies, including the Solicitors Regulation Authority (which intervened in the proceedings).
- Conflict of laws & private international law
The focus of his work in this area typically arises out of claims for interim injunctive relief where issues of jurisdiction arise (including under the Recast Brussels Regulation), and injunctions in support of foreign proceedings (under section 25 Civil Jurisdiction and Judgments Act 1982). He is also regularly involved in multi-jurisdictional disputes, involving complex jurisdictional issues or concurrent foreign proceedings or where the substantive law of the English proceedings is not English law. Examples include:
- Dispute between two leading US based management consultancies over a team move in Dubai (UAE): High Court claim in England based entirely on UAE law, including alleged breaches of contract (governed by UAE law) article 64 of the Commercial Transactions Code, articles 120 and 127 of the UAE Labor Law, articles 246 and 282 of the Civil Transactions code. Additional issues concerning issues under articles of the UAE Civil Procedure Law and other provisions of the Commercial Law. The case concerned in part a team move between management consultancies operating in the Dubai TECOM (Technology and Media) free zone. All of the contracts in issue were subject to UAE law. Worked closely with local Dubai lawyers and independent legal experts in UAE law.
- Advising a US company providing worldwide project management and construction consulting services in relation to a very substantial team move involving the actual and potential poaching of employees in Dubai (UAE), Abu Dhabi (UAE), Hong Kong and Singapore by a competitor group headquartered in the UK. Claims under UAE and English law. Issues concerning a claim for damages for breaches of contract governed by UAE law and based on various articles of UAE Civil Code (Civil Transactions Law (Federal Law No. 5 of 1985)) including articles 246, 282, 905 and 909, as well as the Labor Code and Commercial Transactions Law. Worked closely with local Dubai lawyers.
- Acting in proceedings before the Grand Court of Cayman concerning a claim for discrimination in employment and wrongful dismissal. Substantive law Cayman law.
He is admitted to the register of practitioners of the DIFC Court (Dubai, UAE).
- Cyber Security & Cyber Crime
Increasingly instructed in this area due to his IT and computing technical background and the fact that most cyber security problems involve employees in the copying or misappropriation of business secrets or confidential information or unauthorised access to computer systems. His technical understanding of computing and IT technical matters is invaluable in this context. For example:
- Acting for a leading healthcare recruitment agency in High Court, Queen’s Bench Division proceedings for injunctive relief in relation to a team move to a competitor agency. Serious issues of breach of privacy and hacking (potential offences contrary to s.1 Computer Misuse Act 1990) in relation to the collection of evidence.
- Acted and advised a company in a case where the employee had secretly installed a virtual machine on the company servers in order to copy highly confidential proprietary software to a cloud service with the intention of misusing it.
- Advised a manufacturing company in relation to a type of ‘ransomware’ that had been installed into its automated production systems and threatened to disrupt its manufacturing process.
- Maitland Hudson LLP v Dempsey: Acted for the defendant accused of breaches of the sui generis database right (Copyright and Rights in Databases Regulations 1997), breaches of the Data Protection Act 1998, and offences under the Computer Misuse Act 1990.
- Data protection & Privacy
Examples of recent work:
- Acted for the claimant in a major class action in relation to largescale data breaches by a global social media platform (SMO (A child) v TikTok).
- Advising a UK company about data protection issues as part of the design of a mobile app for health service workers in a healthcare context, in particular issues concerning the precise identification of the relevant data controllers and around the permitted scope of processing of sensitive personal data.
- As part of the IKOS litigation in the High Court, allegations of breaches of the First, Second and Sixth Data Protection Principles. The context in which the data was acquired and used involved allegations of attempted hacking, intrusive surveillance, harassment and breach of privacy. Further issues about (i) the scope of “data” and “personal data”; (ii) the identification of the data controllers and the territorial jurisdiction of the Data Protection Act 1998 (one of the alleged data controllers was outside the UK); (iii) whether a claim for damages could be maintained in the circumstances under the Act.
- Corbiere Limited v Mean Trading Systems: High Court, Chancery Division – Intellectual Property. Case about alleged misuse of confidential information in relation to software for algorithmic trading on financial markets. Data protection issues raised by way of counterclaim by individual defendants. Allegations of breaches of the First, Second, Third and Sixth Data Protection Principles and breaches of sections 4(4) and 7 of the Data Protection Act 1998.
