Ex Parte Nelson (No 1)  HCA 33; (1928) 42 CLR 209 (22 October 1928)
Sec. 92, as explained, makes an exclusive legislative jurisdiction in that domain of Australian life. It follows that any legislative constraint whatsoever on those subjects by the State is a derogation of the guaranteed immunity. Those considerations would have to remain in the discretion of the grantor of the power or in that of any other authority to whom it is entrusted. And so here in the sphere of inter-State trade, any regulation of the subject by the State legislature is a restraint of action forbidden by sec. 92. The State cannot, on the principle of doing evil that good may come, transgress the clear prohibition in sec. 92. It can no more do that on the ground of the ultimate welfare of the people of the State or the Commonwealth, than could a schoolmaster, forbidden to punish his scholars, inflict corporal punishment on them on the plea that they will become better men. If a legislative authority is forbidden to pass a law inflicting the punishment of death, an enactment providing for capital punishment would not be saved on the ground that upon the whole it made human life safer. In that sphere, the Commonwealth only is the legislative regulator. As to other departments, sec. 92 is silent, and the State is unfettered unless a fetter is elsewhere imposed. But it may be repeated, and it cannot be too often repeated, that there is no room for interposing qualifications in the exclusion of the State from the designated subject matter. The concept will not permit it. Whatever restraints and prohibitions are legally possible are entrusted by the Constitution to the Commonwealth Parliament, as alone competent to speak impartially for the people of Australia as a whole, and to hold the balance evenly between the States.