opinion: MINNESOTA v. CLOVER LEAF CREAMERY CO. et al.
  No. 79-1171.
  Argued November 3, 1980
  Decided January 21, 1981
  BrenNAN, J., delivered the opinion of the Court, in which Burger, C. J., and Stewart, White, Marshall, and Blackmun, JJ., joined. Powell, J., filed an opinion concurring in part and dissenting in part, post, p. 474. Stevens, J., filed a dissenting opinion, post, p. 477. Rehnquist, J., took no part in the consideration or decision of the case.
  Kenneth E. Raschke, Jr., Assistant Attorney General of Minnesota, argued the cause for petitioner. With him on the briefs were Warren Spannaus, Attorney General, Richard B. Allyn, Chief Deputy Attorney General, and D. Douglas Blanke, Special Assistant Attorney General.
  Leonard J. Keyes argued the cause for respondents. With him on the brief were Douglas L. Skor and Andrea M. Bond.
  Harlon L. Dalton argued the cause for the United States as amicus curiae urging reversal. On the brief were Solicitor General McCree, Assistant Attorney General Moorman, Deputy Solicitor General Claiborne, Harriet S. Shapiro, Jacques B. Gelin, and Anne H. Shields.
  Stephen J. Snyder filed a brief for the Sierra Club as amicus curiae urging reversal.
  Briefs of amici curiae urging affirmance were filed by C. Lee Cook, Jr., John C. Berghoff, Jr., and Stephanie W. Kanwit for the Can Manufacturers Institute et al.; by John M. Cannon for the Mid-America Legal Foundation; and by Michael L. Flanagan for the Minnesota Dairies Federation.
  Justice Brennan
  delivered the opinion of the Court:
  In 1977, the Minnesota Legislature enacted a statute banning the retail sale of milk in plastic nonreturnable, nonrefillable containers, but permitting such sale in other nonreturnable, nonrefillable containers, such as paperboard milk cartons. 1977 Minn. Laws, ch. 268, Minn. Stat. § 116F.21 (1978). Respondents contend that the statute violates the Equal Protection and Commerce Clauses of the Constitution.
  I
  The purpose of the Minnesota statute is set out as § 1:
  “The legislature finds that the use of nonreturnable, nonrefillable containers for the packaging of milk and other milk products presents a solid waste management problem for the state, promotes energy waste, and depletes natural resources. The legislature therefore, in furtherance of the policies stated in Minnesota Statutes, Section 116F.01,[] determines that the use of nonreturnable, nonrefillable containers for packaging milk and other milk products should be discouraged and that the use of returnable and reusable packaging for these products is preferred and should be encouraged.” 1977 Minn. Laws, ch. 268, § 1, codified as Minn. Stat. § 116F.21 (1978).
  Section 2 of the Act forbids the retail sale of milk and fluid milk products, other than sour cream, cottage cheese, and yogurt, in nonreturnable, nonrefillable rigid or semirigid containers composed at least 50% of plastic.
  The Act was introduced with the support of the state Pollution Control Agency, Department of Natural Resources, Department of Agriculture, Consumer Services Division, and Energy Agency, and debated vigorously in both houses of the state legislature. Proponents of the legislation argued that it would promote resource conservation, ease solid waste disposal problems, and conserve energy. Relying on the results of studies and other information, they stressed the need to stop introduction of the plastic nonreturnable container before it became entrenched in the market. Opponents of the Act, also presenting empirical evidence, argued that the Act would not promote the goals asserted by the proponents, but would merely increase costs of retail milk products and prolong the use of ecologically undesirable paperboard milk cartons.
