s
it "to exercise exclusive legislation in all cases whatsoever over such
district (not exceeding 10 miles square) as may by cession of particular
States and the acceptance of Congress become the seat of the Government
of the United States, and to exercise like authority over all places
purchased by the consent of the legislature of the State in which the
same shall be for the erection of forts, magazines, arsenals, dockyards,
and _other needful buildings_..." But any such supposition will be seen
to be groundless when this provision is carefully examined and compared
with other parts of the Constitution.

It is undoubtedly true that "like authority" refers back to "exclusive
legislation in all cases whatsoever" as applied to the District of
Columbia, and there is in the District no division of powers as between
the General and the State Governments.

In those places which the United States has purchased or retains within
any of the States--sites for dockyards or forts, for example--legal
process of the given State is still permitted to run for some purposes,
and therefore the jurisdiction of the United States is not absolutely
perfect. But let us assume for the argument's sake that the jurisdiction
of the United States in a tract of land ceded to it for the purpose of a
dockyard or fort by Virginia or Maryland is as complete as in that ceded
by them for the seat of Government, and then proceed to analyze this
clause of the Constitution.

It provides that Congress shall have certain legislative authority over
all places purchased by the United States for certain purposes. It
implies that Congress has otherwise the power to purchase. But where
does Congress get the power to purchase? Manifestly it must be from some
other clause of the Constitution, for it is not conferred by this one.
Now, as it is a fundamental principle that the Constitution is one of
limited powers, the authority to purchase must be conferred in one of
the enumerations of legislative power; so that the power to purchase is
itself not an unlimited one, but is limited by the objects in regard to
which legislative authority is directly conferred.

The other expressions of the clause in question confirm this
conclusion, since the jurisdiction is given as to places purchased
for certain enumerated objects or purposes. Of these the first great
division--forts, magazines, arsenals, and dockyards--is obviously
referable to recognized heads of specific con