 requiring the creation of interfaces and metering systems at locations other than major nodes and by taking information about projected traffic flows outside the network. It also violates the Coasian theory of networks by externalizing functions that would more efficiently be provided by the network owner. By their very nature, market transactions for access are voluntary. They are motivated by gains from trade. Market transactions for access reflect the relative effects of market transaction costs and internal governance costs. Making access mandatory changes the terms of the transactions, including prices and product features. As a result, access-based public policy affects both the boundaries of individual networks and interactions among networks. Mandatory access is likely to change the costs of network governance. In addi- tion, mandatory access changes the transaction costs of market transactions. The resulting changes in the relative costs of network governance and market trans- actions will change the market equilibrium. Changes in costs and opportunities for arbitrage may be expected to impact all forms of access transactions: retail, wholesale, interconnection, platform, and unbundled. Such effects arise even if the regulations are confined to one type of access, such as unbundled access. The effects are extensive because they tend to alter the boundaries of networks and the pattern of interconnections between networks. For example, changing platform access under the banner of promoting network neutrality can be expected to alter the technology and configuration of networks and the pattern of interconnections. Public policy discussions have been framed in terms of "access to information," although what is meant is access to the net- works that transmit the information. Limiting a network firm's ability to control network utilization and to specify network protocols will have far-reaching effects on economic efficiency. Users of network services benefit when prices, products, and quality of service are 