Thomas Declerck
Partner
Brussels

Thomas Declerck
Partner
Brussels
Contact details
Thomas specialises in white-collar crime, investigations and complex litigation, with a particular interest in cybersecurity.
Thomas has represented a broad range of high profile financial institutions, corporates and senior individuals on corporate and financial crime matters, including fraud, bribery and corruption, money laundering, market abuse, breaches of financial regulation and workplace misconduct. In addition to his extensive trial experience, Thomas regularly assists clients in implementing effective compliance programmes and conducting internal investigations. Thomas also has a long-standing practice in international sanctions and export controls, both stand-alone and in the context of M&A.
Thomas co-heads our Belgian cybersecurity practice. In close collaboration with A&O’s cyber specialists globally, he uses his established litigation and crisis management skills to advise clients across the spectrum of prevention, incident response, and litigation (whether civil or criminal).
Thomas is admitted to both the Brussels Bar and New York Bar.
Expertise
Practices
Investigations, Enforcement and Business Crime
Sanctions, International Trade and Investment Compliance
Sectors
Qualifications
Professional
Admitted to the Brussels Bar, Belgium, 2011
Admitted to the Bar of the State of New York, USA, 2012
Academic
Master of Laws, Katholieke Universiteit Leuven (KUL) - Summa cum laude, 2010
LLM in International Legal Studies, New York University (NYU) - BAEF Francqui Foundation Fellow, Honorary Fulbright Scholar and Dean’s Graduate Award, 2011
Certificate Undergraduate Legal Studies (Erasmus Programme), King's College London, 2009
Experience highlights
Premier league football club KV Mechelen in disciplinary, criminal and civil proceedings in Belgium and Switzerland relating to allegations of match fixing, bribery and money laundering.
Advising a global wealth solutions provider as a defendant in highly publicised criminal proceedings surrounding the bankruptcy of Optima, a Belgian financial planner and bank.
Advising the private equity seller of a multinational over-the-counter consumer goods company in a EUR2bn CEPANI arbitration claim brought by the purchaser alleging fraud and various breaches of warranty in connection with the sale.
Advising a bank in relation to a CEO fraud involving deepfake technology causing major financial losses.
Related articles

Blog Post: 11 October 2023
On 3 October 2023, the European Commission announced a public consultation regarding the draft implementing regulation (Draft Regulation) establishing the European Common Criteria-based cybersecurity…
Blog Post: 30 August 2023
Webinar: Managing supply chain risk in the life sciences sector
Publications: 05 July 2023
Global sanctions on Russia accelerate focusing on sanctions circumvention and Russia responds

Expertise
Practices
Investigations, Enforcement and Business Crime
Sanctions, International Trade and Investment Compliance
Sectors
Qualifications
Professional
Admitted to the Brussels Bar, Belgium, 2011
Admitted to the Bar of the State of New York, USA, 2012
Academic
Master of Laws, Katholieke Universiteit Leuven (KUL) - Summa cum laude, 2010
LLM in International Legal Studies, New York University (NYU) - BAEF Francqui Foundation Fellow, Honorary Fulbright Scholar and Dean’s Graduate Award, 2011
Certificate Undergraduate Legal Studies (Erasmus Programme), King's College London, 2009
Pro bono
- Advising a global non-governmental organisation focusing on supporting children without parental care and families at risk in relation to a broad range of regulatory risk.
Other noteworthy experience
Advising:
- A listed Belgian telecom operator in multiple litigation proceedings challenging a planned EUR 2 billion investment in the roll-out of a new fiber-to-the-home network in Flanders and parts of Brussels
- The former risk officer of Fortis Bank in criminal and civil proceedings initiated in the wake of the sub-prime crisis and Fortis’ take-over of ABN Amro in 2007-2008
- A major financial services provider in responding to and mitigating various cyber incidents
- A broad range of financial institutions, financial service providers and multinational corporates on navigating the ever more complex EU, UK and US sanctions landscape
- An online gaming company in response to a distributed denial-of-service (DDoS) attack on its website servers
- An energy storage company in response to a major ransomware attack severely disrupting its operations across Europe
Recognition
Thomas Declerck is very analytical and strategic and will consider the matter from all possible angles
Legal 500, 2023
Rising Star
Legal 500, 2023
Up and Coming
Chambers Europe, 2023