by John Marshall Harlan

“ In the exercise of its police powers, a State may exclude from its territory, or prohibit the sale therein of any articles which, in its judgment, fairly exercised, are prejudicial to the health or which would endanger the lives or property of its people. But if the State, under the guise of exerting its police powers, should make such exclusion or prohibition applicable solely to articles, of that kind, that may be produced or manufactured in other States, the courts would find no difficulty in holding such legislation to be in conflict which the Constitution of the United States. ”

“ But it is claimed that a State may empower one of its political agencies, a mere municipal corporation representing a portion of its civil power, to burden inter-state commerce by exacting from those transporting to its wharves the products of other States wharfage fees, which it does not exact from those bringing to the same wharves the products of Maryland. The city can no more do this than it or the State could discriminate against the citizens and products of other States in the use of the public streets or other public highways. ”

“ Such exactions, in the name of wharfage, must be regarded as taxation upon inter-state commerce. Municipal corporations, owning wharves upon the public navigable waters of the United States, and quasi public corporations transporting the products of the country, cannot be permitted by discriminations of that character to impede commercial intercourse and traffic among the several States and with foreign nations. ”