  After the Act was passed, respondents filed suit in Minnesota District Court, seeking to enjoin its enforcement. The court conducted extensive evidentiary hearings into the Act’s probable consequences, and found the evidence “in sharp conflict.” App. A-25. Nevertheless, finding itself “as fact-finder . . . obliged to weigh and evaluate this evidence,” ibid., the court resolved the evidentiary conflicts in favor of respondents, and concluded that the Act “will not succeed in effecting the Legislature’s published policy goals . . . .” Id., at A-21. The court further found that, contrary to the statement of purpose in § 1, the “actual basis” for the Act “was to promote the economic interests of certain segments of the' local dairy and pulpwood industries at the expense of the economic interests of other segments of the dairy industry and the plastics industry.” Id., at A-19. The court therefore declared the Act “null, void, and unenforceable” and enjoined its enforcement, basing the judgment on substantive due process under the Fourteenth Amendment to the United States Constitution and Art. 1, § 7, of the Minnesota Constitution; equal protection under the Fourteenth Amendment; and prohibition of unreasonable burdens on interstate commerce under Art. I, § 8, of the United States Constitution. App. A-23.
  The State appealed to the Supreme Court of Minnesota, which affirmed the District Court on the federal equal protection and due process grounds, without reaching the Commerce Clause or state-law issues. 289 N. W. 2d 79 (1979). Unlike the District Court, the State Supreme Court found that the purpose of the Act was “to promote the state in terests of encouraging the reuse and. recycling of materials and reducing the amount and type of material entering the solid waste stream,” and acknowledged the legitimacy of this purpose. Id., at 82. Nevertheless, relying on the District Court’s findings of fact, the full record, and an independent review of documentary sources, the State Supreme Court held that “the evidence conclusively demonstrates that the discrimination against plastic nonrefillables is not rationally related to the Act’s objectives.” Ibid. We granted certiorari, 445 U. S. 949, and now reverse.
  II
  The parties agree that the standard of review applicable to this case under the Equal Protection Clause is the familiar “rational basis” test. See Vance v. Bradley, 440 U. S. 93, 97 (1979); New Orleans v. Dukes, 427 U. S. 297, 303 (1976). Moreover, they agree that the purposes of the Act cited by the legislature — promoting resource conservation, easing solid waste disposal problems, and conserving energy— are legitimate state purposes. Thus, the controversy in this case centers on the narrow issue whether the legislative classification between plastic and nonplastic nonreturnable milk containers is rationally related to achievement of the statutory purposes.
  A
  Respondents apparently have not challenged the theoretical connection between a ban on plastic nonreturnables and the purposes articulated by the legislature; instead, they have argued that there is no empirical connection between the two. They produced impressive supporting evidence at trial to prove that the probable consequences of the ban on plastic nonreturnable milk containers will be to deplete natural resources, exacerbate solid waste disposal problems, and waste energy, because consumers unable to purchase milk in plastic containers will turn to paperboard milk cartons, allegedly a more environmentally harmful product.
  But' States are not required to convince the courts of the correctness of their legislative judgments. Rather, “those challenging the legislative judgment must convince the court that the legislative facts on which the classification is apparently based could not reasonably be conceived to be true by the governmental decisionmaker.” Vance v. Bradley, 440 U. S., at 111. See also Day-Brite Lighting, Inc. v. Missouri, 342 U. S. 421, 425 (1952); Henderson Co. v. Thompson, 300 U. S. 258, 264-265 (1937).
  Although parties challenging legislation under the Equal Protection Clause may introduce evidence supporting their claim that it is irrational, United States v. Carolene Products Co., 304 U. S. 144, 153-154 (1938), they cannot prevail so long as “it is evident from all the considerations presented to [the legislature], and those of which we may take judicial notice, that the question is at least debatable.” Id., at 154. Where there was evidence before the legislature reasonably supporting the classification, litigants may not procure invalidation of the legislation merely by tendering evidence in court that the legislature was mistaken.
  The District Court candidly admitted that the evidence was “in sharp conflict,” App. A-25, but resolved the conflict in favor of respondents and struck down the statute. The Supreme Court of Minnesota, however, did not reverse on the basis of this patent violation of the principles governing rationality analysis under the Equal Protection Clause. Rather, the court analyzed the statute afresh under the Equal Protection Clause, and reached the conclusion that the statute is constitutionally invalid. The State contends that in this analysis the court impermissibly substituted its judgment for that of the legislature. We turn now to that argument.
