The very general statement has been thought warranted that the
interpretation of any paramount concurrent legislative power of
the Commonwealth always involves a question of the limits inter
se of State and Federal constitutional power. This is not the
same thing as saying that all questions whether the Commonwealth
has exceeded a power conferred by s. 51 are questions inter se.
For it is not all powers conferred by s. 51 that are in every respect
paramount. Paragraph (xxxvi.) confers a power by reference to a
number of sections of the Constitution concerning matters with
respect to which the Parliament may provide : see ss. 3, 7, 10, 22,
24, 29, 30, 31, 34, 39, 46, 47, 48, 65, 66, 87, 96, 97. They are not
matters with which the States could have any concern and, if a
common boundary between the Federal power over them and
State power is conceivable at all, it would, I suppose, be found
to be a boundary between a State power and a Federal exclusive
power. Then the power with respect to bounties conferred by
par. (iii.) is made exclusive by s. 90. The power to impose taxation
which forms part of the power to make laws with respect to taxation
conferred by par. (ii.) has been regarded as parallel and concurrent
with the taxing power of the States, though no doubt par. (ii.)
extends to incidental matters over which the Federal power may
be paramount. In the same way, except as to incidental matters,
it is not easy to see how any exercise of the powers conferred by
pars. (x.), (xxvill.), (xxx.), (xxxiii.) and (xxxiv.) could affect State
law as a result of the application of s. 109. However s. 51 (xxxi.)
confers a concurrent power, but if a conflict of legislation passed
in its exercise with State legislation arose s. 109 would undoubtedly
apply. Nevertheless there are certain features about a power to
make laws with respect to the acquisition of property upon just
terms which made it uncertain whether in all respects its interpre-
tation did involve an inter se question. The central purpose of the
power, the acquisition of property, is not calculated to bring about
a collision of Federal and State authority until both the Common-
wealth and a State set about acquiring the same property. Legisla-
tion upon matters incidental to the acquisition of property might
be of a more general character and raise questions about a common