Held several academic positions, namely as President of the Directive Council (1989-1991) and as President of the Scientific Council (1998-2001) of the Lisbon University School of Law. In the graduation course he has taught or is teaching the disciplines Theory of Law, Rights in rem, Law of Obligations, Introduction to the Study of Law, General Theory of Civil Law, Philosophy of Law, Law of Economics, Labor Law, Banking Law and Commercial Law.

Author of more than three hundred publications. Among these works stand out Da boa fé (1984, seven reprints), Tratado de Direito Civil (11 volumes), Direito do trabalho, Direito Bancário, Direito Comercial, Direito das Sociedades, Direito dos Seguros and Tratado da Arbitragem. Director of Revista de Direito das Sociedades and of Revista de Direito Civil, Deputy Director of Revista O Direito and member of the Editing Committee of Revista da Ordem dos Advogados, of which he was Deputy Director from 1990 to 2010.

Legal consultant, national and international arbitrator and lawyer, being a founding member of the law firm António Menezes Cordeiro & Associados. President of CIDP and IDP. Effective partner of the Lisbon Academy of Sciences (Academia das Ciências de Lisboa). President of the Arbitration Centre of the Portuguese Chamber of Commerce and Industry (since 2016).

He has also lectured as a Professor of Law at the Guinea-Bissau Law School. He was Visiting Professor at Georgetown University, Washington D.C., USA. He wrote several juridical papers and books published in Portugal and Brazil. He also co-founded the Labor Institute of Law, the Consumer Institute of Law, both part of the University of Lisbon, and the Portuguese Speaking Countries Jurists Community. He is currently member of the board of the Labor Institute of Law.

Guilherme was Head of the Portuguese Prime Minister´s Office during the XVIII Government (2009-2011) and Head of the Cabinet of the Minister for Public Works, Transport and Communications of the XVII Government of Portugal (2005-2009). He participated in several official and bilateral meetings in several countries of Europe, South America, Africa and Asia. During the Portuguese Presidency of the EU (2nd semester of 2007), Guilherme assisted the directorship of the Transport and Telecommunications Council.

Guilherme is currently a Partner at the Law Firm Macedo Vitorino & Associados.

Member of the FDUL Private Law Research Center.

Member of the Portuguese Institute of Civil Procedure.

Teaching: Introduction to the Study of Law, Law of Obligations, Labour Law, Contract Law and Insurance Law. He served as President of the Scientific Council of the Faculty of Law of the University of Lisbon (2006/2012).

Director of the Faculty of Law of the University of Lisbon (2015/2019).

Director of the Law and Social Studies Magazine (“Revista de Direito e Estudos Sociais”) since 2000.

Corresponding member of the Lisbon Science Academy.

Participation in legislative work: At the request of the Ministry of Social Security and Labour, coordinated the commission that prepared the draft Labour Code, between May 2002 and July 2003.

At the request of the Ministry of Finance and Public Administration, coordinated the commission that prepared the draft legal regime for the insurance contract, which came into force on January 1, 2009.

He held several academic functions, namely member of the Assembly of Representatives (1998/2002), the Pedagogical Council (1999/2002), the Directive Council (2001/2002), the Scientific Council (2015/2017), and is currently a member of the School Board (2018/2019) of the Faculty of Law of the University of Lisbon.

Regular speaker at conferences and postgraduate courses, namely at the Faculty of Law of the University of Lisbon, the Catholic University of Portugal (Oporto) and the New University, as well as the Labour Law Institute (IDT), the Private Law Research Center of the Faculty of Law of the University of Lisbon (CIDP), the National Labor Law Congresses; he is also the executive coordinator of the post-graduate course at IDT. He is the author of several dozen books and articles, especially in the area of ​​Labour Law.

Since 2015, he has been a member of the Scientific Committee for Collective Bargaining at the Labour Relations Center.