  B
  The State identifies four reasons why the classification between plastic and nonplastic nonreturnables is rationally related to the articulated statutory purposes. If any one of the four substantiates the State’s claim, we must reverse the Minnesota Supreme Court and sustain the Act.
  First, the State argues that elimination of the popular plastic milk jug will encourage the use of environmentally superior containers. There is no serious doubt that the plastic containers consume energy resources and require solid waste disposal, nor that refillable bottles and plastic pouches are environmentally superior. Citing evidence that the plastic jug is the most popular, and the gallon paperboard carton the most cumbersome and least well regarded package in the industry, the State argues that the ban on plastic nonreturnables will buy time during which environmentally preferable alternatives may be further developed and promoted.
  As Senator Spear argued during the Senate debate:
  “[T]his bill is designed to prevent the beginning of another system of non-returnables that is going to be very, very difficult [to stop] once it begins. It is true that our alternative now is not a returnable system in terms of milk bottles. Hopefully we are eventually going to be able to move to that kind of a system, but we are never going to move to a returnable system so long as we allow another non-returnable system with all the investment and all of the vested interest that that is going to involve to begin.” Transcript of the Full Senate Floor Discussion of H. F. 45, p. 6 (May 20, 1977), reprinted as Plaintiffs’ Exhibit J.
  Accord, id., at 1-2 (statement of Sen. Luther).
  The Minnesota Supreme Court dismissed this asserted state interest as “speculative and illusory.” 289 N. W. 2d, at 86. The court expressed doubt that the Minnesota Legislature or Pollution Control Agency would take any further steps to promote environmentally sound milk packaging, and stated that there is no evidence that paperboard cartons will cease to be used in Minnesota. Ibid.
  We find the State’s approach fully supportable under our precedents. This Court has made clear that a legislature need not “strike at all evils at the same time or in the same way,” Semler v. Oregon State Board of Dental Examiners, 294 U. S. 608, 610 (1935), and that a legislature “may implement [its] program step by step, . . . adopting regulations that only partially ameliorate a perceived evil and deferring complete elimination of the evil to future regulations.” New Orleans v. Dukes, 427 U. S., at 303. See also Katzenbach v. Morgan, 384 U. S. 641, 657 (1966); Williamson v. Lee Optical Co., 348 U. S. 483, 489 (1955); Railway Express Agency, Inc. v. New York, 336 U. S. 106, 110 (1949). The Equal Protection Clause does not deny the State of Minnesota the authority to ban one type of milk container conceded to cause environmental problems, merely because another type, already established in the market, is permitted to continue in use. Whether in fact the Act will promote more environmentally desirable milk packaging is not the question: the Equal Protection Clause is satisfied by our conclusion that the Minnesota Legislature could rationally have decided that its ban on plastic nonreturnable milk jugs might foster greater use of environmentally desirable alternatives.
  Second, the State argues that its ban on plastic nonreturnable milk containers will reduce the economic dislocation foreseen from the movement toward greater use of environmentally superior containers. The State notes that plastic nonreturnables have only recently been introduced on a wide scale in Minnesota, and that, at the time the legislature was considering the Act, many Minnesota dairies were preparing to invest large amounts of capital in plastic container production. As Representative Munger, chief sponsor of the bill in the House of Representatives, explained:
  “Minnesota’s dairy market is on the verge of making a major change over from essentially a paperboard container system to a system of primarily single use, throwaway plastic bottles. The major dairies in our state have ordered the blow-mold equipment to manufacture in plant the non-returnable plastic milk bottle. Members of the House, I feel now is an ideal time for this legislation when only one dairy in our state is firmly established in manufacturing and marketing the throwaway plastic milk bottle.” Transcript of the Debate of the Minnesota House of Representatives on H. F. 45, p. 2 (Mar. 10, 1977), reprinted as Plaintiffs’ Exhibit J.
