Under which conditions is video surveillance in public space permissible?

• A concrete threat situation
• A clearly defined purpose
• Proportionality
• Transparency (signs)
• Data economy
• A deletion concept

* All six conditions must hold before video surveillance is permissible *

1. Concrete threat (konkrete Gefährdungslage): a real danger, not general unease.
2. Defined purpose: clear in advance what the cameras are for, and only that.
3. Proportionality (Verhältnismässigkeit): the measure must be suitable and necessary, and the intrusion must stand in reasonable relation to the goal. A milder means must be preferred.
4. Transparency: people must know they are being filmed, e.g. through signs.
5. Data economy (Datensparsamkeit): record and keep as little as possible.
6. Deletion concept (Löschkonzept): fixed rules for when recordings are deleted.

Smart glasses such as the Ray-Ban Meta AI glasses fail most of these tests: there is no concrete threat, no defined purpose, and the people being filmed have no sign and no way of knowing.

Go deeper:

• Wikipedia: Proportionality (law) — the suitability, necessity and balance test.