In a charge under stock theft legislation for possession of stolen stock, once the accused provides an explanation for possession, the court must assess whether the accused genuinely and reasonably believed the person from whom they received the stock was the property owner or duly authorized to deal with it. The genuineness of belief is assessed subjectively, while the reasonableness is assessed objectively - would a reasonable person in the same circumstances have entertained the same belief. The duty to establish a seller's identity and verify ownership lies with police authorities, not with the purchaser. Where an accused takes all reasonable steps to obtain proper veterinary and police clearances, provides correct personal identification, and the seller presents documentation and identity particulars that would satisfy a reasonable person, the belief in lawful acquisition is both genuine and reasonable, precluding conviction for possession of stolen stock.