Ten Dutch municipalities have been fined by the Dutch Data Protection Authority (AP) because they secretly had their Islamic community investigated. Veenendaal, Delft, Ede and Eindhoven, among others, had a private research agency collect sensitive information, such as religion and family connections, about their residents. According to the supervisor, the municipalities acknowledge “that they have violated the law.”
It concerns a violation of the General Data Protection Regulation (GDPR) and it results in a fine of 25,000 euros each for the municipalities – a total of 250,000 euros. Some municipalities have subsequently also shared the collected sensitive information with the police, the terrorism coordinator NCTV and the Ministry of Social Affairs and Employment. “The privacy of the affected people has been seriously violated,” says AP chairman Aleid Wolfsen. “That has damaged confidence in many municipalities.”
An agency was hired to investigate like a private police force and draw up detailed reports on people
Revealed in October 2021 NRC the existence of years of investigations by municipalities in and into mosques. The studies took place between 2017 and 2021, in a period after Dutch young people left for Syria to fight there and Europe was hit by terrorist attacks. Wolfsen calls it “comprehensible” that municipalities at the time “wanted to map out what the Islamic structure in that municipality looks like.” Where it went wrong, he says, “is that an agency was hired to investigate like a private police, and drew up detailed reports on people. If you start doing that, there is a serious violation of their private lives.”
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The mosque reports that the AP has seen contain “all kinds of personal information” about Muslims who are active in municipalities, Wolfsen says. “Their contacts, networks, and an appreciation of their religious beliefs – how radical they are judged to be. Sometimes with photos.”
Secretly
The private researchers posed as visitors during the investigations at Islamic institutions, NRC previously revealed. The AP has not been able to determine that there was “infiltration,” says Wolfsen. “Infiltrating means that you really assume another identity, a cover. We have not encountered that. What we see is that people were followed, that inquiries were made about them, without their knowledge. The researchers were secretly watching, they did not identify themselves.”
That was enough for the AP to draw conclusions. “We could do much more research, but because all municipalities themselves already admitted that these investigations were unlawful, we thought it better to reach a settlement together and settle it this way.”
Immediately after the publication in NRC, most municipalities still denied the existence or the scope and methods of the studies. Some mayors later apologized to residents. But the municipality of Veenendaal, for example, ruled in 2022 that it had done nothing wrong. In July 2025, the Central Netherlands court ruled that Veenendaal had indeed acted unlawfully. Delft mayor Marja van Bijsterveldt also insisted for years that she had adhered to the rules and refused to apologize. Her successor, Alexander Pechtold, now acknowledges that the investigation “was, in retrospect, unlawful” and is offering the mosque compensation.
The ten fined municipalities are Veenendaal, Delft, Ede, Tilburg, Huizen, Zoetermeer, Eindhoven, Haarlemmermeer, Gooise Meren and Hilversum. According to the AP, the reports may only be used for legal proceedings, for example by those affected by the investigations.
Wolfsen cannot say whether there will be any sanctions against the agency that conducted the investigations, NTA, and is still used by the Public Prosecution Service and the judiciary to identify terrorism suspects. “We never make any statements about ongoing or ongoing investigations.”
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