Spanish police spied on the headquarters of pro-independence Catalan party CUP on 20th September 2017 without an order from any judge or from prosecutors and seized referendum campaign materials from cars outside.
Today, a year later, the police report on the operation has been released.
The same day that the Civil Guard were searching the economy ministry and various other Catalan government offices, and that they arrested 14 senior officials, the great majority from ERC and involved in organising the referendum, the Spanish National Police were outside CUP's headquarters. The spontaneous calls for protests that day would see demonstrators gather around the building to prevent police from entering with peaceful resistance.
The police decided to throw together an operation, without specific legal permission, to increase the pressure on the upcoming referendum.
They seized posters for the vote and other materials unrelated to it, like posters and stickers for a campaign to bring water back under public ownership, volunteer bibs and hats reading "yes, to live means to take sides". They also took away a large proportion of the material for the 'yes' campaign CUP had, including posters, placards and banners.
All without authorisation.
The report admits there was no explicit permission, rather the police seized on prosecutors' instructions from 8th September saying they have to investigate the "illegal referendum".
On 20th September it spied on them. The result was images of CUP activists and collaborators taking campaign material into the building.
The surveillance started at 8am. Throughout the report, the police describe in all manner of detail the movements of various people entering and leaving the building, describing one of them as "looking expectant". They even remark that they give a poster to a tourist "who happened to be passing by".
Three cars arrive, one-by-one, between 12:30 and 1pm and the police check their files to see who they belong to. They start loading all three with referendum materials.
The police decide to act, stopping the cars and confiscating the referendum material from two of the cars and on the pavement. Given the immediate arrival of CUP members and supporters, "in order to avoid a serious disturbance to public order", they were unable to seize the material from the third car and decided to withdraw the officers who had been posted outside the building.
That said, it took until 8pm to make this decision to leave, after seven hours of visible presence outside the building and around 12 hours total when the surveillance is included. The spontaneous protest broke up around an hour later at 9pm.