Professor Marchesi has always combined teaching and academic research with expert advice and pro-bono work for International organizations. He has been teaching courses on International Law and International Human Rights in AUR since 2016. He also teaches in the Law Department of the University of Teramo and in the Master's programs of the Italian Society for International Organization (SIOI). For several years he has taught in the Faculty of Philosophy of the University of Rome “La Sapienza.”
Professor Marchesi was Chairperson of Amnesty International Italy from 1990 to 1994 and from 2013 to 2019. He has been a staff member and consultant, as well as a research delegate, trial observer, and member of delegations to international conferences on behalf of the International Secretariat of Amnesty International. He has also worked as a consultant for the Council of Europe, the European Parliament, and the European Commission, as well as for Italian public bodies and national and international NGOs.
Since 2017, Professor Marchesi has been the human rights expert for the National Guarantor of the Rights of Persons Deprived of their Personal Liberty (the Italian “National Preventive Mechanism” – NPM, under the United Nations Optional Protocol for the Prevention of Torture - OPCAT). He contributes to dailies and periodicals and is the author of over fifty academic articles and several books. His areas of interest include state responsibility, international human rights protection, international criminal justice, and refugee law.