Since 2012, the EPA Alzette-Belval has embedded the strategy developed by public actors from all levels to trigger development and regain strategic room for manoeuvre in the context of steady growth in Luxembourg. The 8 municipalities under scrutiny – the association of municipality “Pays Haut Val d’Alzette”, with 28,000 inhabitants – are marked by deindustrialisation and the attractiveness of Luxembourg’s economy, which overflows its national boundaries. The vast majority of the workforce is driven to Luxembourg, and pressure on public amenities is growing. The EPA is a state-led agency with the capacity to “take back” planning responsibilities from other administrative levels to plan specific areas. This instrument is unique in the French planning system as all levels remain involved in the governance structure and as the EPA brings technical expertise and financial resources to the locality. This case study scrutinises on how the EPA can represent a leverage for greater spatial justice within and beyond the locality, in the context of growing cross-border interdependencies. What does spatial justice mean in a cross-border context? How equitable can a cross-border area be? For a couple of years, a shared awareness of the locality’s needs has reached all levels of governance from the local to the national level. The dedicated instrument, the EPA, is equipped with the regulatory and financial capacity to act. It holds also legitimacy, know-how and expertise. It is well accepted by formal stakeholders in the locality and in the broader regional and cross-border context. The EPA appears as an appropriate tool to ensure development in a coordinated manner, considerate of sustainability, and limited use of agricultural land, thus avoiding urban sprawl and scattered urbanism. Yet, the EPA is challenged to find appropriates means to 1) inform the public of its activities; 2) develop a participatory approach when using the diverging opinions as a resource for implementing its projects. Its action partly overlooks ...