Nicolas de Sadeleer teaches environmental law at the Facultés universitaires Saint-Louis in Brussels, where he is Director of their Environmental Law Centre, CEDRE. He was awarded a PhD with distinction in 1998 by Saint-Louis for his work on the application of environmental law principles to positive law. An updated version of the thesis was published in November 1999 in Belgium and Paris (Les principes du pollueur-payeur, de prévention et de précaution, Brussels, Bruylant/ Paris, AUF, 1999, 437 pp.). He is a guest lecturer in Université catholique de Louvain.
He is also a member of the IUCN and sits on the board of Environment Law Network International.