Final answer:
Patients lacking decision-making capacity are treated under implied consent or decisions made by a legally authorized representative. The principle of autonomy requires respecting a patient's right to self-determination, while nonvoluntary passive euthanasia may apply in strictly regulated scenarios without a patient's consent.
Step-by-step explanation:
A patient without capacity would be treated under implied consent or through decision-making by a legally authorized representative, such as a family member or legal guardian. The principle of autonomy in medical ethics states that patients have the right to make decisions about their healthcare based on their values and preferences. However, when they cannot make decisions, consent may be given by a proxy. This is legal consent provided by parents for children, or by legal guardians for adults who cannot give informed consent. There are situations where a patient may not have available family or a legal advance directive; in such cases, medical professionals may proceed with nonvoluntary passive euthanasia, which means providing only palliative care or allowing natural death, but this is highly regulated and context-specific to ensure ethical standards are met.