Age for valid consent for operation is -

This question is tricky. Though the valid consent can be given by a person above 12 years of age, but not for the act which may result in death or grievous hurt. A person above 18 years can give valid consent to suffer any harm, which may result from an act not intended or not known to cause death or grievous hurt. A person may be suffering from a disease which is certain to shorten his life. He can give free and informed risk to take the risk of operation, which though fatal in the majority of cases is the only available treatment.