The purpose of this paper is to assess the effectiveness of the planning tools offered by the legislature and to show that zoning decisions, which are used in spatial planning on a fre-quent basis, pose a threat to spatial order and sustainable development. The example of the city of Kostrzyn-on-Odra shows that the problem of suburbanization affects not only metropolises, but also smaller local govern-ment units. Through an analysis of the decisions issued in the city, the problem is presented overflow of development and the helplessness of the authority in the face of the regula-tions in force. An assessment was made of the adopted local plans and their importance in shaping public space. Consequently, the work confirms the thesis that the system regula-tions responsible for the correct formation of spatial policy are a significant problem in practice. Even the adoption of a local zoning plan does not guarantee that self-sustaining and aesthetically pleasing functional areas will be created.