  See also Transcript of the Full Senate Floor Discussion on H. F. 45, p. 6 (May 20, 1977), reprinted as Plaintiffs’ Exhibit J (statement of Sen. Milton); id., at 9 (statement of Sen. Schaaf); id., at 10-11 (statement of Sen. Perpich).
  Moreover, the State explains, to ban both the plastic and the paperboard nonreturnable milk container at once would cause an enormous disruption in the milk industry because few dairies are now able to package their products in refillable bottles or plastic pouches. Thus, by banning the plastic container while continuing to permit the paperboard container, the State was able to prevent the industry from becoming reliant on the new container, while avoiding severe economic dislocation.
  The Minnesota Supreme Court did not directly address this justification, but we find it supported by our precedents as well. In New Orleans v. Dukes, supra, we upheld a city regulation banning pushcart food vendors, but exempting from the ban two vendors who had operated in the city for over eight years. Noting that the “city could reasonably decide that newer businesses were less likely to have built up substantial reliance interests in continued operation,” we held that the city “could rationally choose initially to eliminate vendors of more recent vintage.” Id., at 305. Accord, United States v. Maryland Savings-Share Ins. Cory., 400 U. S. 4, 6 (1970). This case is not significantly different. The state legislature concluded that nonreturnable, nonrefillable milk containers pose environmental hazards, and decided to ban the most recent entry into the field. The fact that the legislature in effect “grandfathered” paperboard containers, at least temporarily, does not make the Act’s ban on plastic nonreturnables arbitrary or irrational.
  Third, the State argues that the Act will help to conserve energy. It points out that plastic milk jugs are made from plastic resin, an oil and natural gas derivative, whereas paperboard milk cartons are primarily composed of pulpwood, which is a renewable resource. This point was stressed by the Act’s proponents in the legislature. Senator Luther commented: “We have been through an energy crisis in Minnesota. We know what it is like to go without and what we are looking at here is a total blatant waste of petroleum and natural gas . . . .” Transcript of the Pull Senate Floor Discussion on H. F. 45, p. 12 (May 20, 1977), reprinted as Plaintiffs’ Exhibit J. Representative Munger said in a similar vein:
  “A sweep to the plastic throwaway bottle in the gallon size container alone would use enough additional natural gas and petroleum to heat 3,100 homes each year in Minnesota when compared to a refillable system and 1,400 compared to the present paperboard system. Plastic containers are made from a non-renewable resource while the paperboard is made from Minnesota’s forest products.” Transcript of the Debate of the Minnesota House of Representatives on H. F. 45, p. 2 (Mar. 10, 1977), reprinted as Plaintiffs’ Exhibit J.
  The Minnesota Supreme Court held, in effect, that the legislature misunderstood the facts. The court admitted that the results of a reliable study support the legislature’s conclusion that less energy is consumed in the production of paperboard containers than in the production of plastic nonreturnables, but, after crediting the contrary testimony of respondents’ expert witness and altering certain factual assumptions, the court concluded that “production of plastic nonrefillables requires less energy than production of paper containers.” 289 N. W. 2d, at 85.
  The Minnesota Supreme Court may be correct that the Act is not a sensible means of conserving energy. But we reiterate that “it is up to legislatures, not courts, to decide on the wisdom and utility of legislation.” Ferguson v. Skrupa, 372 U. S. 726, 729 (1963). Since in view of the evidence before the legislature, the question clearly is “at least debatable,” United States v. Carotene Products Co., 304 U. S., at 154, the Minnesota Supreme Court erred in substituting its judgment for that of the legislature.
  Fourth, the State argues that the Act will ease the State’s solid waste disposal problem. Most solid consumer wastes in Minnesota are disposed of in landfills. A reputable study before the Minnesota Legislature indicated that plastic milk jugs occupy a greater volume in landfills than other nonreturnable milk containers. This was one of the legislature’s major concerns. For example, in introducing the bill to the House of Representatives, Representative Munger asked rhe-torieally: “Why do we need this legislation?” Part of his answer to the query was that “the plastic non-refillable containers will increase the problems of solid waste in our state.” Transcript of the Debate of the Minnesota House of Representatives on H. F. 45, p. 1 (Mar. 10, 1977), reprinted as Plaintiffs’ Exhibit J.
