The Medico-Legal Approach to the Assessment of Testamentary Capacity: A Systematic Review.

An increase in will challenges on the grounds of lack of capacity and undue influence is anticipated in the face of an imminent transfer of generational wealth by a growing elderly population with a high prevalence of cognitive impairment. Medical experts will be a necessary element of litigation to help the courts make the best legal determinations involving cognitive and psychiatric functions that may affect mental capacity and vulnerability to influence. We conducted the first systematic literature review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses ("PRISMA") guidelines in order to identify articles that addressed a comprehensive medico-legal approach to the assessment of testamentary capacity. Only 12 articles met the criteria for the systematic review. Banks v Goodfellow ("Banks") continues to be considered the leading case that defines the criteria for the courts and lawyers in the determination of testamentary capacity. However, quantitative data to support this impression is nowhere to be found. Moreover, unpredictability remains a hallmark of cases involving will challenges. Since calls for increased medico-legal collaboration and updates to the Banks test have not been evaluated, a scoping review of a large number of judicial decisions is required to better understand the current approach to this legal determination. Relevant variables could be used to develop a predictive model that would help lawyers and medical experts in this important societal collaboration.