Juan Iglesias Santos was born in Las Veguillas (Salamanca) in 1917. He earned his doctorate in Law from Salamanca's Universidad Pontificia, where he began teaching as assistant lecturer at the age of 18. He has been Professor of Roman Law at the Faculty of Law of Madrid's Complutense University since 1953, and is now its honorary dean. He has been researching and teaching intensely for almost sixty years, and has been a member of the Royal Academy of Jurisprudence and Legislation since 1980.

He has published widely on Roman Law, and his texts include 'Roman Law. History and Institutions', a basic tool for thousands of Spanish and Latin American undergraduates, 'Roman Law. The Institutions of Private Law' (1950), which received international acclaim, and 'The Spirit of Roman Law' (1980). He is also the author of more specialised texts, 'Historical-Legal Miniatures' being one of the most outstanding of them. His literary activity is not limited to this discipline and nothing else. Juan Iglesias Santos has published an autobiographical novel with the title 'Don Magin, teacher and martyr', as well as writing for publications like La Gaceta and ABC.

He is a permanent member of the Academy of Moral and Political Sciences of Naples, the honorary president of the Spanish Society of Roman Law, and a member of the Société Internacionale des Droits de l'Antiquité. The Cross of the Civil Order of Alfonso X el Sabio, in the category 'for merits in the field of teaching' figures amongst the honours he has received.