The standard under which a person is deemed to require a guardian differs from state to state. And even within some states the standards are different, depending on whether a complete guardianship or only a conservatorship over finances is being sought. Generally a person is judged to be in need of guardianship when he or she shows a lack of capacity to make responsible decisions.
A person cannot be declared incompetent simply because he or she makes irresponsible or foolish decisions, but only if the person is shown to lack the capacity to make sound decisions. For example, a man may not be declared incompetent because he spends money in ways that seem odd to someone else. In addition, a developmental disability or mental illness is not, by itself, enough to have a person declared incompetent.
Elder Law Answers September 2009