A guardian assumes decision-making rights for the incapacitated person.
Check out this succinct description of Adult Guardianship Mediation taken from a journal article by Eva Soeka in 2000. This article is a good source for understanding what it is and what it involves.
“Adult guardianship is a drastic legal remedy where a person is determined to be legally incapacitated or incompetent and incapable of handling personal or financial affairs or both. Adult guardianship may result in the loss of basic personal, contractual, and legal rights, such as choosing where to live, handling personal finances, making decisions about medical care and even, in some states, voting or getting married. A guardian assumes decision-making rights for the incapacitated person.”
“One of the primary reasons [mediation works] is that it includes the older person in the decision-making process. Mediation also allows for the participation of family members and other non-family member caregivers, such as friends or neighbors. It encourages consensus-building among those who care about the proposed ward and it helps preserve relationships among those individuals. It ultimately ensures that the proposed ward receives the best and most appropriate care possible. As a result, mediation often avoids the emotional trauma of an adversarial court proceeding.”