the scope of the power to regulate commerce, simply, because it is a known and ordinary means of exercising the power. It is one of many, and may be used like all others according to legislative discretion. The motive to the exercise of a power can never form a constitutional objection to the exercise of the power.
§ 1086. Here, then, is a case of laying duties, an ordinary means used in executing the power to regulate commerce; how can it be deemed unconstitutional? If it be said, that the motive is not to collect revenue, what has that to do with the power? When an act is constitutional, as an exercise of a power, can it be unconstitutional from the motives, with which it is passed? If it can, then the constitutionality of an act must depend, not upon the power, but upon the motives of the legislature. It will follow, as a consequence, that the same act passed by one legislature will be constitutional, and by another unconstitutional. Nay, it might be unconstitutional, as well from its omissions as its enactments, since if its omissions were to favour manufactures, the motive would contaminate the whole law. Such a doctrine would be novel and absurd. It would confuse and destroy all the tests of constitutional rights and authorities. Congress could never pass any law without an inquisition into the motives of every member; and even then, they might be re-examinable. Besides; what possible means can there be of making such investigations? The motives of many of the members may be, nay must be utterly unknown, and incapable of ascertainment by any judicial or other inquiry: they may be mixed up in various manners and degrees; they may be opposite to, or wholly independent of each other. The constitution would thus depend upon processes utterly vague, and incomprehensible; and the
