One of the duties of a doctor towards his patients is to obtain consent before any medical examination. Any such examination without prior consent amounts to an assault on the patient. Consent is defined under Indian Contract Act (because Doctor Patient relationship isa contract) as "two or more persons are said to consent when they agree to the same thing in the same sense." Consent may be implied, expressed or informed depending upon the circumstances. But the consent of the patient is not required in situations like medical emergency, for vaccination etc. If the patient is not medically or legally competent to give consent, the consent of the parents or guardians or any person present at the time with the patient can be taken. Any research on a potential subject, removal of organs for transplantation, publication of information obtained during medical examination also require consent of the concerned person.