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Praxikon

Ruling

Mousse: asking for Mr or Ms when selling a train ticket is not necessary

Date
Status
final
Body
Hof van Justitie van de EU (Eerste kamer), Mousse tegen Commission nationale de l'informatique et des libertés (CNIL) en SNCF Connect
Reference
C-394/23, ECLI:EU:C:2025:2

What it is about

Question: may a transport company require customers to state their title (Mr or Ms) to personalise commercial communication, and is that compatible with data minimisation? Ruling: that processing is not objectively indispensable for performance of the transport contract. It can rest on legitimate interest only if customers were informed of that interest at collection, the processing is strictly necessary and customers' rights, including the risk of discrimination on gender identity, do not override it. The existence of a right to object does not count in assessing necessity.

What this means in practice

Review every mandatory field in your forms: only what is genuinely needed for the service may be mandatory. Title, gender or date of birth for personalised salutation usually are not; make them optional or drop them. If you want to process such data on legitimate interest, that interest must already appear in your privacy information at collection and you must be able to explain why it is strictly necessary.

The GDPR articles concerned

Source: EUR-Lex, arrest C-394/23checked on 15 September 2026

Summary and practical reading by Praxikon. Not legal advice; the source prevails.

Connections

What connects to this development

Case law8 of 10

Guidelines8 of 11

Enforcement and fines8 of 11

Legislation in motion6 of 8