What must a patient give to have surgery performed on them legally?

For surgery to be performed legally, a patient must provide informed consent. This means that the patient understands the nature of the procedure, the risks involved, expected outcomes, and any alternative treatments available. Informed consent emphasizes the patient's right to make decisions about their medical care based on a clear understanding of what they are agreeing to.

While written consent is often the preferred method of obtaining consent and may be required for certain procedures, the essence of legal consent is that it is informed. Verbal agreements can sometimes be used in practice, but they do not always carry the same legal weight, especially for non-emergency surgical procedures. Emergency consent may apply in situations where the patient is unable to provide consent and prompt action is necessary to prevent serious harm, but it's not the standard procedure for planned surgeries when the patient is able to communicate their wishes.