(1) Unless the contrary intention appears, if a provision of this Act:
(a) would, apart from this section, have an invalid application; but
(b) also has at least one valid application;
it is the Parliament's intention that the provision is not to have the invalid application, but is to have every valid application.
(2) Despite subsection (1), the provision is not to have a particular valid application if:
(a) apart from this section, it is clear, taking into account the provision's context and the purpose or object underlying the Act, that the provision was intended to have that valid application only if every invalid application, or a particular invalid application, of the provision had also been within the Commonwealth's legislative power; or
(b) the provision's operation in relation to that valid application would be different in a substantial respect from what would have been its operation in relation to that valid application if every invalid application of the provision had been within the Commonwealth's legislative power.
(3) Subsection (2) does not limit the cases where a contrary intention may be taken to appear for the purposes of subsection (1).
(4) This section applies to a provision of this Act, whether enacted before, at or after the commencement of this section.
(5) In this section:
"application" means an application in relation to:
(a) one or more particular persons, things, matters, places, circumstances or cases; or
(b) one or more classes (however defined or determined) of persons, things, matters, places, circumstances or cases.
"invalid application" , in relation to a provision, means an application because of which the provision exceeds the Commonwealth's legislative power.
"valid application" , in relation to a provision, means an application that, if it were the provision's only application, would be within the Commonwealth's legislative power.