Two prerequisites should exist before a court appoints a guardian. The first is that the individual must be incompetent in at least one important area of his/her life. That decision is often easy to determine as a result of real-life experiences. Can the person take care of himself and his property, or is he at risk if left on his own?

Second, there must also be a present need for the guardianship. A person may have significant deficits in his life, but his support network – families, friends, service providers, etc. – may be so strong that guardianship is not necessary. The expression, "If it ain’t broke, don’t fix it" may be applicable. If guardianship does become necessary at a later point in the individual’s life, it can be sought at that time.

There are some situations where guardianship may be an asset to protecting someone’s health and safety, to asserting their rights, and even to helping someone express himself. An individual who is nonverbal and who has profound mental retardation, may well need a guardian, especially if he resides in an institutional setting without family support and monitoring. An individual may well need a guardian if his mental capacity is in doubt and if he at the same time has significant medical issues that require frequent consent to medical procedures.

In accord with the principle of self-determination, it may also be useful – in assessing whether or not person needs a guardian – to evaluate the extent to which the individual can participate in the decisions that affect his own life.