Unfortunately it's not a clearly written clause. It's derived from the dignity of humans and similar general terms. So the interpretation has changed over the decades. As long as the GDR existed it was clearly considered a property of a totalitarian state. Existed in the GDR (East) but unthinkable in the Federal Republic (West). Maybe 15 years after reunification (don't quote me on the exact number) a permament nationwide tax id was introduced. With the promise that its usage will forever be limited to tax offices and exchange with any other authorities is illegal. Another 15 years later that promise was "forgotten" and now the tax id can be exchanged with many authorities. It's relatively new and probably not widely used yet. But the dams have been opened.
Yes, that's a better explanation of the constitutional status, thank you! (Supreme court decision vs. an explicit clause in the constitution.)
FWIW, I think in this age of massive databases that can be effortlessly joined on fuzzy matching criteria, the lack of a unique person identifier is more of a hurdle for legitimate use cases than a safety measure against government or corporate overreach.
One good thing about it is the complete lack of the horrible "SSN as both primary key and bearer authentication token" pattern that's commonplace in the US, though – but the alternatives are pretty annoying, in my experience.
That sounds a bit like how SSN use in the US has broadened from its original scope. Any government power, once granted, seems only to ever increase in scope.
