by this section. (As amended by G.N. No. 153 of 1964) Evidence 20. (1) Any invoice or other document submitted or used by an importer or any other person in connection withthe importation of goods in respect of which a prosecution is brought under this Act may be produced as evidence in any criminal proceedings without calling the person who prepared or signed it. (2) In any prosecution for an offence under the provisions of this Act, evidence that any imported goods were shipped at any port of call shall be prima facie evidence that those goods were made or produced in the country within which that port is situated. (3) Where, in any prosecution for a contravention of this Act, the consent of the proprietor of a trade mark is a relevant issue, the onus of proving the consent of such proprietor shall lie on the accused. 21. No person shall within Zambia procure, counsel, aid, abet or be accessory to the commission outside Zambia of any act which, if committed in Zambia, would be an offence under this Act. Aiding and abetting offences (As amended by G.N. No. 153 of 1964) 22. No prosecution for any offence under the provisions of this Act shall be commenced after the expiration of a period of three years reckoned from the date on which the offence was alleged to have been committed or one year next after the first discovery thereof by an inspector, police officer, or customs officer, whichever expiration first happens. Limitation of prosecution 23. Subject to the provisions of this Act, any person who contravenes or fails to comply with any provision of this Act shall be guilty of an offence and shall be liable- Offences and penalties (a) on first conviction, to a fine not exceeding three thousand penalty units or to imprisonment for a period not exceeding one year; (b) on the second or any subsequent conviction, to a fine not exceeding six thousand penalty units or to imprisonment for a period not exceeding two years;