Thomas Declerck


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 is co-head of Belgium cybersecurity. In close collaboration with the firm'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.


Representative matters

A global wealth solutions provider in highly publicised criminal proceedings surrounding the bankruptcy of Optima, a Belgian financial planner and bank.

A multinational construction group as a defendant in criminal trial involving claims of public bribery and forgery in the context of a multimillion dollar project in a foreign jurisdiction.

Liberty Global against claims by FourWorld Capital following Liberty Global’s acquisition offer for Telenet.

A bank in relation to a CEO fraud involving deepfake technology causing major financial losses.

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.

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.

Pro bono

Thomas provides pro bono advice to a range of not-for-profit organisations focused on supporting children and families at risk and transparency and accountability projects.
Thomas Declerck is very analytical and strategic and will consider the matter from all possible angles.
Legal 500, 2023
Rising Star.
Legal 500, 2023



Admitted to the Brussels Bar, Belgium, 2011
Admitted to the Bar of the State of New York, USA, 2012


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 
A&O Shearman was formed on May 1, 2024 by the combination of Shearman & Sterling LLP and Allen & Overy LLP and their respective affiliates (the legacy firms). Any matters referred to above may include matters undertaken by one or more of the legacy firms rather than A&O Shearman.