All or most courts recognize what they call the "crime-fraud exception" to attorney-client privilege protection. Although courts take differing positions on numbering this crime-fraud exception's factors, most agree on the basic requirements.
In US Pain Foundation, Inc. v. Daponte, the court articulated a two-part test on which a litigant must carry the burden of proof: "the existence of probable cause" (1) that the adversary had engaged in "'the perpetration or attempted perpetration of a crime or fraud'" and (2) "'that the communications were in furtherance thereof.'" Dkt. No. (X07) HHD-CV-20-6159647-S, 2023 Conn. Super. LEXIS 339, at *13 (Conn. Super. Ct. Mar. 10, 2023). Four days later, the court in Lewis v. Louisiana State University, Civ. A. No. 21-198-SM-RLB, 2023 U.S. Dist. LEXIS 43988, at *8 (M.D. La. Mar. 14, 2023), articulated a three-part test which followed the same basic concept, but added the obvious element that the challenged attorney-client communication "bears a relationship to the alleged crime or fraud."
Other courts use other numbering variations, but they all essentially contain the same requirements: a litigant must establish a prima facie case that the adversary attempted or engaged in a crime or fraud, which its attorney-client communications furthered. If a litigant satisfies that standard, the court then reviews the communications in camera to make its own assessment of the crime-fraud exception's applicability to each challenged communication.