Without prejudice to subsection (8) of section 67 of the Summary Proceedings Act 1957, in any proceedings against any person in respect of any offence against this Act or against any regulations made under this Act in which it is proved that he had in his possession any controlled drug, or did any act in relation to a controlled drug which would have amounted to that offence if such act were not done pursuant to section 8 or to a licence under this Act or as otherwise permitted by regulations under this Act, the burden of proving that he had such controlled drug in his possession, or did such act, pursuant to the said section 8 or to any such licence or as so permitted shall lie on him.