May my landlord install a fingerprint lock on the front door?

Fingerprint, face-recognition, and iris locks = biometric identification = special category data (GDPR Art. 9(1)(b)). Strictest GDPR regime. Landlord context makes it almost impossible: "consent" between landlord and tenant is rarely freely given — tenant is dependent on landlord (same logic as employer-employee). EDPB guideline 2018 confirms this. When IS it allowed? Theoretically only under Art. 9(2)(a) (explicit + voluntary consent, with demonstrable free choice) or (g) (substantial public interest with statutory basis). In practice: almost never. Almost always required: ALTERNATIVE — regular key or PIN choice. If only biometric is offered without alternative = no free consent = unlawful. Routes if landlord wants biometric-only lock: (1) Request alternative in writing. Landlord must offer. (2) On refusal: rental committee + AP complaint. (3) Landlord can still install, but must also give you traditional key/code. AP fine 2024: large landlord organisation €100k for mandatory biometric check-in without voluntary alternative. For commercial locks (smart locks Yale, Aqara): consumer choice, free use. But watch out for biometric storage location + cloud uploading.