Coastlines have long attracted industrial activities, services, housing, and tourism. At select geographic locations, harbors host port facilities and provide local economic growth opportunities. As such, these areas also concentrate populations around the world. In the north of France, where the unemployment rate is high, port industries are still massive providers of work. However, in the last decades, the port development has become a major threat to the architectural heritage, the historical scenery, and the unique biodiversity of these areas, both at sea and on land. The impact of urban redevelopment has been clearly visible since 1950. At this point, this paper raises the following question: How is it possible, in this context, to efficiently limit this urban sprawl through legal frameworks to protect land, sea, and their in-between environment, in spite of the economic interests? The urbanization of the northern coastline of France has gradually expanded since 1950 until a fundamental act appeared in 1986, the Shoreline Act “Loi Littoral”. This act allows us to analyze the last thirty years of urbanization and its binding force towards the protection of the environment; and yet, we also understand that it has a limited role. It does not forbid all kinds of construction, but just new buildings coming out of nowhere, though expansion in urbanized areas is allowed. After decades of existence, this framework has been integrated by both politicians and citizens, and its results have been judged. If the law is now seen as a guardian of the shore, inhabitants and environmental organizations have often criticized its dimness, which favors interpretation. This paper analyzes the soft limitations that have affected the ongoing space consumption since the 1950s using aerial pictures provided by the IGN (Institut National de l’Information Géographique et Forestière), as well as if the rules were efficient enough in their protection.@en