The fourth annual Alumni Seminar was held at the International Tax Center of the University of Leiden, the Netherlands, on 28 August 2008. The Seminar addressed recent case law on the interpretation and application of tax treaties. The panellists were Séverine Baranger (alumna 2006/07), Wolfgang Oepen (alumnus 2002/03) and Michael Kandev (alumnus 2005/06). The panel was chaired by Raffaele Russo (alumnus 2001/02). The proceedings of the Seminar are summarized in this note.