Source: Professional Responsibility Blog: Can an attorney disclose very old confidential information because of its historical value?
Interesting post by Prof. Alberto Bernabe. FWIW if there is no identifiable living person who would be harmed by the disclosure, I think that the old file can be donated to a library. A much harder case is that of, for example, about the files of the lawyers `cold war’ spies like Alger Hiss or the Rosenbergs for whom there are living heirs – who have explored, explained, and assessed their conduct . – gwc