The purpose of regulation is to control private sector activity to limit the likelihood of market failure. There is much debate over the validity of such intervention,4 but the potential sources of market failure in relation to infrastructure include: the monopolistic tendencies of some service sectors, externalities causing the unintended capture of benefits, and the lack of information.5 The increasing role of the private sector in infrastructure and service-related activities now means governments are withdrawing from the role of provider but stepping up their role as a regulator.