We must protect the vulnerable in society.  Even without resorting to a moralistic view of the criminal law (i.e. that its function is to stem moral disintegration and to uphold the ‘shared morality’ of society), there is adequate justification for age of consent laws. Society has a vital interest in ensuring that its naturally weaker members are protected from harm, and doing so is precisely the function of the persuasive and coercive powers of the criminal law. It is therefore legitimate for the law to aim to prevent sexual harm to children by criminalising sex with them. Indeed, age of consent sex laws are not the only laws dependent on age. In many countries it is also an offence, for example, to sell tobacco to children, or to employ children below a certain age in the entertainment industry, whether or not the child ‘consents’. Society must recognise the reality that the apparent expression of ‘consent’ by a child is often different from consent expressed an adult. In the case of the former, therefore, it is not always true that saying ‘yes’ is a true expression of human autonomy.  The argument that these laws may cause injustice to someone who truly thought his partner was above the legal age is also a poor one – many countries already provide a defence for such situations