I. Introduction
Creating a single European market has been on the agenda of policy makers essentially since nearly a quarter of a century starting with the Single European Act of 1987. A long struggle between interest groups deferred an application of the Act to natural gas by 10 years with the first Gas Directive coming into force. With no progress in achieving the foreseen goal, the creation of a competitive internal market for natural gas, a second and third Directive followed in 2003 (2003/55/EC) and 2009 (2009/73/EC). At the heart of the project and key to the natural gas industry is the free flow of molecules in a European system of transmission pipelines. This includes third-party access to the system as well as a costreflective and non-discriminatory tarification system that ensures a secure level of flows and provides sufficient investment incentives. This all plays against a highly regulated industry with oversight from a national and from this year onwards a European regulatory authority. Albeit the industry is technically less complicated than its sibling electricity the issue is equally complex.