4[human organs or tissues or both] from bodies sent for post-mortem examination for medico-legal or pathological purposes.—Where the body of a person has been sent for post-mortem examination—
(a)for medico-legal purposes by reason of the death of such person having been caused by accident or any other unnatural cause; or
(b)for pathological purposes, the person competent under this Act to give authority for the removal of any 1[human organ or tissue or both] from such dead body may, if he has reason to believe that such 1[human organ or tissue or both] will not be required for the purpose for which such body has been sent for post-mortem examination, authorise the removal, for therapeutic purposes, of that 1[human organ or tissue or both] of the deceased person provided that he is satisfied that the deceased person had not expressed, before his death, any objection to any of his 2[human organs or tissues or both] being used, for therapeutic purposes after his death or, where he had granted an authority for the use of any of his 2[human organs or tissues or both] for therapeutic purposes, after his death, such authority had not been revoked by him before his death.