Mr Ross submitted that because s.7 of the Act defined an import as having the same meaning as that under the Customs Act that assimilated that aspect of Teh to the present case. He claimed that mens rea was always an element of the offence if it involved importation because there was only one form of importation. However, this argument ignores the development of principles upon which the Court acts in determining whether in some cases (whether or not importation is involved) that guilty knowledge is simply not an element (absolute liability) and others where there is a presumption that mens rea is required before a person can be found guilty of a grave criminal offence but that the prosecution may rebut it by proving the accused's knowledge, or in some cases it being regarded as one of strict liability avoidable if the offence was committed when the accused honestly and reasonably held a mistaken belief in facts which if true exculpated the accused from any offence. Whilst it is true that s.50 of the Customs Act 1901 draws no distinction between the meaning of "import" in relation to goods or narcotic substances, other considerations relating to (i) the subject matter, (ii) purpose of the enactment, (iii) the penalties provided, and (iv) the language of the statute itself, are relevant matters to consider. Importation of prohibited products is not the only area in the law in which there is a tension between the legislative objective of dealing with a grave social evil and the principle that the protection of the liberty of the subject commonly involves resistance to the finding of guilt of a breach of the criminal law in the absence of a guilty mind. Brennan, J. in Teh (at 567) stated that: