atastrophic or irreversible harms. This approach is more than just a question of which side bears the burden of proof (cf. Wu 2004). Instead, it represents a true middle course that allows policy makers to avoid having to foreclose any particular alternative when confronted with a policy choice that is ambiguous. Recast in this manner, the key regulatory question is whether the restrictions criticized by network neutrality proponents are SO pernicious and unjustifiable that experimentation should not be permitted. An analysis of the economics of the Internet reveals the existence of a number of plausible arguments demonstrating that deviations from network neutrality might well enhance economic welfare. The key to understanding why this might be the case is recognizing the fact that the Internet is subject to congestion. When networks are subject to congestion, one customer's usage of the network can degrade the quality of service that other The Regulation of Broadband Networks and the Internet customers receive. The primary finding of the literature on the economics of con- gestion is that competitive markets will reach an efficient equilibrium if each user is charged a usage-sensitive price set equal to his or her marginal contribution to congestion (see, e.g., Berglas 1976). As a result, some commentators have argued in favor of shifting all Internet services to usage-sensitive pricing (MacKie-Mason and Varian 1995a; Sidak and Spulber 1998; Wu 2003). At the same time, flat-fee pricing has persisted for a wide range of other congestible resources, such as ski lifts and local telephone service. The persistence of these practices has led to the creation of a literature exploring the circumstances under which usage-sensitive pricing might prove uneconomic. The general thrust of this literature is that transaction costs associated with a usage-sensitive pricing system can consume all of the economic benefits associated with a shift to usage-based pricing. When that is the case, eco- nomic welfare would be better se