Opinion of the Court

is absolutely no evidence before this Court that waste generated outside Alabama is more dangerous than waste generated in Alabama. The Court finds under the facts of this case that the only basis for the additional fee is the origin of the waste." App. to Pet. for Cert. 83a-84a. In the face of such findings, invalidity under the Commerce Clause necessarily follows, for "whatever [Alabama's] ultimate purpose, it may not be accomplished by discriminating against articles of commerce coming from outside the State unless there is some reason, apart from their origin, to treat them differently." Philadelphia v. New Jersey, 437 U. S., at 626–627; see New Energy Co., 486 U. S., at 279-280. The burden is on the State to show that "the discrimination is demonstrably justified by a valid factor unrelated to economic protectionism,"6 Wyoming v. Oklahoma, 502 U. S. 437, 454 (1992) (emphasis added), and it has not carried this burden. Cf. Fort Gratiot Sanitary Landfill, post, at 361.

Ultimately, the State's concern focuses on the volume of the waste entering the Emelle facility. Less discriminatory

6 The Alabama Supreme Court found no "economic protectionism" here, and thus purported to distinguish Philadelphia v. New Jersey, based on its conclusions that the legislature was motivated by public health and environmental concerns. 584 So. 2d 1367, 1388-1389 (1991). This narrow focus on the intended consequence of the additional fee does not conform to our precedents, for "[a] finding that state legislation constitutes 'economic protectionism' may be made on the basis of either discriminatory purpose, see Hunt v. Washington Apple Advertising Comm'n, 432 U. S. 333, 352-353 (1977), or discriminatory effect, see Philadelphia v. New Jersey, supra." Bacchus Imports, Ltd. v. Dias, 468 U. S. 263, 270 (1984). The "virtually per se rule of invalidity," Philadelphia v. New Jersey, supra, at 624, applies "not only to laws motivated solely by a desire to protect local industries from out-of-state competition, but also to laws that respond to legitimate local concerns by discriminating arbitrarily against interstate trade." Maine v. Taylor, 477 U. S. 131, 148, n. 19 (1986).

7"The risk created by hazardous waste and other similarly dangerous waste materials is proportional to the volume of such waste materials present, and may be controlled by controlling that volume." Brief for Respondents 38 (citation omitted; emphasis in original).

Opinion of the Court

alternatives, however, are available to alleviate this concern, not the least of which are a generally applicable per-ton additional fee on all hazardous waste disposed of within Alabama, cf. Commonwealth Edison Co. v. Montana, 453 U. S. 609, 619 (1981), or a per-mile tax on all vehicles transporting hazardous waste across Alabama roads, cf. American Trucking Assns., Inc. v. Scheiner, 483 U. S. 266, 286 (1987), or an evenhanded cap on the total tonnage landfilled at Emelle, see Philadelphia v. New Jersey, supra, at 626, which would curtail volume from all sources.8 To the extent Alabama's concern touches environmental conservation and the health and safety of its citizens, such concern does not vary with the point of origin of the waste, and it remains within the State's power to monitor and regulate more closely the transporta

The State asserts: "An equal fee, at any level, would necessarily fail to serve the State's purpose. An equal fee high enough to provide any significant deterrent to the importation of hazardous waste for landfilling in the State would amount to an attempt by the State to avoid its responsibility to deal with its own problems, by tending to cause in-state waste to be exported for disposal. An equal fee not so high as to amount to an attempt to force Alabama's own problems to be borne by citizens of other states would fail to provide any significant reduction in the enormous volumes of imported hazardous waste being dumped in the State. At the point where an equal fee would become effective to serve the State's purpose in protecting public health and the environment from uncontrolled volumes of imported waste, that equal fee would also become an avoidance of the State's responsibility to deal with its own waste problems." Id., at 46. These assertions are without record support and in any event do not suffice to validate plain discrimination against interstate commerce. See New Energy Co. of Ind. v. Limbach, 486 U. S. 269, 280 (1988); Hale v. Bimco Trading, Inc., 306 U. S. 375, 380 (1939): "That no Florida cement needs any inspection while all foreign cement requires inspection at a cost of fifteen cents per hundredweight is too violent an assumption to justify the discrimination here disclosed." The additional fee is certainly not a "last ditch' attempt" to meet Alabama's expressed purposes "after nondiscriminatory alternatives have proved unfeasible. It is rather a choice of the most discriminatory [tax] even though nondiscriminatory alternatives would seem likely to fulfill the State's purported legitimate local purpose more effectively." Hughes v. Oklahoma, 441 U. S. 322, 338 (1979).

Opinion of the Court

tion and disposal of all hazardous waste within its borders. Even with the possible future financial and environmental risks to be borne by Alabama, such risks likewise do not vary with the waste's State of origin in a way allowing foreign, but not local, waste to be burdened. In sum, we find the additional fee to be "an obvious effort to saddle those outside the State" with most of the burden of slowing the flow of waste into the Emelle facility. Philadelphia v. New Jersey, 437 U. S., at 629. "That legislative effort is clearly impermissible under the Commerce Clause of the Constitution." Ibid.

