The Convention Concerning the Exchange of Greek and Turkish Populations is signed at Lausanne, Switzerland on the 30th January, 1923 by the Governments of Greece and Turkey.  Papapolitis & Papapolitis is appointed as the legal advisor to the Greek Government for the exchange of property between approximately two million residents of both countries.

Nicholas Papapolitis Sr. joins the Firm after completing his post-graduate studies at Hubolt University Berlin, Sorbonne Paris II, Cambridge and Columbia Law School. In 1946, he moves to New York as a partner of a major New York law firm and is invited to head up their shipping practice after winning a landmark shipping litigation in the New York State Court.

Savvas Papapolitis, the eldest son of John Papapolitis Sr., who had joined the Firm in 1935, is elected as a Member of the Greek Parliament and begins a bright political career during which he is the youngest elected leader of the leading opposition party (EPEK), co-founds the Centre Union Party and is appointed Minister of Trade and Minister of Industry. Professor Nicholas Papapolitis Sr. returns to Greece and rejoins the Firm. He acts as the legal advisor to the Prime Minister of Greece, Nikolaos Plastiras and is elected Lecturer in Commercial Law at the Law Faculty of the University of Athens and Professor of Commercial Law and Shipping Law in the Law Faculty of the Aristotle University of Thessaloniki.

By the early 1960s, Papapolitis & Papapolitis has become one of the largest and most preeminent firms in Greece, with a corporate culture and work ethic modelled on those adopted by the US firms, which proved highly innovative in the Greek market. The Firm counts major shipping companies and corporations among its clients and gains a reputation for the “Papapolitis School of Thought”. The regime of the Colonels takes power in Greece and Papapolitis & Papapolitis acts in the landmark case for the Judges of the Supreme Court of Greece.