Article 120

The Regions may not levy import, export or transit duties between Regions, or adopt measures that in any way hinder the freedom of movement of persons or goods between Regions, or limit the right of citizens to work in any part of the national territory. The Government may exercise its powers of substitution in the case that organs of the Regions, Metropolitan Cities, Provinces and Municipalities fail to abide by international rules and treaties or European Union legislation, or in the case of grave danger for public safety and security, or whenever required in order to safeguard legal or economic unity and in particular the essential level of benefits relating to civil and social entitlements, irrespective of the territorial boundaries of local governments. The law shall determine such procedures as to ensure that the power of substitution is exercised in compliance with the principles of subsidiarity and loyal co-operation.