Section 20: Certificates and presumptions

(1) In any proceedings under this Act or the regulations the production of a certificate purporting to be signed by an analyst shall be prima facie evidence of the matters stated therein; but the party against whom the certificate is produced may require the attendance of the analyst for the purpose of cross-examination.
(2) A certificate such as is mentioned in subsection (1) of this section shall not be received in evidence unless the party producing it has not less than three days before the trial supplied a copy thereof to the party against whom it is intended to be produced and has notified him in writing of the intention to produce it.
(3) Where any employee or agent commits an offence under this Act, his employer or principal shall be deemed to have committed the offence and be liable to be proceeded against and punished accordingly, whether or not the employee or agent has been prosecuted for the same offence; and for the purpose of this subsection, any person selling or ostensibly employed to sell on behalf of another person shall be presumed to be employed by him.
(4) Where, in any proceedings against any person for manufacturing any adulterated food or drug contrary to the provision of this Act or the regulations, it is established that the food or drug is one which, under the regulations, becomes adulterated if any prescribed substance is added thereto, and that that substance was found in his possession or on his premises, it shall be presumed, unless the contrary is proved, that the food or drug manufactured by him is adulterated.