Like when they used the Covid app location data to investigate a murder?[1]
[1]: https://metro.co.uk/2022/01/12/german-police-tracked-down-re...
[1]: https://metro.co.uk/2022/01/12/german-police-tracked-down-re...
These things aren't a one-and-done matter of legislation or constitutions, they rely on constant pressure on every case.
(and I explicitly said the EU system does not guarantee privacy against law enforcement! Because total privacy for crime is very unpopular and politically unsustainable)
German police are being investigated for using Covid-tracking data as part of a probe into a death.