A power of attorney to consent to medical care may be limited in whatever way the person delegating the right wishes, consistent with public policy. Put simply, a person may not use a power of attorney to force treatment decisions that would otherwise be improper. For example, the person with a power of attorney may not authorize active euthanasia or force the physician to provide care that the physician would not otherwise provide.

If the person delegating the authority to consent is suffering from a terminal illness, it is usual to state that the power of attorney to consent to medical care is to remain in effect until revoked. It is also usual for spouses to execute prospective powers of attorney that are of indefinite duration, called durable powers of attorney. A durable power of attorney remains in force if the patient becomes legally incompetent. In some states, a power of attorney expires when the patient is declared legally incompetent. In all states, the court may supersede a power of attorney by appointing a guardian for the person. The courts are interested in perpetuating the person’s wishes and will usually honor a guardian who is proposed in the power of attorney. For the power of attorney to be durable, it must recite that the patient wants the power of attorney to remain effective if he or she becomes incompetent. If the person is concerned only with temporary incapacity secondary to medical treatment, the power of attorney to consent to medical care should have an expiration date.

A power of attorney to consent to medical treatment may be unlimited, or it may authorize only certain medical decisions. It is even possible to execute more than one power of attorney to consent to medical treatment, as long as each document is limited and does not conflict with the others. This might happen when the person executes a general power of attorney to consent to routine medical care and a specific power of attorney to refuse or terminate life support.

In some situations, it is difficult to determine what authority the patient intended to delegate. The patient may have delegated the right to consent to more than one person. The power of attorney may be inconsistent, delegating the right to consent to only part of the necessary care or delegating the authority to consent to improper care. A physician confronted with an ambiguous delegation of the authority to consent to treatment or with improper delegations should ask a court for clarification.