This argument often appears as 'doctors should not be allowed to play God'. Since God arguments are of no interest to people without faith, it's presented here with the God bit removed.
Doctors should not be allowed to decide when people die:
Doctors do this all the time
Any medical action that extends life changes the time when a person dies and we don't worry about that
This is a different sort of decision, because it involves shortening life
Doctors take this sort of decision all the time when they make choices about treatment
As long as doctors recognise the seriousness of euthanasia and take decisions about it within a properly regulated structure and with proper safeguards, such decisions should be acceptable
In most of these cases the decision will not be taken by the doctor, but by the patient. The doctor will provide information to the patient to help them make their decision
Since doctors give patients the information on which they will base their decisions about euthanasia, any legalisation of euthanasia, no matter how strictly regulated, puts doctors in an unacceptable position of power.
Doctors have been shown to take these decisions improperly, defying the guidelines of the British Medical Association, the Resuscitation Council (UK), and the Royal College of Nursing:
An Age Concern dossier in 2000 showed that doctors put Do Not Resuscitate orders in place on elderly patients without consulting them or their families
Do Not Resuscitate orders are more commonly used for older people and, in the United States, for black people, alcohol misusers, non-English speakers, and people infected with Human Immunodeficiency Virus. This suggests that doctors have stereotypes of who is not worth saving