ne so scores of times, and Congress has
passed legislation carrying our extradition treaties into effect.[196]
Again, Congress could not ordinarily penalize private acts of violence
within a State, but it can punish such acts if they deprive aliens of
their rights under a treaty.[197] Referring to such legislation the
Court has said: "The power of Congress to make all laws necessary and
proper for carrying into execution as well the powers enumerated in
section 8 of article I of the Constitution, as all others vested in the
Government of the United States, or in any Department or the officers
thereof, includes the power to enact such legislation as is appropriate
to give efficacy to any stipulations which it is competent for the
President by and with the advice and consent of the Senate to insert in
a treaty with a foreign power."[198] In a word, the treaty-power cannot
purport to amend the Constitution by adding to the list of Congress's
enumerated powers, but having acted, the consequence will often be that
it has provided Congress with an opportunity to enact measures which
independently of a treaty Congress could not pass; and the only question
that can be raised as to such measures will be whether they are
"necessary and proper" measures for the carrying of the treaty in
question into operation. The matter is further treated under the next
heading.

CONSTITUTIONAL LIMITS OF THE TREATY-MAKING POWER; MISSOURI _v._
HOLLAND

Our system being theoretically opposed to the lodgement anywhere in
government of unlimited power, the question of the scope of this
exclusive power has often been pressed upon the Court, which has
sometimes used language vaguely suggestive of limitation, as in the
following passage from Justice Field's opinion for the Court in Geofroy
_v._ Riggs,[199] which was decided in 1890: "The treaty power, as
expressed in the Constitution, is in terms unlimited except by those
restraints which are found in that instrument against the action of the
government or of its departments, and those arising from the nature of
the government itself and of that of the States. It would not be
contended that it extends so far as to authorize what the Constitution
forbids, or a change in the character of the government or in that of
one of the States, or a cession of any portion of the territory of the
latter, without its consent. * * * But with these exceptions, it is not
perceived that there is any limit to the que