In April 2004, Directive 2004/35 was promulgated establishing a framework for environmental liability based on the polluter-pays principle, with a view to preventing and remedying environmental damage. The Directive is the result of a long discussion on the usefulness of civil liability as a means for allocating the responsibility of environmental costs, on the various options to be taken into consideration, and on the various legislative systems that were analysed in order to have a comparative law perspective. After more than ten years of its coming into force, its history and its evolution need to be considered taking the various initiatives introduced at EU level into account, as well as the different national legal backgrounds in which it has been implemented. The comparative law analysis carried out in the chapter shows that significant divergent solutions exist at the national level. As a consequence, it is concluded that harmonization is still to be achieved in this area of environmental law.