When it comes to medical decision making, the chain of command is usually fairly clear-cut. If you aren't able to make decisions for yourself it falls to your spouse. After that, it goes closest living relative (children take precedence over the patient's siblings, etc...) to be relied on, unless you specifically designate a health-care proxy (a person you designate specifically for medical decision making). When you have a conflict between first-degree relatives, usually we give the benefit of the doubt to the power of attorney, although this is not as legally black and white. If any of you were paying attention several years ago when the Terry Schiavo case was going on: that should have been decided in about 30 seconds, when the husband elected to have the tube removed. The rest of the sideshow was mumbo-jumbo that shouldn't have been allowed to occur. You marry the person, you're electing them to be the default decision-maker, even above your brothers/sisters/parents. Simple as that.
Nurse: "You've been consulted for a second opinion on a patient on comfort care."
Me: "Who is asking me to do the second opinion?"
Nurse: "A woman in the room."
Me: "Who is the power of attorney for this patient?"
Nurse: "The sons. They're the ones who wanted her on comfort care and hospice."
Me: "So I need to know the relationship of this woman to the patient. If the POA is happy with their care, why would I mess with my partner's care plan?"
Nurse: *puts me on hold a minute* "Ok, I have the relationship for you."
Nurse: "She is the great-granddaughter.....in-law."
Me: "You're joking."
Me: "I am more closely related to the patient than she is. I am not coming down there to do a second opinion for a great-granddaughter-in-law who doesn't have a healthcare proxy assigned to her."
Nurse: "Ok, I'll let her know."