An impost, or duty on imports, is a custom or a tax levied on articles brought into a country, and is most usually secured before the importer is allowed to exercise his rights of ownership over them, because evasions of the law can be prevented more certainly by executing it while the articles are in its custody. It would not, however, be less an impost or duty on the articles, if it were to be levied on them after they were landed. The policy and consequent practice of levying or securing the duty before, or on entering the port, does not limit the power to that state of things, nor, consequently, the prohibition, unless the true meaning of the clause so confines it. What, then, are "imports"? The lexicons inform us, they are "things imported." If we appeal to usage for the meaning of the word, we shall receive the same answer. They are the articles themselves which are brought into the country. "A duty on imports," then, is not merely a duty on the act of importation, but is a duty on the thing imported. It is not, taken in its literal sense, confined to a duty levied while the article is entering the country, but extends to a duty levied after it has entered the country. The succeeding words of the sentence which limit the prohibition, show the extent in which it was understood. The limitation is, "except what may be absolutely necessary for executing its inspection laws." Now, the inspection laws, so far as they act upon articles for exportation, are generally executed on land, before the article is put on board the vessel; so far as they act upon importations, they are generally executed upon articles which are landed. The tax or duty of inspection, then, is a tax which is frequently, if not always paid for service performed on land, while the article is in the bosom of the country. Yet this tax is an exception to the prohibition on the States to lay duties on imports or exports. The exception was made because the tax would otherwise have been within the prohibition. If it be a rule of interpretation to which all assent, that the exception of a particular thing from general words, proves that, in the opinion of the lawgiver, the thing excepted would be within the general clause, had the exception not been made, we know no reason why this general rule should not be as applicable to the constitution as to other instruments. If it be applicable, then, this exception in favor of duties for the support of inspection laws, goes far in proving that the framers of the constitution classed taxes of a similar character with those imposed for the purpose of inspection, with duties on imports and exports, and supposed them to be prohibited.
If we quit this narrow view of the subject, and passing from the literal interpretation of the words, look to the objects of the prohibition, we find no reason for withdrawing the act under consideration from its operation. From the vast inequality between the different states of the Confederacy, as to commercial advantages, few subjects were viewed with deeper interest, or excited more irritation, than the manner in which the several States exercised, or seemed disposed to exercise, the power of laying duties on imports. From motives which were deemed sufficient by the statesmen of that day, the general power of taxation, indispensably necessary as it was, and jealous as the States were of any encroachment on it, was so far abridged as to forbid them to touch imports or exports, with the single exception which has been noticed. Why are they restrained from imposing these duties? Plainly, because, in the general opinion, the interest of all would be best promoted by placing that whole subject under the control of Congress. Whether the prohibition to "lay imposts,