  The Minnesota Supreme Court found that plastic milk jugs in fact take up less space in landfills and present fewer solid waste disposal problems than do paperboard containers. 289 N. W. 2d, at 82-85. But its ruling on this point must be rejected for the same reason we rejected its ruling concerning energy conservation: it is not the function of the courts to substitute their evaluation of legislative facts for that of the legislature.
  We therefore conclude that the ban on plastic nonreturnable milk containers bears a rational relation to the State’s objectives, and must be sustained under the Equal Protection Clause.
  Ill
  The District Court also held that the Minnesota statute is unconstitutional under the Commerce Clause because it imposes an unreasonable burden on interstate commerce. We cannot agree.
  When legislating in areas of legitimate local concern, such as environmental protection and resource conservation, States are nonetheless limited by the Commerce Clause. See Lewis v. BT Investment Managers, Inc., 447 U. S. 27, 36 (1980); Hunt v. Washington Apple Advertising Comm’n, 432 U. S. 333, 350 (1977); Southern Pacific Co. v. Arizona ex rel. Sullivan, 325 U. S. 761, 767 (1945). If a state law purporting to promote environmental purposes is in reality “simple economic protectionism,” we have applied a “virtually per se rule of invalidity.” Philadelphia v. New Jersey, 437 U. S. 617, 624 (1978). Even if a statute regulates “evenhandedly,” and imposes only “incidental” burdens on interstate commerce, the courts must nevertheless strike it down if “the burden imposed on such commerce is clearly excessive in relation to the putative local benefits.” Pike v. Bruce Church, Inc., 397 U. S. 137, 142 (1970). Moreover, “the extent of the burden that will be tolerated will of course depend on the nature of the local interest involved, and on whether it could be promoted as well with a lesser impact on interstate activities.” Ibid.
  Minnesota’s statute does not effect “simple protectionism,” but “regulates evenhandedly” by prohibiting all milk retailers from selling their products in plastic, nonreturnable milk containers, without regard to whether the milk, the containers, or the sellers are from outside the State. This statute is therefore unlike statutes discriminating against interstate commerce, which we have consistently struck down. E. g., Lewis v. BT Investment Managers, Inc., supra (Florida statutory scheme prohibiting investment advisory services by bank holding companies with principal offices out of the State); Hughes v. Oklahoma, 441 U. S. 322 (1979) (Oklahoma statute prohibiting the export of natural minnows from the State); Philadelphia v. New Jersey, supra (New Jersey statute prohibiting importation of solid and liquid wastes into the State); Hunt v. Washington Apple Advertising Gomm’n, supra (North Carolina statute imposing additional costs on Washington, but not on North Carolina, apple shippers).
  Since the statute does not discriminate between interstate and intrastate commerce, the controlling question is whether the incidental burden imposed on interstate commerce by the Minnesota Act is “clearly excessive in relation to the putative local benefits.” Pike v. Bruce Church, Inc., supra, at 142. We conclude that it is not.
  The burden imposed on interstate commerce by the statute is relatively minor. Milk products may continue to move freely across the Minnesota border, and since most dairies package their products in more than one type of containers, the inconvenience of having to conform to different packaging requirements in Minnesota and the surrounding States should be slight. See Pacific States Box & Basket Co. v. White, 296 U. S. 176, 184 (1935). Within Minnesota, business will presumably shift from manufacturers of plastic nonreturnable containers to producers of paperboard cartons, refillable bot-ties, and plastic pouches, but there is no reason to suspect that the gainers will be Minnesota firms, or the losers out-of-state firms. Indeed, two of the three dairies, the sole milk retailer, and the sole milk container producer challenging the statute in this litigation are Minnesota firms.
