Professor of Constitutional Law at the Aristotle University of Thessaloniki. 

Member of the Greek Parliament (1993-2019)

 Minister for Press and Mass Media- Government Spokesman (1993-95),  Minister for Transport and Communications (1995-96), Minister for Justice (1996), Minister for Culture & Sports (1996 – 1999), Minister for Development, Energy, Industry, Trade, Tourism and Technology (1999-2000), Minister for Culture & Sports 2000-2004 (in charge of coordinating the entire range of aspects of the Athens 2004 Olympic Games preparation (Infrastructures, relations with International Olympic Committee etc.)

Minister for National Defence (2009-2011)

Deputy Prime Minister and Finance Minister (17.06.2011 – 18.03.2012)

President of PASOK (2012-2015 ) 

Deputy Prime Minister and Minister of Foreign Affairs (2013-2015)

General Rapporteur for the revision of the Greek Constitution (1995-2001) 

Rapporteur of the Parliamentary Assembly of the Council of Europe for the implementation of the judgments of the European Court of Human Rights (2017-2019).