- Maitland Hudson v Dempsey: High Court, Chancery Division. Allegations of breaches of sections 4(4) and 55(1) of the Data Protection Act 1998 in the context of access to confidential and/or legally privileged information on computer systems. Additional issues of the identity of the alleged data controller and whether there was any civil liability in relation to the alleged breaches (particularly under section 55(1), which enacts criminal offences).
- Employment
Has been consistently ranked over many years as a leading individual by both Legal 500 and Chambers & Partners. He has considerable experience in the financial services sector and its regulatory context, including the new Senior Managers Regime, and is instructed by investment banks, private equity, venture capital and hedge funds (both UK and Cayman based funds), insurers, Lloyd’s and other brokers (including inter-dealer brokers), as well as private individuals.
Team moves/post-termination restrictions (restrictive covenants)/breach of confidence:
Has extensive experience of acting for both sides in ‘team move’ cases, i.e. both the ‘poacher’ and ‘gamekeeper’. Much of this work is in the financial services sector, e.g. GFI v Ahali (inter-dealer brokers, litigation associated with the ContiCap v GFI dispute), Worldwide Currencies v Crisp (currency brokers), Bluefin Insurance v Henderson (insurance brokers).
As a notable example, in Lonmar Global Risks Ltd v West & others [2011] IRLR 138, he successfully defended a managing director of a Lloyd’s broker who moved to a rival broker with his team. High Court, Queen’s Bench Division proceedings including a 3 week trial. Claims for conspiracy, breach of contract and fiduciary duty and damages of £2.5m. Although the individual was found to have breached his contract, he was not ordered to pay any damages to the claimants and he succeeded on his counterclaim for an unpaid bonus and indemnity costs.
His work outside of the financial services sector covers a wide range of businesses as diverse as specialist recruitment agents and international management consultancy firms. He is also regularly involved in multi-jurisdictional team moves, involving complex jurisdictional issues or concurrent foreign proceedings. For example, he is acting in a long-running dispute between two leading US based management consultancies over a team move in Dubai (UAE), where the substantive law of the dispute was UAE law and there are multiple concurrent proceedings in Dubai.
Deferred remuneration, bonus litigation and share options:
He is often instructed to advise and act in deferred remuneration claims, including complicated contractual claims for carried interest and profit share. In the hedge fund sector this frequently involves allegations of breach of remuneration provisions in an LLP agreement. These claims are frequently referred to arbitration.
- Acted for a individual investment banker in his very substantial claims against a leading international investment bank and a leading commodities firm for remuneration due under several complex profit share, employment and share option agreements. The proper law of the agreements was English law and New York law.
- Defended a FTSE100 mining company against a claim for salary and bonus by a former senior executive. The claim was sensitive because there were reputational implications for the company and CEO as well as serious allegations of wrongdoing, including dishonesty on the part of the executive.
- In the unusual bonus claim case of Herbert v JP Morgan (2012), he successfully defended the investment bank against a High Court, Queen’s Bench Division claim by an banker for a bonus based on an alleged negligent misrepresentation during the recruitment process. The case was widely reported in the media due to its striking facts, namely that the mistake in the offer documents was to put a decimal point in the wrong place, with the unfortunate result of inflating 10x the base salary. The judge accepted his submissions refused to extend the English law of negligence in this area (in contrast to the approach of the Canadian Supreme Court, relied upon by the claimant).
- Acted for the successful employees in the landmark bonus case of Fish v Dresdner Kleinwort (where the investment bank refused to pay promised bonuses following the financial crisis).
Wrongful dismissal and directors’ duties:
He is regularly instructed in substantial wrongful dismissal claims, typically involving serious allegations of wrongdoing, including dishonesty, and breach of directors’ and fiduciary duties and diverting business opportunities.
Whistleblowing (Public Interest Disclosure Act), discrimination and statutory claims:
He advises and acts in the full range of statutory dismissal and discrimination claims, with a focus on those involving claims for substantial compensation or serious reputational issues for the respondent organisation or its senior management or where there are related High Court proceedings. The focus of this work tends to be substantial whistleblowing claims. He is instructed both by investment banks and private individuals in whistleblowing litigation. Recent notable cases include:
- (2015) Advising a senior manager at the London branch of a Middle Eastern bank in relation to a PIDA claim concerning regulatory issues.
