only agent in cases where the federal power is exclusive. When
that power wholly occupies the field, as in the case of the control
of the Customs, the State Governments are ex necessitate out of
that field, which knows as occupants one Government and one
people, the Australian Government, and the Australian people
who give it life. So in the domain of exclusively national legis-
lation there is no room for State Parliaments or Executives.
They have great powers, which this Court has guarded, and will
guard, But as far as the law of the Constitution is concerned,
State Governments are supreme in their sphere and powerless
beyond it. And this is also true of the Australian Government
in its turn. In a note to the case of Stockton v. Baltimore and
New York Ruilway &e. Co. (1), a very instructive case, Dr. Thayer,
Weld Professor of Law at Harvard University, a high authority,
saysat p. 2,068 of his Cases on Constitutional Lav, in relation to
the power to regulate commerce with foreign nations, and among
the several States, &c.: - " We think that the power of Congress is
supreme over the whole subject, unimpeded and unembarrassed by
State lines or State laws; that, in this matter, the country is one,
and the work to be accomplished is national; and that State
interests, State jealousies, and State prejudices do not require to be
consulted. In matters of foreign and interstate commerce there
are no States." That these words truly express the nature and
extent of the commerce power, as interpreted by the Supreme
Court of the United States, there can not be a doubt. So long as
the legislative exercise of the power is kept within its ambit,
that is, so long as the federal grantee does not attempt to
regulate the purely internal and domestic commerce of a State,
such exercise and its executive consequences cannot be hindered
or nullified in any part by any legislative or executive act on the
part of a State. A Statute of a State - the highest exercise of
power of which it is capable - would be void so far as it pur-
ported to authorize such an act; and there is no constitutional
authority in the Executive of the State to do that which no
Statute of its Parliament could make lawful. It follows that in
such a case no citizen can justify under an authority purporting to
be granted him by a State Executive, for that is no authority at
(1) 32 Fed. Rep., 9.