Referring to the Italian context, where unauthorized building is a quite common phenomenon, this article critically interrogates the relationship between planning rules and transgressions. Particularly, I focus on rules as defined by urban plans on the one hand and housing and planning 'abuso' – literally infringement – on the other. The way this term is used in Italian urbanism is the issue that inspired the research leading to this article. Indeed, 'abusivismvo' refers very generally to any sort of non-compliance with urban regulations. And yet, what kind of practices are supposed to transgress what kind of rules and what consequences follow? Drawing on Conte’s concept of nomotropism, I show that there is a (at least) twofold relationship between these two dimensions, including the transgressions 'in light of' the law and the rules 'following from' the transgression. By taking nomotropism seriously, it is finally possible to formulate a modest, responsible planning approach to transgressions.