Our decisions regarding quarantine laws do not counsel a different conclusion.10 The Act's additional fee may not legitimately be deemed a quarantine law because Alabama permits both the generation and landfilling of hazardous

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9 The State presents no argument here, as it did below, that the additional fee makes out-of-state generators pay their "fair share" of the costs of Alabama waste disposal facilities, or that the additional fee is justified as a "compensatory tax. The trial court rejected these arguments, App. to Pet. for Cert. 88a, n. 6., finding the former foreclosed by American Trucking Assns., Inc. v. Scheiner, 483 U. S. 266, 287-289 (1987), and the latter to be factually unsupported by a requisite "substantially equivalent" tax imposed solely on in-state waste, as required by, e. g., Tyler Pipe Industries, Inc. v. Washington State Dept. of Revenue, 483 U. S. 232, 242– 244 (1987). Various amici assert that the discrimination patent in the Act's additional fee is consistent with congressional authorization. We pretermit this issue, for it was not the basis for the decision below and has not been briefed or argued by the parties here.

10 The State collects and refers to the following decisions, inter alia, as ❝quarantine cases": Clason v. Indiana, 306 U. S. 439 (1939); Mintz v. Baldwin, 289 U. S. 346 (1933); Oregon-Washington Railroad & Navigation Co. v. Washington, 270 U. S. 87 (1926); Sligh v. Kirkwood, 237 U. S. 52 (1915); Asbell v. Kansas, 209 U. S. 251 (1908); Reid v. Colorado, 187 U. S. 137 (1902); Compagnie Francaise de Navigation a Vapeur v. Louisiana Bd.

Health, 186 U. S. 380 (1902); Smith v. St. Louis & Southwestern R. Co., 181 U. S. 248 (1901); Rasmussen v. Idaho, 181 U. S. 198 (1901); Missouri, K. & T. R. Co. v. Haber, 169 U. S. 613 (1898); Bowman v. Chicago & Northwestern R. Co., 125 U. S. 465 (1888); Railroad Co. v. Husen, 95 U. S. 465 (1878).

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waste within its borders and the importation of still more hazardous waste subject to payment of the additional fee. In any event, while it is true that certain quarantine laws have not been considered forbidden protectionist measures, even though directed against out-of-state commerce, those laws "did not discriminate against interstate commerce as such, but simply prevented traffic in noxious articles, whatever their origin." Philadelphia v. New Jersey, supra, at 629.11 As the Court stated in Guy v. Baltimore, 100 U. S., at 443:

"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 with the Constitution of the United States."

See also Reid v. Colorado, 187 U. S. 137, 151 (1902); Railroad Co. v. Husen, 95 U. S. 465, 472 (1878).

11 "The hostility is to the thing itself, not to merely interstate shipments of the thing; and an undiscriminating hostility is at least nondiscriminatory. But that is not the case here. The State of Illinois is quite willing to allow the storage and even the shipment for storage of spent nuclear fuel in Illinois, provided only that its origin is intrastate." Illinois v. General Elec. Co., 683 F. 2d 206, 214 (CA7 1982), cert. denied, 461 U. S. 913 (1983); cf. Oregon-Washington Co. v. Washington, supra, at 96: Inspection followed by quarantine of hay from fields infested with weevils is "a real quarantine law, and not a mere inhibition against importation of alfalfa from a large part of the country without regard to the condition which might make its importation dangerous."

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The law struck down in Philadelphia v. New Jersey left local waste untouched, although no basis existed by which to distinguish interstate waste. But "[i]f one is inherently harmful, so is the other. Yet New Jersey has banned the former while leaving its landfill sites open to the latter." 437 U. S., at 629. Here, the additional fee applies only to interstate hazardous waste, but at all points from its entrance into Alabama until it is landfilled at the Emelle facility, every concern related to quarantine applies perforce to local hazardous waste, which pays no additional fee. For this reason, the additional fee does not survive the appropriate scrutiny applicable to discriminations against interstate commerce.

Maine v. Taylor, 477 U. S. 131 (1986), provides no additional justification. Maine there demonstrated that the outof-state baitfish were subject to parasites foreign to in-state baitfish. This difference posed a threat to the State's natural resources, and absent a less discriminatory means of protecting the environment—and none was available—the importation of baitfish could properly be banned. Id., at 140. To the contrary, the record establishes that the hazardous waste at issue in this case is the same regardless of its point of origin. As noted in Fort Gratiot Sanitary Landfill, “our conclusion would be different if the imported waste raised health or other concerns not presented by [Alabama] waste." Post, at 367. Because no unique threat is posed, and because adequate means other than overt discrimination meet Alabama's concerns, Maine v. Taylor provides the State no respite.

III

The decision of the Alabama Supreme Court is reversed, and the cause is remanded for proceedings not inconsistent with this opinion, including consideration of the appropriate relief to petitioner. See McKesson Corp. v. Division of Alcoholic Beverages and Tobacco, Fla. Dept. of Business Regu