It is generally accepted that a patient has the right to refuse treatment even if such refusal may cause injury or death.
A “living will” can be defined as an advanced directive by a person to the effect that if at any time he should suffer from an incurable disease or injury, which cannot be successfully treated, life-sustaining treatment should be withheld and the patient left to die naturally. In other words, as soon as the person is not capable of instructing a doctor, the advanced directive in the form of the living will, will become relevant.
This makes the decision for the family and the doctor easier to switch off, for example, life-sustaining machines where the patient is braindead and there is no hope whatsoever that the person will recover. This can obviously prevent a lot of trauma and medical costs.
A living will therefore pertains to passive euthanasia.
It is important to rather have a living will as a separate document from your normal will to enable the living will to be handed to your doctor and family.
The living will can also provide for organ donation.