Justice Woodbury, in his opinion, agreed with Justices McLean and Grier that the laws in question were not regulations of foreign or interstate commerce, but maintained, with Chief-Justice Taney, that the power to regulate foreign or interstate commerce was concurrent. Justice Daniel, in his separate opinion, also agreed with Justices McLean and Grier that the laws in question were not regulations of foreign or interstate commerce. As to the question of “concurrency” or “exclusiveness,” his leaning appears to have been in favor of “concurrency,” although the opinion is not at all explicit upon this point. Of the two opinions, in which it was held that the State laws were regulations of foreign and interstate commerce, and that the power to regulate such commerce was “concurrent,” that of Taney, C.J., is far the abler. He boldly lays down the doctrine that, upon the question whether a State law is or is not a regulation of foreign or interstate commerce, the object and motive of the State are of no importance and cannot influence the decision. That the operative effect, and not the motive or aim of the law determines whether or not it is a regulation of foreign or interstate commerce. Starting from this premise, he argues successfully that quarantine laws, pilotage laws, and other similar laws, operating directly upon foreign or interstate commerce, are regulations of such commerce, and that, since it is admitted that the States may pass quarantine laws, pilotage laws, etc., it follows that they possess concurrent powers of regulating foreign and interstate commerce.
Granting the learned Chief-Justice his premise, his reasoning is unanswerable. The difficulty is with his premise, which is directly opposed to the doctrine so clearly brought out in Gibbons v. Ogden, that the intention or purpose, and not the operative effect, of a law determines whether or not it is a regulation of foreign or interstate commerce. He makes an elaborate attempt to explain that case. He admits that “one or two passages in that opinion (in Gibbons v. Ogden), taken by themselves, and detached from the context, would seem to countenance this doctrine” (of the exclusive power of Congress), but maintains that these passages were in answer to the argument of counsel for equal “concurrent” powers in the State and Federal governments, and were merely intended to meet that argument, and not to deny to the States “concurrent powers” subordinate to the paramount power of Congress, whenever Congress should see fit to exercise that power. He