[mr_luc]

Above was a quote from Carpenter, and the Court seems to have called out that the completeness of the record meant it recorded them, 'not only in public thoroughfares', but also private homes and doctor's office and so forth.

It does seem like that's an element, then -- this is not to say that it's sufficient for anything, since obviously a sufficiently good record of where one goes on public thoroughfares would fail the same test ('reliably reveals that so-and-so went to visit a specialist doctor, divorce attorney, and brothel all on the same day')

[estearum]

It's the completeness of the record that matters, not the publicness of it.

[mr_luc]

Yes that feels like a good characterization.

Which, I would say, does seem a lot less black-and-white than the cell phone example, and anyone who thinks it's all settled now might be in for a surprise.