In the late 1990s, when I completed my doctoral dissertation on treaty interpretation, I had the great pleasure of being supervised by Professor Aleksander Peczenik. Sadly, Aleksander is no longer with us, as he passed away in 2005, far too early, at the age of 67. I devote this book to his memory. Aleksander was a sharp and energetic mind. He was a scholar fully dedicated to his work, and a very kind and generous personality at that. For the rest of my academic life, he will remain a shining example of a true scholar.
I extend my sincerest gratitude also to those colleagues who at different occasions engaged with me in discussions of jus cogens issues. Among these colleagues, I thank especially Eduardo Gill-Pedro, Valentin Jeutner, Katie Johnston, Uta Bindreiter, Christian Dahlman, David Reidhav, Anna Nilsson, Charles Jalloh, Eric de Brabandere, Markus Gunneflo, Letizia Lo Giacco, Daria Davitti, Daniel Costelloe, Scarlet Wagner, Karol Nowak, Benedikt Pirker and Jennifer Smolka.