On the other hand, it has been repeatedly held that the States may, in the absence of legislation by Congress, enact quarantine laws, even though in effect they thereby regulate foreign commerce; and furthermore that such legislation may be, in the interest of effective enforcement, applied beyond the mere exclusion of diseased persons. Thus in the leading case the State of Louisiana was sustained in authorizing its Board of Health in its discretion to prohibit the introduction into any infected portion of the State of "persons acclimated, unacclimated or said to be immune, when in its judgment the introduction of such persons would add to or increase the prevalence of the disease."[779] At the same time it was emphasized that all such legislation was subject to be supplanted by Congress at any time.
STATE GAME PROTECTION AND FOREIGN COMMERCE
The Court's tolerance of legal provisions which might not standing alone be constitutional, when they are designed to make legislation within the police power practically enforceable, is also illustrated in connection with State game laws. In the case of Silz v. Hesterberg[780] the Court was confronted with a New York statute establishing a closed season for certain game, during which season it was a penal offense to take or possess any of the protected animals, fish or birds; and providing farther that the ban should equally apply "to such fish, game or flesh coming from without the State as to that taken within the State." This provision was held to have been validly applied in the case of a dealer in imported game who had in his possession during the closed season "one dead body of an imported grouse, ..., and taken in Russia." Again the absence of conflicting legislation by Congress was adverted to.[781]
The Police Power and Interstate Commerce
GENERAL PRINCIPLES
In Southern Pacific Co. v. Arizona,[782] decided in 1945, Chief Justice Stone made the following systematic statement of principles which have guided the Court in the exercise of its power of judicial review of State legislation affecting interstate commerce: "Although the commerce clause conferred on the national government power to regulate commerce, its possession of the power does not exclude all state power of regulation. Ever since Willson v. Black-Bird Creek Marsh Co., 2 Pet. 245, and Cooley v. Board of Wardens, 12 How. 299, it has been recognized that, in the absence of conflicting legislation by Congress, there is a residuum of power in the state to make laws governing matters of local concern which nevertheless in some measure affect interstate commerce or even, to some extent, regulate it.[783] Thus the states may regulate matters which, because of their number and diversity, may never be adequately dealt with by Congress.[784] When the regulation of matters of local concern is local in character and effect, and its impact on the national commerce does not seriously interfere with its operation, and the consequent incentive to deal with them nationally is slight, such regulation has been generally held to be within state authority.[785]
"But ever since Gibbons v. Ogden, 9 Wheat. 1, the states have not been deemed to have authority to impede substantially the free flow of commerce from state to state, or to regulate those phases of the national commerce which, because of the need of national uniformity, demand that their regulation, if any, be prescribed by a single authority.[786] Whether or not this long-recognized distribution of power between the national and the state governments is predicated upon the implications of the commerce clause itself,[787] or upon the presumed intention of Congress, where Congress has not spoken,[788] the result is the same.
"In the application of these principles some enactments may be found to be plainly within and others plainly without state power. But between these extremes lies the infinite variety of cases, in which regulation of local matters may also operate as a regulation of commerce, in which reconciliation of the conflicting claims of state and national power is to be attained only by some appraisal and accommodation of the competing demands of the state and national interests involved.[789]
"For a hundred years it has been accepted constitutional doctrine that the commerce clause, without the aid of Congressional legislation, thus affords some protection from state legislation inimical to the national commerce, and that in such cases, where Congress has not acted, this Court, and not the state legislature, is under the commerce clause the final arbiter of the competing demands of state and national interests.[790]