After a long period in the doldrums, in recent years the use of federalism to understand the European Union (EU) has undergone something of a renaissance. However, some of its core claims remain ambiguous and many have not been tested empirically. This paper argues that amongst a number of truth claims made by federal theorists, potentially the most illuminating is that relating to the allocation of decision-making powers (or tasks) across different levels of governance. In testing the value of what appears to be an increasingly distinct 'turn' in EU scholarship, it subjects this particular claim to empirical testing within the area of environmental governance - a policy area which is especially well suited to federal theory. Drawing on three relevant federal theories, this paper concludes that each one sheds new light on task allocation, but all have their blind spots, suggesting the need for further refinement, empirical testing and possibly synthesis with other theoretical approaches.