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Direct answer · GDPR

May an organisation make it mandatory to provide data that are not needed for the service?

Short answer

Only if those data are really needed. Personal data must be limited to what is necessary (Article 5(1)(c)). According to the Court of Justice in Mousse, a transport company may not require the form of address (Mr or Mrs) under the contract, as it is not objectively indispensable. Legitimate interest requires that the customer was informed, the processing is strictly necessary and their rights do not override it.

Direct answer · GDPR

Data minimisation and necessity for a contract

Only if those data are really needed. Personal data must be adequate, relevant and limited to what is necessary (Article 5(1)(c)). The Court of Justice held in Mousse that a transport company may not require the form of address (Mr or Mrs) on the basis of the contract (Article 6(1)(b)), because it is not objectively indispensable for the transport. Legitimate interest (Article 6(1)(f)) is only possible if the customer has been informed of that interest, the processing is strictly necessary and the rights of the customer, such as the risk of discrimination based on gender identity, do not override it.

For you to establish

  • What exactly does the organisation use the data for?

Articles

Case law

  • Mousse (CJEU, C-394/23, ECLI:EU:C:2025:2, 2025-01-09)Operative part: the form of address is not necessary for the transport contract; strictly necessary under legitimate interest.
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Zahed Ashkara, jurist and freelance AI & Privacy Consultant

Behind this page

Zahed Ashkara

Freelance AI & Privacy Consultant, jurist