A more thorough explanation:

The doctrine of substituted judgment is a principle that allows a surrogate decision-maker to make decisions on behalf of an incompetent patient. The decision-maker tries to establish, with as much accuracy as possible, what decision the patient would make if they were competent to do so. This principle is used when the patient was once competent but is no longer able to make decisions.

For example, if a patient is in a coma and unable to make decisions about their medical treatment, the doctrine of substituted judgment would allow a family member or legal guardian to make decisions on their behalf based on what the patient would have wanted if they were able to communicate.

The standard of proof for the doctrine of substituted judgment is by clear and convincing evidence. This means that the decision-maker must provide strong evidence to support their decision.

Overall, the doctrine of substituted judgment is used to ensure that the patient's wishes are respected even if they are unable to communicate them.