1. If an Autonomous Community does not fulfil the obligations imposed upon it by the Constitution or other laws, or acts in a way seriously prejudicing the general interests of Spain, the Government, after lodging a complaint with the President of the Autonomous Community and failing to receive satisfaction therefore, may, following approval granted by an absolute majority of the Senate, take the measures necessary in order to compel the latter forcibly to meet said obligations, or in order to protect the above-mentioned general interests.
2. With a view to implementing the measures provided in the foregoing clause, the Government may issue instructions to all the authorities of the Autonomous Communities.
On October 27, the Catalonian parliament voted in favour of proclaiming independence. On the same day, the Spanish Senate approved the introduction of exceptional measures concerning Catalan autonomy. Thus, for the first time since the adoption of the Constitution in 1978, article 155 was used.
Prime Minister Mariano Rajoy's government adopted five decrees stating the autonomous authorities of Catalonia were recalled and their competences were delegated to the relevant Spanish ministers. Catalonian parliament was dissolved and the early elections in Catalonia were scheduled for 21 December 2017.
Posters against art. 155