The rules of IC and the way to design the surrogate for critically ill patients differ across countries [5]. Many countries recognise the figure of a designated surrogate or proxy, while the other countries give the legal right to the relatives. Furthermore, different countries recognise the legal validity of the advanced directives of treatment. However, the types and the contents of the advanced directives of treatment vary across countries. The most common advanced directives of treatment are the living will and the power of attorney or healthcare proxy. The living will is a document designed to control future healthcare decision or treatment when patients become incompetent. The living will describes the type of medical treatment the person would want or would not want in state of unconsciousness. The power of attorney, also called healthcare proxy, is a legal document in which the patient names a person to be his proxy to make all your healthcare decisions if he/she becomes unable to do so. The person indicated in this document has the right to consent to medical treatment (Table 16.1).