The monitoring of activists by the police forces in Spain is far from being an anecdote. However, some cases deserve special mention because of their seriousness and their enormously damaging consequences for the right to privacy and the secrecy of communications. Surveillance through the interception of communications and the extraction of data from personal devices, such as mobile phones, tablets and computers has been particularly harsh against politically organized anarchism and Basque and Catalan pro-independence movements, although also union leaders and other political activists have been monitored in this way.

Between 2013 and 2015, 68 people were arrested in a series of macro-operations against anarchist groups. Some of the people arrested had been subjected for a long time, even for years, to particularly invasive and damaging police tapping, where most of the conversations presented as evidence in court were of an intimate nature or related to her affective and friendship networks. Another of the most recent cases of police wiretapping of political dissidents was the investigation against the so-called Committees in Defence of the Republic (CDR), Catalan pro-independence grassroots groups, which involved the placement of GPS devices on vehicles in order to to track their movements.