Most recently, Zagklis attended the Leadership in Corporate Counsel programme at the Harvard Law School.

[3] Zagklis practiced next to the pioneer sports lawyers Pantelis Dedes in Greece from 2004 to 2008, and next to Dirk-Rainer Martens in Munich, Germany from 2008 to 2016.

At the time with Dede, he represented some of the top players such as Michalis Kakiouzis, Giorgos Sigalas, and Arvydas Macijauskas.

[3] Since 2008, Zagklis is in charge of the Basketball Arbitral Tribunal (BAT), he is an FIVB legal counsel, advising on a wide range of commercial and sporting legal issues, and has represented various clubs and players before FIFA, UEFA and acted as an assistant to the Court of Arbitration for Sport in three Olympic Games (2004, 2006, and 2008).

[3] Zagklis has published several articles on sports law, policy, labor relations, and arbitration.