Competency

Although the terms "competency" and "capacity" are often used interchangeably, they differ in a critical manner. "Competency" is a legal term. People are presumed competent until proven otherwise. Competency is also a threshold concept—one is either competent or not competent. (Buchanan et al.). If a person is competent, he or she has the right and the responsibility to make decisions in life, including medical decisions. If a person is incompetent, he or she loses those rights and responsibilities. Someone else must make the decisions for that person.

"Decision-making capacity," on the other hand, is a clinical term that is used to describe varying degrees of mental ability, ranging, for example, from none to slight, moderate, or excellent. Unlike competency, decision-making capacity describes a spectrum of ability (Youngner). Clinicians know that people's inherent ability to make decisions, unlike their legal right to do so, is not an all-or-nothing phenomenon. At one end of the spectrum is the comatose patient, totally unable to make decisions; at the other end is the totally calm, intelligent, rational, decisive, and self-aware person. In reality most patients fall someplace in between. Inherent qualities such as character (e.g., difficulty making decisions), neurosis (e.g., fears and anxieties), and illness-imposed qualities (e.g., pain, fear, isolation, diminished self-image, or dementia) attenuate decision-making capacity to some degree. The critical question, then, is when, on this spectrum of ability, society is willing to take away a person's right and responsibility to make his or hers own decisions.