I'm very sorry to hear about your loss. The law does allow people to refuse treatment, but if your daughter wasn't mentally capable of making such a decision, you may be able to make a case for wrongful death. I think this is certainly a matter which you should seek the input of an experienced medical negligence lawyer on.
I did find this quote which seems to support your feelings on the matter: "Prior to discharging a patient AMA, the physician should be convinced that the patient has given and informed refusal, and has had an opportunity to ask questions. The physician must determine and document that the patient is functionally competent. Refusal of care is invalid for persons who have been committed to the care of the hospital by legal proceeding or who are not competent."
Here are some articles you might be interested in:
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