“…7 Various other reasons have been put forward in the literature on ironclad patents to explain the use of royalties, including risk aversion (Bousquet et al, 1998), asymmetry of information (Gallini and Wright, 1990;Macho-Stadler and Pérez-Castrillo, 1991;Beggs, 1992;Sen 2005a), moral hazard (Macho-Stadler et al, 1996;Choi, 2001), product di¤erentiation (Muto, 1993;Wang and Yang, 1999;Caballero-Sanz et al, 2002;Poddar and Sinha, 2004;Stamatopoulos and Tauman, 2007), strategic delegation (Saracho, 2002), integer nature of the number of licensees (Sen, 2005b), variation in the quality of innovation (Rockett, 1990). 8 In Farrell and Shapiro (2008) and Encaoua and Lefouili (2009), the licensor is assumed to o¤er two-part tari¤ licensing contracts.…”