His practice stood out for his vast experience and expert knowledge in the maritime field, in the legal advice and the defence of the interests of vessel proprietors, shipowners or their liability insurers (P&I), companies in the energy sector. Particularly relevant was his work in several matters related to maritime risks, especially maritime pollution, taking on the legal representation, more often than not, of several claimants, conducting multiple judicial and administrative proceedings.

Likewise, he was a Member of the Panel of Arbitrators of the Arbitration and Mediation Centre of the Santiago Chamber of Commerce (CAM Santiago), Member of the Panel of Arbitrators of the Arbitration and Mediation Centre of the V Region and, on several occasions, he acted as an arbitrator appointed by mutual consent of the parties.

He was also member of the Hon. Court of Appeal of Valparaíso (2014-2017).

He not only exercised the legal profession in the private practice but, for many years in the beginning of his career, he also held public office, as Officer of Valparaíso Public Defender, Casablanca Public Defender, Head Lawyer at the Free Legal Advice Centre of the Valparaíso Bar Association in Casablanca and Head Lawyer at the Free Legal Advice Centre of the Curacaví Bar Association.

In the academic practice, he won the Luis Vicuña Suárez award for having graduated at the top of his Civil Law class, Faculty of Law, Universidad de Chile, Valparaíso, won two awards in Criminal Law from the Institute of Criminal Sciences. His dissertation, on non-material damage within the scope of the contractual liability, was subsequently published as ‘El Daño Moral en la Responsabilidad Contractual’ by Editorial Jurídica de Chile.

As a professor of Civil Law and Maritime Law at the Faculty of Law, Universidad de Valparaíso, he had a solid and fruitful teaching career for almost fifty years, excelling in the university work. In 2015 he was given the title of Emeritus Professor in recognition of his significant contribution and development of said subject-matters and for his support to the progress of the Faculty of Law.

Together with this, he was the creator and director of the Commercial and Maritime Law Yearbook of the Faculty of Law, Universidad de Valparaíso.
He also stood out in the academic administration holding the positions of Director of the Faculty of Law, Academic Secretary and Secretary of the Faculty of Law, the latter position held for more than 10 years.

Professor Tomasello left his mark in dozens of generations of lawyers; nonetheless, with his prolific scientific production, in the teaching field and in the practice, first related to the civil law and then to the maritime law, he gained recognition as one of the most prominent voices in several issues within the wide range of the private law.

In 2018, he was distinguished with the Premio de Excelencia en el Ejercicio de la Abogacía [Legal Practice Excellence Award] by the Valparaíso Bar Association.