  Pulpwood producers are the only Minnesota industry likely to benefit significantly from the Act at the expense of out-of-state firms. Respondents point out that plastic resin, the raw material used for making plastic nonreturnable milk jugs, is produced entirely by non-Minnesota firms, while pulpwood, used for making paperboard, is a major Minnesota product. Nevertheless, it is clear that respondents exaggerate the degree of burden on out-of-state interests, both because plastics will continue to be used in the production of plastic pouches, plastic returnable bottles, and paperboard itself, and because out-of-state pulpwood producers will presumably absorb some of the business generated by the Act.
  Even granting that the out-of-state plastics industry is burdened relatively more heavily than the Minnesota pulpwood industry, we find that this burden is not “clearly excessive” in light of the substantial state interest in promoting conservation of energy and other natural resources and easing solid waste disposal problems, which we have already reviewed in the context of equal protection analysis. See supra, at 465-470. We find these local benefits ample to support Minnesota’s decision under the Commerce Clause. Moreover, we find that no approach with “a lesser impact on interstate activities,” Pike v. Bruce Church, Inc., supra, at 142, is available. Respondents have suggested several alternative statutory schemes, but these alternatives are either more burdensome on commerce than the Act (as, for example, banning all nonreturnables) or less likely to be effective (as, for example, providing incentives for recycling). See Brief for Respondents 32-33.
  In Exxon Corp. v. Governor of Maryland, 437 U. S. 117 (1978), we upheld a Maryland statute barring producers and refiners of petroleum products — all of which were out-of-state businesses — from retailing gasoline in the State. We stressed that the Commerce Clause “protects the interstate market, not particular interstate firms, from prohibitive or burdensome regulations.” Id., at 127-128. A nondiscriminatory regulation serving substantial state purposes is not invalid simply because it causes some business to shift from a predominantly out-of-state industry to a predominantly in-state industry. Only if the burden on interstate commerce clearly outweighs the State’s legitimate purposes does such a regulation violate the Commerce Clause.
  The judgment of the Minnesota Supreme Court is
  Reversed.
  Justice Rehnquist took no part in the consideration or decision of this case.
  Respondents, plaintiffs below, are a Minnesota dairy that owns equipment for producing plastic nonreturnable milk jugs, a Minnesota dairy' that leases such equipment, a non-Minnesota company that manufactures such equipment, a Minnesota company that produces plastic nonreturnable milk jugs, a non-Minnesota dairy that sells milk products in Minnesota in plastic nonreturnable milk jugs, a Minnesota milk retailer, a non-Minnesota manufacturer of polyethylene resin that sells such resin in many States, including Minnesota, and a plastics industry trade association.
  Minnesota Stat. § 116F.01 (1978) provides in relevant part:
  “Statement of policy. The legislature seeks to encourage both the reduction of the amount and type of material entering the solid waste stream and the reuse and recycling of materials. Solid waste represents discarded materials and energy resources, and it also represents an economic burden to the people of the state. The recycling of solid waste materials is one alternative for the conservation of material and energy resources, but it is also in the public interest to reduce the amount of materials requiring recycling or disposal.”
  Minnesota is apparently the first State so to regulate milk containers. 289 N. W. 2d 79, 81, n. 6 (1979).
  Transcript of the Debate of the Minnesota House of Representatives on H. F. 45, p. 1 (Mar. 10, 1977), reprinted as Plaintiffs’ Exhibit J.
  The principal empirical study cited in legislative debate, see, e. g., Transcript of the Full Senate Floor Discussion on H. F. 45, p. 12 (May 20, 1977), reprinted as Plaintiffs’ Exhibit J (statement of Sen. Luther), is Midwest Research Institute, Resource and Environmental Profile Analysis of Five Milk Container Systems, admitted into evidence as Plaintiffs’ Exhibit I.
