Decisional Capacity and Personality Disorders: Substantially Unable or Substantially Unwilling?

Abstract Capacity assessments are performed when there is suspicion that a person is unable to adequately care for their physical, medical, or financial well‐being. The purpose of these assessments is to inform the legal system as to whether or not guardianship may be necessary. It is well established that certain mental illnesses, such as neurocognitive disorders (dementia) or psychotic disorders (like schizophrenia), may diminish capacity and, in some cases, lead to the need for establishment of a legal guardian. However, personality disorders are another common category of mental illness which may impair decision‐making. There is very little information in the literature about how or why these disorders could impair capacity, and thus, it can often be difficult to discern whether clients with personality disorders are substantially unable to care for themselves—versus unwilling to act in a way contrary to their ingrained habits. We present a series of three cases in which clients are determined to lack capacity primarily mediated by a personality disorder diagnosis. They are demonstrated to have mild deficits in cognitive functioning, but they show impaired decision‐making out of proportion to these deficits. In all three cases, it is apparent that the personality disorder is substantially impairing their ability to care for themselves. Discussion includes consideration for ways to incorporate evaluations of cognitive function, activities of daily living, and personality considerations into capacity assessments, and how to approach recommendations (such as guardianship vs. less restrictive option) based on both level and scope of impairment.