The controversy surrounding the issue whether or not mental health professionals in South Africa should offer opinion testimony that touches upon the ultimate-issue has been ongoing and remains unsettled. This controversy has left the exact place of the ultimate-issue rule in balance hence causing uncertainty. This uncertainty has impacted negatively on the advancement of opinion testimony by mental health professionals. One notable area that has been affected is the one pertaining to child sexual-abuse cases. The authors trace the historical foundations surrounding the development of the ultimate-issue rule. It is demonstrated that the rule finds its basis in justice systems with jury trials, with the aim of the rule having been to ensure that experts do not usurp the role of the jury. Historically, juries were not schooled in law hence the need to screen the evidence they received ensuring that experts' opinions did not awe them to a point of them relinquishing their decision-making powers. In this context, the unsoundness of the rule in non-jury systems such as South Africa's (where decisions are made by judges schooled in law) is underscored. It is highlighted that the policy considerations surrounding the development of this rule are not applicable to South Africa. Recommendations are made for its express abolition by way of statutory guidelines.