- (2015) Advising in relation to a claim by a senior manager at a UK company concerning an unfair dismissal/PIDA claim by him, specifically as to whether the disclosures were made in the public interest.
- (2015) Advising and acting for a solicitor and LLP member in relation to an appeal to the Employment Appeal Tribunal concerning the striking out of his PIDA claim on the basis of judicial proceedings immunity (the claim settled shortly before the EAT hearing).
- (2012 – 2014) Advised and acted for a Middle Eastern state energy company in two separate complex high value Employment Tribunal PIDA claims brought by two senior accountants following their dismissal. They had made alleged public interest disclosures of serious accounting irregularities. Both cases were pursued to a full hearing. The cases encompassed significant reputational and domestic political issues for the company and its senior officers and former officers: Questions were raised about the matter in the national Parliament. Both cases were successfully concluded for the company at the full hearing.
- (2012) Advised and acted for a Middle Eastern state energy company in a high value Employment Tribunal PIDA claim brought by a senior manager following his dismissal from the London office. Claim was resolved before the full Employment Tribunal hearing.
Financial Services Regulatory context:
Advising in on the potential impact of the FCA/Bank of England Senior Managers Regime on contracts of employments for senior managers.
Advising and individual banker accused of LIBOR manipulation.
Trade Unions and industrial action:
He has particular expertise in relation to collective issues involving the threat of or actual industrial action, including balloting and notification requirements, injunctions to prevent strike action and dismissals related to industrial action. Has also advised in international trade disputes between employers outside the UK and the ITF.
Agriculture:
He has unique expertise in the regulatory regime for agricultural wages and other benefits in England & Wales, including the complicated consequences of the abolition of the Agricultural Wages Act in England (but not Wales) and the impact of EU law (in particular, the decision in Bear Scotland v Fulton) on overtime and holiday pay entitlements in the agricultural sector.
Special Advocate:
He was appointed a Special Advocate by the Attorney General in 2009 and has DV (Developed Vetting) security clearance which enables him to have access to closed material in cases concerning national security.
- Injunctions, interim relief
He is recognized for his expertise in obtaining urgent interim injunctive relief in such cases and has a track record of obtaining such relief. He is very frequently instructed in injunction applications to enforce garden leave or post-termination restrictions against dealing, solicitation and poaching of employees, including non-compete provisions and to prevent breaches of confidence. Type of interim relief include injunctions, search orders, disclosure orders, delivery up orders and preservation orders. He is experienced at working in a team with solicitors and IT forensic experts.
- Has substantial experience of obtaining or resisting complex orders to preserve and recover data, including computer imaging orders, and disclosure orders. He has substantial background and understanding of computing and IT technical matters, which place him uniquely to deal with issues concerning forensic IT investigations on interim injunction applications.
- Acting for a FT250 insurer (one of the world’s leading providers of insurance, reinsurance and employee benefits) in High Court, Queen’s Bench Division proceedings to obtain interim injunctive relief preventing a departing senior executive from joining a competitor based on enforcing the negative obligations in his contract of employment.
- Internal law of international organisations
Advising and appearing in claims by employees of the European Bank of Reconstruction and Development before its internal Administrative Tribunal, which is not subject to any external law and operates according to the principles of the institutional law of international organisations. Advising employees of another international organisation headquartered in London in relations to potential claims. The details of this work are private and confidential.
- LLP Law
He regularly acts and advised on disputes centred on deferred remuneration provisions or deferred consideration in LLP and shareholder agreements or in relation to the effect and operation of termination provisions.
- Acted for Europe’s third-biggest alternative asset management business (funds of USD 40 billion under management) in multifaceted claims arising out of removal of an investment manager as an LLP member and his claim for profit share under the LLP agreement. Related proceedings in relation to the licensing of knowhow and IP with a company previously operated by the investment manager.
- Frequently adviser partner of law firm LLPs in relation to their rights and obligations on termination of membership and related issues. The details of this work are private and confidential.
- Career
2014 Appointed Queen’s Counsel
1991 Called to the Bar (Middle Temple)
1987 Scientist at MOD, Admiralty Research Establishment, software coding in LISP on Symbolics Machines
- Education
1991 Inns of Court School of Law
1990 Postgraduate Diploma in Law, City University
1986 BA Hons (Oxon), Experimental Psychology