Medical Law (Adult Refusal of Medical Treatment)

Refusal of Medical Treatment 1993 Fam 95, Staughton LJ explained
?An adult whose mental capacity is unimpaired has the right to decide for herself, whether she will or will not receive medical or surgical treatment, even in circumstances where she is likely or even certain to die in the absence of treatment.?
Critically evaluate the above statement and explore the circumstances when the courts may consider the best interests of a patient.