Rule 37.
A person waives his right or privilege to refuse to disclose or to prevent another from disclosing a specified matter if he or any other person while the holder thereof has (a) contracted with anyone not to claim the right or privilege or, (b) without coercion and with knowledge of his right or privilege, made disclosure of any part of the privileged matter or consented to such a disclosure made by anyone.
A disclosure which is itself privileged or otherwise protected by the common law, statutes or rules of court of this State, or by lawful contract, shall not constitute a waiver under this section. The failure of a witness to claim a right or privilege with respect to 1 question shall not operate as a waiver with respect to any other question.