When a person is unable to make her own decisions and is in need of treatment the doctor may be unable to act without authorization. Merely being married is not enough to grant the authority of one spouse to another for medical treatment. Your spouse does not become your health care agent just because you are married. Everyone needs someone that is designated and authorized to make medical decisions in the event of traumatic injury or incapacity.
A Power of Attorney for health care grants another person to make health care decisions for you. These decisions include whether to refuse life support, medicine, or other procedures that would prolong your life and prevent you from dying. A health care power of attorney also enables your agent to make funeral and burial decisions. Generally this power of attorney enables the agent to make any health care decisions you could make if you had the mental capacity.
A power of attorney for health care is usually written in such a way that it does not become operable until a person becomes incapacitated. This means there must be a way to decide when you are unable to make decisions for yourself. You can write into the power of attorney how this will happen. It could be by a decision of a friend, a family member, a doctor, agreement of more than one doctor, or even by an order of the court after a hearing.