I don't think forced euthanasia is right under any circumstances. If a person wants to have no life-saving measures taken, let them fill out a DNR (Do Not Resuscitate order). If they don't want to be on life-support tell them to get a living will. Otherwise, it is up to the families and the courts to help the families decide what is in the best interest of the patient.
Barring any of the measures listed above, people should not be allowed to end a person's life prematurely. There is one northern-European country (I think it is Sweden, but I am unsure.) that pulls the plug w/ or w/o a living will because they have socialized healthcare and the country does not want to pay for life support. Because of this, many non-religious people are suddenly becoming Catholic to avoid death-by-hospitals. I think this is wrong.