Australia did not become a party to the Convention for the Suppression of the Traffic in Persons and of the Exploitation of the Prostitution of Others when it was implemented in 1949. It has implemented in 1999 the Protocol to Prevent, Suppress and Punish Trafficking in Persons, especially Women and Children, supplementing the United Nations Convention against Transnational Organized Crime, to which it is a party. Australia has also ratified on 8 January 2007 the Optional Protocol to the Convention on the Rights of the Child on the Sale of Children, Child Prostitution and Child Pornography, which requires it to prohibit, besides other things, child prostitution. For the purpose of the Protocol, a child is any human being under the age of 18, "unless an earlier age of majority is recognised by a country's law". In all Australian jurisdictions, the minimum age at which a person can engage in prostitution is 18 years, although it is argued against the age of consent, and it is always illegal to engage another in prostitution.