“The attorney–client privilege is one of the oldest recognized privileges for confidential communications.[2] The United States Supreme Court has stated that by assuring confidentiality, the privilege encourages clients to make “full and frank” disclosures to their attorneys, who are then better able to provide candid advice and effective representation.[3]”
Some things are excluded...
From Wiki
Well, if age of the instituton is a determining factor then the Church is older than English law. Anyway, as long as we are upending institutions, why not go all the way. Think of the efficiency...