So the original premise was

scenario 1:

> Doctor: undergo my recommended treatment or you will die > Patient: no

scenario2:

> Patient: Doctor, please chop off one of my hands for no good reason > Doctor: no

lets add a scenario 3:

> Doctor: I need to chop off your hand within the next hour or you will die > Patient: no

What do you think the doctor should do?

The doctor should not cut off the hand, in your scenario.

A more realistic scenario is probably DNR orders, which doctors do honor.

Doctors often do not honor DNR orders because there is no penalty for disobeying them while they can face severe penalties for failing to save someone's life if their DNR order is invalid for some reason.

According to an article I found [0], a doctor may at least theoretically be subject to legal penalties for disregarding a DNR.

> Wrongful life. Theoretically, if a patient is resuscitated in the OR against the patient's wishes, a “wrongful, life” lawsuit could be filed. Under this suit, a patient could request compensation for ensuing expenses for continued life, negligence, and battery. An Ohio appellate court reviewed a case in which a patient was resuscitated after a DNR order was documented on his chart.12 Although the court in this particular case rejected the wrongful life theory, it did uphold the possibility that battery and negligence had occurred. This case has made it certain that the advance directive is an important component of a patient's chart.

[0] Evelyn Eckberg RN: The Continuing Ethical Dilemma of the Do-Not-Resuscitate Order http://onlinelibrary.wiley.com/doi/10.1016/S0001-2092(06)626...

Yeah in theory their could be penalties, but in practice no court wants to discourage doctors from saving people's lives.

scenario 4:

> Doctor: I need to chop off your hand for no good reason > Patient: no