Accustomed to high-profile cases, Mathias assists companies, executives and public figures in prominent criminal cases. He handles a wide range of criminal issues, including ethical conduct offences, white collar law, labour law, health and safety offences, and environmental criminal law.

Through his expertise in media law, Mathias specialises in protecting the reputation and image of businesses and individuals. He regularly appears before specialised courts where he represents both media outlets and individuals in matters pertaining to defamation, invasion of privacy, and the presumption of innocence.

Mathias places this dual expertise at the service of his clients, advising them on legal and reputational risk prevention, in the context of internal investigations and compliance requirements (Sapin 2 , duty of care, inspections by the French Anti-Corruption Agency).

According to Legal 500, Mathias Chichportich has an outstanding strategic vision and a contemporary approach to his profession. He harnesses his immense talent, tenacity, and extensive experience to serve his clients effectively. Mathias has rare qualities as a litigator: he translates complex and sophisticated strategies into a clear, direct language for maximum effectiveness.

In 2018, he co-authored Mortelle transparence (Albin Michel), an essay on the adverse effects of the digital age on society, with Denis Olivennes.

He has taught criminal procedure and crisis communications in two degree programmes at the Paris-Panthéon-Assas University (Data Officer and Compliance Officers), as well as a class on criminal law in public procurement at Paris 1 Panthéon-Sorbonne University (Master 2 in Public Business Law).