Within the on-going ecological transition, mobility systems are considered as sociotechnical systems that raise several challenges for local authorities due to the different levels of decision, a complex stakeholder network and the numerous objectives to be dealt with. Designers are therefore seeking to develop new frameworks to support local authorities moving towards more sustainable mobility systems. Based on the French context, this study relies on an analysis of the regulation and an interview-based survey that depict the mobility design from the local authorities’ perspective. First, it investigates the objectives defined in the law and the difficulties met by local authorities. Then, it highlights the main political, organisational, and knowledge barriers for sustainable mobility. Finally, it proposes a set of recommendations to create a framework to better define and prioritise the objectives, ensure efficient planning and monitoring, clarify the interactions between actors, and enhance mobility plans.