If a loved one is unable to make decisions for him or herself, the court may appoint a substitute decision maker, often called a "conservator," but in some states called a "guardian" or other term. A conservator is only appointed as a last resort if less restrictive alternatives, such as a power of attorney, are not in place or are not working.

The standard under which a person is deemed to require a conservator differs from state to state. In some states the standards are different depending on whether a complete guardianship or a conservatorship over finances only is being sought. Generally, a person is judged to be in need of conservatorship when he or she shows a lack of capacity to make responsible decisions or decisions that are in his or her best interests. 

The court usually looks at a number of factors in determining the need for a guardian or conservator, including the following: 

• Comprehension of important medical or financial information
• Appreciation of the importance of medical and financial decisions and understanding the effect of those decisions 
• Ability to make reasonable decisions using the information available 
• Capacity to communicate decisions in a consistent manner
• Ability to maintain a safe environment 

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 person may not be declared incompetent simply because he or she spends money in ways that seem odd to someone else. Also, a developmental disability or mental illness is not, by itself, enough to declare a person incompetent.

Keep in mind that the standard for whether someone is legally incompetent to care for themselves is not always the same as whether they have the capacity to make legal decisions. Proper execution of a legal instrument requires that the person signing have sufficient mental "capacity" to understand the implications of the document.