There are some mathematical definitions [1], but the fundamental problem is that with enough cross-referencing between databases it's hard to say anything for s

There are some mathematical definitions [1], but the fundamental problem is that with enough cross-referencing between databases it's hard to say anything for sure [2]. You never know what data other people might publish in the future. I'm not aware of any legal definitions, but given the thorniness of reidentification I would assume they're insufficient. [1] https://en.wikipedia.org/wiki/K-anonymity https://en.wikipedia.org/wiki/K-anonymity [2] https://www.wired.com/2007/12/why-anonymous-data-sometimes-isnt/ https://www.wired.com/2007/12/why-anonymous-data-sometimes-i...