The corollary to the right to refuse treatment is the requirement that, in general, informed consent be obtained before treatment. The Declaration of Lisbon recognises this: "The patient has the right to accept or to refuse treatment after receiving adequate information." The information to be given to the patient is of three kinds, but a special problem in relation to the doctrine of informed refusal places a special duty on the doctor to inform the patient about the possible consequences of refusing treatment. Related topics, such as refusal in part, refusal by a parent or guardian, the novus actus interveniens, the living will, and contributory negligence are touched upon.