The reduction of land use has long been one of the central concerns of German environmental and land utilisation policy. Particularly since the German government's Sustainable Develop­ment Strategies set the goal of reducing the use of undeveloped land for settlement and trans­port purposes to a maximum of 30 hectares per day, quantitative approaches to realising this goal have been discussed. In this respect, particular hopes are placed in spatial planning and its instruments. Following the demand for the land-saving target to be enshrined in law, which was raised in the course of the most recent amendment to the Spatial Planning Act, this article discusses the central legal issues of such a regulation and its implementation in spatial planning.