This article provides an overview of the current EU regulatory framework for railway passenger and freight transport services, which came into force in late 2012 and has to be implemented at the national level by mid-2015. It also examines additional proposals for further review of this framework which were tabled by the Commission in early 2013 and are currently caught in the legislative process. The author assesses the contribution of these instruments to the effective market opening of the former State monopolies, which is one of the main objectives behind the reform efforts. Market opening is also being pursued through antitrust law enforcement both at EU and national levels, which is examined here as well, notably with regard to its ability to complement the legislative regulatory framework. On this dual basis, the article gives an analysis of the relationship between ex ante and ex post intervention in the railway sector. Building on a comparison with other network industries, this yields interesting conclusions with regard to the ongoing legislative debate and to the positioning of the companies active in the railway sector.