Queensland’s Weapons Act 1990 prohibits possession of a knife in a public place or a school without reasonable excuse. S.51(4) provides an exception “for genuine religious purposes” and cites Sikhism specifically as an example of a religion in which carrying a knife is a genuine religious purpose. S.51(5), on the other hand, declares that “it is not a reasonable excuse to physically possess a knife in a school for genuine religious purposes” – and for purposes of that subsection, the Sikh kirpan is regarded as a knife.
The prohibition came before Queensland’s State Court of Appeal in Athwal v State of Queensland  QCA 156, in which Ms Kamaljit Kaur Athwal argued that the ban was discriminatory. (Though it isn’t stated in the judgment in terms, presumably the ban meant that she couldn’t wear her kirpan on the premises of her children’s school.)