Eric-Jean mainly focuses on business law and advises both French and foreign clients, particularly investors and listed companies, in cases in relation to corporate, arbitration, energy (oil & gas), infrastructure and project finance.

With a significant legal expertise on an international law, he founded his first law-firm in Paris in 1983. In 1995, he co-founded in Hong Kong the law-firm named Thomas Mayer & Associés (TMA) specialized in the economic migration of companies from Europe to South-East Asia, particularly China, and from South-East Asia to Europe, regularly honored since then as a leading structure in this domain by the Hong Kong Business Outstanding Enterprise Award.

In 2010, he co-founded with Emma Bensoussan-Crémieux the Parisian firm Thomas, Mayer & Associés. They were joined in 2013 by Charlotte Callet. In 2020, the Firm is renamed Vespera in association with the renowned Hong Kong law firm Lily Fenn & Partners ((https://www.lilyfennlawyers.com/en/).