Innocent publication of advertisement
20.  In proceedings for an offence under this Act committed by the publication of an advertisement, it is a defence for the person charged to prove —
(a)that the person’s business is to publish or arrange for the publication of advertisements; and
(b)that the person received the advertisement for publication in the ordinary course of business and did not know and had no reason to suspect that its publication would amount to an offence under this Act.