are regulations of commerce, in a most
important particular, affecting it in those respects in which it is
under the exclusive authority of Congress. I state this first
proposition guardedly. I do not mean to say, that all regulations which
may, in their operation, affect commerce, are exclusively in the power
of Congress; but that such power as has been exercised in this case does
not remain with the States. Nothing is more complex than commerce; and
in such an age as this, no words embrace a wider field than _commercial
regulation_. Almost all the business and intercourse of life may be
connected incidentally, more or less, with commercial regulations. But
it is only necessary to apply to this part of the Constitution the
well-settled rules of construction. Some powers are held to be exclusive
in Congress, from the use of exclusive words in the grant; others, from
the prohibitions on the States to exercise similar powers; and others,
again, from the nature of the powers themselves. It has been by this
mode of reasoning that the court has adjudicated many important
questions; and the same mode is proper here. And, as some powers have
been held to be exclusive, and others not so, under the same form of
expression, from the nature of the different powers respectively; so
where the power, on any one subject, is given in general words, like the
power to regulate commerce, the true method of construction will be to
consider of what parts the grant is composed, and which of those, from
the nature of the thing, ought to be considered exclusive. The right set
up in this case, under the laws of New York, is a monopoly. Now I think
it very reasonable to say, that the Constitution never intended to leave
with the States the power of granting monopolies either of trade or of
navigation; and therefore, that, as to this, the commercial power is
exclusive in Congress.

It is in vain to look for a precise and exact _definition_ of the powers
of Congress on several subjects. The Constitution does not undertake the
task of making such exact definitions. In conferring powers, it proceeds
by the way of _enumeration_, stating the powers conferred, one after
another, in few words and where the power is general or complex in its
nature, the extent of the grant must necessarily be judged of, and
limited, by its object, and by the nature of the power.

Few things are better known than the immediate causes which led to the
adoption of the pres