Mr. Fonseca Morillo was, from 1986 to 1988, Administrator to the Directorate-General for Budgets (XIX-U-2), and from 1988 to 1989, Principal administrator to the Secretariat General of the Council (DG II, Economic and Financial Affairs). From 1989 to 1992, he was Assistant to the Director-General of the Commission's Forward Studies Unit. From 1992 to 1995, he was Advisor to the Director-General of the Forward Studies Unit, and, from 1995 to 1997, Advisor to the 1996 Intergovernmental Conference task force reporting directly to Commissioner Marcelino Oreja, responsible for the preparation within the Commission of the EU Treaty Review Conference. From 1997 to 1999, he was Advisor to the Secretary-General of the European Commission in charge of the Amsterdam Treaty monitoring unit. Between 1999 to 2004, he was Deputy Head of Cabinet and Head of Cabinet of Commissioner António Vitorino, responsible for Justice and Home Affairs.