Learn about our History

About us

Three decades of excellence

Est. 1986

Theodossis Gatsos and Panagiotis Tsoumanis started their careers in the early ’80s. By the time the firm was formed, each of the founding partners had already achieved considerable professional prominence emanated from similar backgrounds but distinctive practicing skills and scientific interests. They decided to form Gatsos – Tsoumanis & Associates Law Firm by merging the law office of Theodossis Gatsos with the law office of Panagiotis Tsoumanis bringing together their long-established experience and knowledge of clients’ needs.

The emerged Law Firm has been dedicated to offering “tailor-made”, insightful and effective legal services to meet our clients’ advisory, litigation and transactional needs. We work diligently, providing clear and comprehensive legal support to meet the new digital, economic, environmental and political challenges our clients face. This includes finding the best solutions for our clients’ complex matters with the aim of providing appropriate advice and defending their litigation.

Our values and guiding principles

The three basic principles of advocacy

Many centuries have passed since Aristotle first presented the three basic principles of advocacy: Ethos, Pathos, Logos. The issue however remains timeless. In our fast changing world, how can lawyers efficiently defend their clients’ interests?

Οur Firm is focused to the diligent management of our clients’ legal matters within the framework of Aristotle’s everlasting principles.



Our “ethos” is reflected in our capacity to prove to our counterparts that we are a credible source, worth listening to our argumentation.



Our “pathos” refers to our deep interest for our practice. We are fascinated to work closely with our clients on solutions that will transform their businesses, markets and even sectors.



Our “logos” is our tool to convince by using legal weapons in the most efficient way to defend our position. Our reward is the sustainable success of our clients.

35 years of experience in Court Rooms

We are tenacious, trusted, effective professionals with a track record of delivering tailor-made solutions that exceed clients’ expectations. Our logical, rigorous way of working means we can manage large, complex projects as well as smaller concerns – all within tight timeframes.

360 Legal solutions

What we do best

Our business model is based not only on assisting clients with their investments in the market but also on getting to know their business and the sector in which they operate, in order to offer an effective service, tailored to their particular needs. This approach enables us to create solid, long-lasting client relationships.

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When and where it matters most. We help our clients take correct decisions and find innovative solutions to their complex challenges.