This is an interesting case and a novel legal argument. However, it was ultimately futile as common sense prevailed in light of the circumstances of this particular case.
A married man who fathered a child with a prostitute, and who had been paying child support for the child, took action in the Federal Magistrates Court with the intent of having the need for the payments legally terminated.
The circumstances were pretty simple; client visits prostitute, client pays prostitute, prostitute gets pregnant and then gives birth to a child, client pays support based on informal agreement, client loses big paying job and decides he does not want to honour the informal agreement, then the prostitute sues for the support.
The legal argument was that the child was in fact a breach of the Trade Practices Act as there was an implied contract between the client and the sex worker that the sex worker would take the necessary measures required to protect themselves, in this case from pregnancy.
In determining the case the magistrate, Grant Riethmuller held that the circumstances of the child's conception makes absolutely no difference to any rights that child has to entitlements under the Child Support Scheme. Therefore, the client was ordered to continue paying child support.