2017–2018 Spanish constitutional crisis

A constitutional crisis took place in Spain from 2017 to 2018 as the result of a political conflict between the Government of Spain and the Generalitat de Catalunya under the then-President Carles Puigdemont—the government of the autonomous community of Catalonia until 28 October 2017—over the issue of Catalan independence. It started after the law intending to allow the 2017 Catalan independence referendum was denounced by the Spanish government under Prime Minister Mariano Rajoy and subsequently suspended by the Constitutional Court until it ruled on the issue. Some international media outlets have described the events as "one of the worst political crises in modern Spanish history".

Puigdemont's government announced that neither central Spanish authorities nor the courts would halt their plans and that it intended to hold the vote anyway, sparking a legal backlash that quickly spread from the Spanish and Catalan governments to Catalan municipalities—as local mayors were urged by the Generalitat to provide logistical support and help for the electoral process to be carried out—as well as to the Constitutional Court, the High Court of Justice of Catalonia and state prosecutors. By 15 September, as pro-Catalan independence parties began their referendum campaigns, the Spanish government had launched an all-out legal offensive to thwart the upcoming vote, including threats of a financial takeover of much of the Catalan budget, police seizing pro-referendum posters, pamphlets and leaflets which had been regarded as illegal and criminal investigations ordered on the over 700 local mayors who had publicly agreed to help stage the referendum. Tensions between the two sides reached a critical point after Spanish police raided the Catalan government headquarters in Barcelona on 20 September, at the start of Operation Anubis, and arrested fourteen senior Catalan officials. This led to protests outside the Catalan economy department which saw Civil Guard officers trapped inside the building for hours and several vehicles vandalized. The referendum was eventually held, albeit without meeting minimum standards for elections and amid low turnout and a police crackdown ended with hundreds injured. Also Spanish Ministry of Internal Affairs reported that up to 431 officers were injured bruised or even bitten.

On 10 October, Puigdemont ambiguously declared and suspended independence during a speech in the Parliament of Catalonia, arguing his move was directed at entering talks with Spain. The Spanish government required Puigdemont to clarify whether he had declared independence or not, to which it received no clear answer. A further requirement was met with an implicit threat from the Generalitat that it would lift the suspension on the independence declaration if Spain "continued its repression", in response to the imprisonment of the leaders of pro-independence Catalan National Assembly (ANC) and Òmnium Cultural, accused of sedition by the National Court because of their involvement in the 20 September events. On 21 October, it was announced by Prime Minister Rajoy that Article 155 of the Spanish Constitution would be invoked, leading to direct rule over Catalonia by the Spanish government once approved by the Senate.

On 27 October, the Catalan parliament voted in a secret ballot to unilaterally declare independence from Spain, with most deputies of the opposition boycotting a vote considered illegal for violating the decisions of the Constitutional Court of Spain, as the lawyers of the Parliament of Catalonia warned. As a result, the government of Spain invoked the Constitution to remove the regional authorities and enforce direct rule the next day, with a regional election being subsequently called for 21 December 2017 to elect a new Parliament of Catalonia. Puigdemont and part of his cabinet fled to Belgium after being ousted, as the Spanish Attorney General pressed for charges of sedition, rebellion and misuse of public funds against them.