Deputy Director of Revista Jurídica Luso-Brasileira (CIDP), since 2015.

Lawyer and Consultant at Abreu Advogados (since 2013).

Member of the list of presiding arbitrators of the Economic and Social Council (since 2012).

He participated in the elaboration of several diplomas, especially the one related to the Labour Code of 2003 and the respective complementary legislation, having, as Advisor to the Secretary of State for Labour of the XV Constitutional Government, accompanied the negotiation of these and other diplomas, in the Permanent Commission for Social Consultation.

Participates regularly in conferences and postgraduate courses in the areas of Labour Law and Consumer Law.

She is a writer for Revista Jurídica Luso-Brasileira, a publication of the Private Law Research Center of the Faculty of Law of the University of Lisbon.

Former Lecturer at the Faculty of Law of the University of Lisbon in the subjects of Labour Law I and II, Law of Obligations I and II, Property Law and Maritime Law. Former Lecturer at the Faculty of Law of Bissau, under the Cooperation Protocol agreed between the Faculty of Law of the University of Lisbon and the Portuguese Institute for Development Support, where she coordinated Introduction to the Study of Law, General Theory of Civil Law, Law of Obligations, Special Contract Law and Private Law (Warranties).

Former Expert Advisor to the Secretary of State for Employment, at the Ministry of Economy and Employment.

Carried out consultancies for various entities, highlighting the work carried out for UNDP – United Nations Development Program, IPAD – Portuguese Institute for Development Support and the Government of Guinea-Bissau and the World Bank.

Since January 2018 preparing doctoral thesis on the theme of “The impossibility of the maintenance of the employment relationship in the dismissal with just cause”.

Lawyer since 2014, mainly in the areas of Labour Law and Civil Law. Since 2018, member of the Employment group of DLA Piper ABBC.

He taught at this Faculty, among other subjects, General Theory of Civil Law, Law of Obligations, Comparative Law, Private International Law, International Commercial Law, Copyright and Industrial Property Law. He was Vice-President of the Board of Directors of the Faculty of Law and is President of its Institute for Legal Cooperation.

Lawyer in Lisbon since 1987. He participated as an arbitrator, lawyer and jurist in more than eighty national and international arbitrations.

He is President of the Portuguese Association of Intellectual Law and Member of the Board of the Portuguese Arbitration Association. Associate Member of the International Academy of Comparative Law and the Hispano-Portuguese-American Institute of International Law.

Main scientific publications: International commercial arbitration: Law applicable to the merits of the case (1990); Pre-contractual liability in Private International Law (2001); Private International Law: Essays (3 vols., 2002-2010); International protection of intellectual property (2008); La propriété intellectuelle en droit international privé (2009); Comparative Law (vol. I, 4th ed., 2018; vol. II, 2017).

Founding member of the Portuguese Labour Law Association (APODIT) and the Labour Law Institute (IDT), member of the FDUL Private Law Research Center (CIDP), of the Comunidad para la Investigación y el Estudio Laboral y Ocupacional (CIELO) and the International Association on Workplace Bullying & Harassment (IAWBH).

Lecturer in Postgraduate courses and in intensive courses on Labour Law, Social Security Law, Business Law, Insurance Law, and Data Protection and lecturer in Portugal and abroad.

Lawyer, with registration in the Bar Association suspended by option.

Responsible for the legal and labour advisory department in a large private sector company.

Author of several publications on labour law (until 2007 under the previous professional name, Isabel Ribeiro Parreira).

Lecturer of the Faculty of Law of the University of Lisbon between 1988 and 2001 and the Higher Institute of Social and Political Sciences of the Technical University of Lisbon between 2003 and 2006.

He teaches several Postgraduate courses in Labour and Social Security Law, organized by the Faculty of Law of the University of Lisbon, the Faculty of Law of the New University of Lisbon, the Catholic Faculty of Law – Oporto’s School and the Higher Institute of Languages and Administration (ISLA).