What is the right to refuse medical interventions?

Theresa Marie "Terri" Schiavo case of the United States

The consistent refusal to intervene on behalf of Schiavo’s parents’ desire to continue nutrition and hydration is a reaffirmation of the right to refuse medical care even for mentally incapacitated patients and that artificial nutrition and hydration are medical treatments. In theory, the right of patients to refuse medical therapy can be limited by four state interests in: Preservation of life, Prevention of suicide, Protection of third parties such as children and Preserving the integrity of the medical profession. In practice, these interests almost never override the right of competent patients and incompetent terminally ill patients who have left explicit advance directives.