EU law has had significant impacts upon the national law of its Member States. Much of this has been direct and by design; other influences have been subtler and more indirect in nature. To come to a fuller understanding of the extent of the impact of EU law, this range of impacts needs to be more carefully studied and organised. This exercise has both descriptive and potentially predictive elements: appreciating the former may help us to project the likely future implications of EU law developments, both legislative and judicial.