This paper introduces defection into the strategic R&D model. In defecting, a firm cheats by choosing its R&D expenditures to maximise its own profits, instead of maximising the joint profits of the cooperating firms. Two cooperative environments are considered: R&D cartelisation, where firms coordinate R&D activities; and RJV cartelisation, where firms coordinate R&D activities and share information. Under R&D cartelisation, defection entails an increase (decrease) in R&D and effective spillovers for low (high) spillovers; whereas under RJV cartelisation, defection always entails a decrease in R&D and effective spillovers. Under R&D cartelisation, consumer surplus and total welfare increase (decrease) with defection when spillovers are low (high). Whereas consumer surplus and welfare always decrease with defection under RJV cartelisation. Under R&D cartelisation, the incentives for defection first decrease then increase with spillovers; they also increase with the size of the market, but decline with production costs and R&D costs. Moreover, the incentives for defection are higher under RJV cartelisation. With low spillovers under RJV cartelisation, a firm prefers to be subject to defection by the other firm, to not cooperating at all. Punishment for defection is considered, under the form of abstaining from information sharing. Copyright Blackwell Publishing Ltd/ University of Adelaide and Flinders University 2006.
