On May 8, 2024, the American Bar Association Standing Committee on Ethics and Professional Responsibility issued formal opinion 511 containing guidance for lawyers who request advice from their colleagues through a listserv. Specifically, the Opinion summary states that:
"Rule 1.6 prohibits a lawyer from posting questions or comments relating to a representation to a
listserv, even in hypothetical or abstract form, without the client’s informed consent if there is a
reasonable likelihood that the lawyer’s questions or comments will disclose information relating
to the representation that would allow a reader then or later to infer the identity of the lawyer’s
client or the situation involved. A lawyer may, however, participate in listserv discussions such as
those related to legal news, recent decisions, or changes in the law, without a client’s informed
consent if the lawyer’s contributions will not disclose, or be reasonably likely to lead to the
disclosure of, information relating to a client representation. "
As far as I can tell, the OHIO RULES OF PROFESSIONAL CONDUCT do not mention listserv conduct specifically, but Ohio Rule 1.6 does pertain to client confidentiality.