Tanja Masson-Zwaan is Deputy Director of the International Institute of Air and Space Law at Leiden University. She has specialised in the field of air and space law for the past 25 years.

Masson-Zwaan currently teaches air and space law as part of an advanced Masters programme (LLM) in air and space law at Leiden University, and carries out various research. She is President of the International Institute of Space Law (IISL) and, over the years, has published papers on a variety of topics. She lectures on space law all over the world, advises the Dutch government and other national and international bodies on matters related to space law, and attends the sessions of the United Nations Committee on the Peaceful Uses of Outer Space as an observer.

After obtaining her Masters degree in international law, she was Co-Director of the International Institute of Air and Space Law (IIASL) at Leiden University between 1985 and 1990. She then spent almost 15 years abroad before returning to the Institute in 2008. During her expatriation, she set up and taught courses in air and space law at the National University of Singapore, worked as a consultant for industrial and institutional clients in France, and served many years as Executive Secretary of the IISL. She created Adastra Consulting after having moved back to The Netherlands in 2004 and worked as an independent consultant on various projects in the fields of air and space law.

Masson-Zwaan is a recipient of the Distinguished Service Award of the IISL (2001) and of the Social Sciences Award of the International Academy of Astronautics (IAA) (2008). She is a member of various professional organisations such as the International Astronautical Academy (IAA, full member), the Académie de l’Air et de l’Espace (ANAE, France), the International Law Association (ILA, including its Space Law Committee and the Netherlands’ Branch NVIR), and the European Centre for Space Law (ECSL), of which she was a board member between 1989 – 1996. She is a faculty member of the London Institute of Space Policy and Law, board member of Women in Aerospace-Europe (created in 2009) and the Netherlands Society for Aerospace (NVR); an advisory board member of HE Space Operations, the Space Generation Advisory Council (SGAC), and the Asian Journal of Air and Space Law (National University of Juridical Sciences, Kolkata, India).