Mr. Justice CARDOZO delivered the opinion of the Court.
G. A. F. Seelig, Inc. is engaged in business as a milk dealer in the city of New York. It buys its milk, including cream, in Fair Haven, Vt., from the Seelig Creamery Corporation, which in turn buys from the producers on the neighboring farms. The milk is transported to New York by rail in 40-quart cans; the daily shipment amounting to about 200 cans of milk and 20 cans of cream. Upon arrival in New York about 90 per cent. is sold to customers in the original cans; the buyers being chiefly hotels, restaurants, and stores. About 10 per cent. is bottled in New York, and sold to customers in bottles. The New York Milk Control Act has set up a system of minimum prices to be paid by dealers to producers. From the farms of New York the inhabitants of the so-called Metropolitan milk district, comprising the city of New York and certain neighboring communities, derive about 70 per cent. of the milk requisite for their use. To keep the system unimpaired by competition from afar, the act has a provision whereby the protective prices are extended to that part of the supply (about 30 per cent.) which comes from other states. The substance of the provision is that, so far as such a prohibition is permitted by the Constitution, there shall be no sale within the state of milk bought outside unless the price paid to the producers was one that would be lawful upon a like transaction within the state. The statute, so far as pertinent, is quoted in the margin, together with supplementary regulations by the Board of Milk Control. Seelig buys its milk from the Creamery in Vermont at prices lower than the minimum payable to producers in New York. The Commissioner of Farms and Markets refuses to license the transaction of its business unless it signs an agreement to conform to the New York statute and regulations in the sale of the imported product. This the applicant declines to do. Because of that refusal other public officers, parties to these appeals, announce a purpose to prosecute for trading without a license and to recover heavy penalties. This suit has been brought to restrain the enforcement of the act in its application to the complainant; repugnancy being charged between its provisions when so applied and limitations imposed by the Constitution of the United States....
New York has no power to project its legislation into Vermont by regulating the price to be paid in that state for milk acquired there. So much is not disputed. New York is equally without power to prohibit the introduction within her territory of milk of wholesome quality acquired in Vermont, whether at high prices or at low ones. This again is not disputed. Accepting those postulates, New York asserts her power to outlaw milk so introduced by prohibiting its sale thereafter if the price that has been paid for it to the farmers of Vermont is less than would be owing in like circumstances to farmers in New York. The importer in that view may keep his milk or drink it, but sell it he may not.
Such a power, if exerted, will set a barrier to traffic between one state and another as effective as if customs duties, equal to the price differential, had been laid upon the thing transported.... Imposts and duties upon interstate commerce are placed beyond the power of a state, without the mention of an exception, by the provision committing commerce of that order to the power of the Congress. Constitution, art. 1, 8, cl. 3. 'It is the established doctrine of this court that a state may not, in any form or under any guise, directly burden the prosecution of interstate business.' Nice distinctions have been made at times between direct and indirect burdens. They are irrelevant when the avowed purpose of the obstruction, as well as its necessary tendency, is to suppress or mitigate the consequences of competition between the states. Such an obstruction is direct by the very terms of the hypothesis. We are remainded in the opinion below that a chief occasion of the commerce clauses was 'the mutual jealousies and aggressions of the States, taking form in customs barriers and other economic retaliation.' If New York, in order to promote the economic welfare of her farmers, may guard them against competition with the cheaper prices of Vermont, the door has been opened to rivalries and reprisals that were meant to be averted by subjecting commerce between the states to the power of the nation.
The argument is pressed upon us, however, that the end to be served by the Milk Control Act is something more than the economic welfare of the farmers or of any other class or classes. The end to be served is the maintenance of a regular and adequate supply of pure and wholesome milk; the supply being put in jeopardy when the farmers of the state are unable to earn a living income. Nebbia v. New York, supra. Price security, we are told, is only a special form of sanitary security; the economic motive is secondary and subordinate; the state intervenes to make its inhabitants healthy, and not to make them rich. On that assumption we are asked to say that intervention will be upheld as a valid exercise by the state of its internal police power, though there is an incidental obstruction to commerce between one state and another. This would be to eat up the rule under the guise of an exception. Economic welfare is always related to health, for there can be no health if men are starving. Let such an exception be admitted, and all that a state will have to do in times of stress and strain is to say that its farmers and merchants and workmen must be protected against competition from without, lest they go upon the poor relief lists or perish altogether. To give entrance to that excuse would be to invite a speedy end of our national solidarity. The Constitution was framed under the dominion of a political philosophy less parochial in range. It was framed upon the theory that the peoples of the several states must sink or swim together, and that in the long run prosperity and salvation are in union and not division.
We have dwelt up to this point upon the argument of the state that economic security for farmers in the milk shed may be a means of assuring to consumers a steady supply of a food of prime necessity. There is, however, another argument which seeks to establish a relation between the well-being of the producer and the quality of the product. We are told that farmers who are underpaid will be tempted to save the expense or sanitary precautions. This temptation will affect the farmers outside New York as well as those within it. For that reason, the exclusion of milk paid for in Vermont below the New York minimum will tend, it is said, to impose a higher standard of quality and thereby promote health. We think the argument will not avail to justify impediments to commerce between the states. There is neither evidence nor presumption that the same minimum prices established by order of the board for producers in New York are necessary also for producers in Vermont. But apart from such defects of proof, the evils springing from uncared for cattle must be remedied by measures of repression more direct and certain than the creation of a parity of prices between New York and other states.... Whatever relation there may be between earnings and sanitation is too remote and indirect to justify obstructions to the normal flow of commerce in its movement between states.... The line of division between direct and indirect restraints of commerce involves in its marking a reference to considerations of degree. Even so, the borderland is wide between the restraints upheld as incidental and those attempted here.
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