Major changes to natural environments are related to the construction and the use of roads. Thus, in France, despite legal commitments, each year natural areas are disrupted. Forty-three legal instruments of natural areas protection and environmental assessments have been identified and classified according to the hierarchy of rules applicable under French law. A comprehensive and detailed hierarchical classification of these national, European and international instruments is presented. It sheds lights on the complex structure of the whole system, often contradictory or redundant. The effectiveness of the whole legal framework in protecting natural areas relative to road projects is analyzed on the basis of official legal texts and case law. The Natura 2000 network appears to be the most effective and relevant instrument. However, its applicability is limited in light of the EU requirements. National instruments are generally legally ineffectual. Among the natural areas, forest is the best protected by binding instruments. Despite the effectiveness of the protection offered by few instruments, overall they have failed to stem the loss of biodiversity. Introducing the concept of green and blue networks – thus connection – the Grenelle law II could compensate today shortcomings of conservation, provided it based on coercive obligations. Environmental assessment instruments – including EIA – show a disappointing reach toward actual protection and they occur relatively late in the decision process of projects. Establishing nature sanctuaries and enforcing existing instruments are necessary short term means of improvement of protection. However, introducing binding green and blue networks and ecosystem functioning into environmental assessments would be a way to sustainably improve the system of legal instruments.
