It is up to you to decide if you want to make a health care directive. You have the right to make a one but you do not have to make one.
If you do not have a directive another person can still make treatments decisions for you, if you cannot make them for yourself. Even if you have a directive someone else may have to make decisions if you did not deal with the situation and did not name a proxy. That person will be your nearest family member. Your nearest relative is determined in the following order...
These include relatives by adoption. Except in cases of adoption, the decision of a relative of whole blood is preferred over the decision of a relative of half-blood. If there is more than one person in the same category, for example a number of brothers or sisters, the decision of the eldest will be preferred. The decision of a custodial parent will be preferred over the decision of a non-custodial parent.
In emergency situations where immediate care is urgently required, doctors can provide treatment without having a second doctor agree in writing.
If a relative is making a health care decision for you, they must act according to your wishes, if known. If they have no knowledge of your wishes they must act according to what they believe are your best interests.
If there are no family members, or the family members cannot be found, then your doctor or other health care provider will make decisions for you by consulting with another doctor or health care provider. The second doctor must agree in writing that the proposed treatment is needed.