Australian law blogger Kevin Jon Heller got his PhD in Leiden and describes the process of defending his thesis in a recent posting:
My casual attitude didn’t last long — only until I began to put on my tuxedo, complete with tails, in the room in which candidates change. My interlocutors for the viva, kindly known as ‘the opposition committee’, were changing on the other side of the room. The solemnity of the occasion finally penetrated my thick skull — this was my rite de passage into an academic tradition that had been taking place in Europe for centuries.
Once I had changed, Leiden’s pedel (registrar) explained the viva process to me and my two paranymphs, Mirjam and Bianca. The role of the paranymphs is now purely ceremonial; they sit and stand beside you during the viva. Traditionally, however, they served as the candidate’s protectors, intervening on his behalf if the opposition committee was being unfair or physically abusive (!).
The defense traditionally takes place in the Senaatskamer (Senate Room, 1733) which is adorned with portraits of the professors of the early days of the university and seats 64.