The attorney-client privilege prohibits “the discovery of confidential communications, oral or written, between an attorney and his [or her] client with reference to…litigation pending or contemplated.” State ex rel. Terminal R.R. Ass’n of St. Louis v. Flynn, 25 S.W.2d 69, 73 (Mo. 1953). The attorney-client privilege is destroyed if a client shares the privileged information with a third-party or if a third-party outside of the attorney-client relationship is present for the communication.
The common interest doctrine is an extension of the attorney-client privilege. It allow parties with a community of interests to preserve the privilege’s protections where the parties had joined forces for the purposes of obtaining more effective legal assistance. State ex rel. Winkler v. Goldman, 485 S.W.3d 783, 790 (Mo. Ct. App. 2016). As a result, the attorney-client privilege is not destroyed when the communication is shared with a communication with a third-party that shares a common interest in the outcome of the litigation and where the communication in question was made in confidence. Lipton Rlty. v. St. Louis Housing Authority, 705 S.W.2d 565, 570 (Mo. Ct. App. 1986).