Imagine a factory that pollutes the air. If government closes it down, can the operator allege undue encroachment on his property? If government remains inactive, can the neighboring farmer demand that his/her property must be protected? The two questions point to two dimensions of interrelation between environmental concerns and property interests. Property is either used as a barrier to or as a quest for environmental protection. This book examines how the weighing up of property and environmental protection interests is determined by law. It discusses solutions found in EU Member States and the EU looking both at regulatory and constitutional law. It is based on national reports guided by a common list of questions. Cross-cutting contributions highlight commonalities and differences with a view to develop a European ius commune. This is framed by analyses of the pertinent jurisdiction of the European Court of Human Rights, of the Court of Justice of the EU, and of Investor-State Arbitration.