  Justice Stevens’ dissenting opinion argues that the Minnesota Supreme Court when reviewing a challenge to a Minnesota statute on equal protection grounds is not bound by the limits applicable to federal courts, but may independently reach conclusions contrary to those of the legislature concerning legislative facts bearing on the wisdom or utility of the legislation. This argument, though novel, is without merit. A state court may, of course, apply a more stringent standard of review as a matter of state law under the State’s equivalent to the Equal Protection or Due Process Clauses. E. g., Baker v. City of Fairbanks, 471 P. 2d 386, 401-402 (Alaska 1970); Serrano v. Priest, 18 Cal. 3d 728, 76A-765, 557 P. 2d 929, 950-951 (1976), cert. denied, 432 U. S. 907 (1977); State v. Kaluna, 55 Haw. 361, 368-369, 520 P. 2d 51, 58-59 (1974); see Brennan, State Constitutions and the Protection of Individual Rights, 90 Harv. L. Rev. 489 (1977). And as the dissent correctly notes, post, at 479-481, the States are free to allocate the lawmaking function to whatever branch of state government they may choose. Uphaus v. Wyman, 360 U. S. 72, 77 (1959); Sweezy v. New Hampshire, 354 U. S. 234, 256-257 (1957) (Frankfurter, J., concurring in result); Dreyer v. Illinois, 187 U. S. 71, 83-84 (1902). But when a state court reviews state legislation challenged as violative of the Fourteenth Amendment, it is not free to impose greater restrictions as a matter of federal constitutional law than this Court has imposed. Oregon v. Hass, 420 U S. 714, 719 (1975).
  The standard of review under equal protection rationality analysis— without regard to which branch of the state government has made the legislative judgment — is governed by federal constitutional law, and a state court’s application of that standard is fully reviewable in this Court on writ of certiorari. 28 U. S. C. § 1257 (3). Justice SteveNS concedes the flaw in his argument when he admits that “a state court’s decision invalidating state legislation on federal constitutional grounds may be reversed by this Court if the state court misinterpreted the relevant federal constitutional standard.” Post, at 489. And contrary to his argument that today’s judgment finds “no precedent in this Court’s decisions,” post, at 482, we have frequently reversed State Supreme Court decisions invalidating state statutes or local ordinances on the basis of equal protection analysis more stringent than that sanctioned by this Court. E. g., Idaho Dept. of Employment v. Smith, 434 U. S. 100 (1977); Arlington County Board v. Richards, 434 U. S. 5 (1977); Richardson v. Ramirez, 418 U. S. 24 (1974); Lehnhausen v. Lake Shore Auto Parts Co., 410 U. S. 356 (1973). See also North Dakota Pharmacy Board v. Snyder’s Drug Stores, Inc., 414 U. S. 156 (1973); Dean v. Gadsen Times Publishing Corp., 412 U. S. 543 (1973); McDaniel v. Barresi, 402 U. S. 39 (1971). Never have we suggested that our review of the judgments in such cases differs in any relevant respect because they were reached by state courts rather than federal courts.
  Indeed, Justice SteveNS has changed his own view. Previously he has stated that state-court decisions under the Fourteenth Amendment granting litigants “more protection than the Federal Constitution requires,” are in error. Idaho Dept. of Employment v. Smith, supra, at 104 (Stevens, J., dissenting in part). This is in agreement with the conclusion of one commentator:
  “In reviewing state court resolutions of federal constitutional issues, the Supreme Court has not differentiated between those decisions which sustain and those which reject claims of federal constitutional right. In both instances, once having granted review, the Court has simply determined whether the state court’s federal constitutional decision is 'correct/ meaning, in this context, whether it is the decision that the Supreme Court would independently reach.” Sager, Fair Measure: The Legal Status of Underenforced Constitutional Norms, 91 Harv. L. Bev. 1212, 1243 (1978) (footnote omitted).
  Thus, Justice SteveNs’ argument in the dissenting opinion that today’s treatment of the instant case is extraordinary and unprecedented, see post, at 482, and n. 7, is simply wrong.
  Respondents, citing the District Court’s Finding of Fact No. 12, App. A-19, also assert that the actual purpose for the Act was illegitimate: to “isolate from interstate competition the interests of certain segments of the local dairy and pulpwood industries.” Brief for Respondents 23. We accept the contrary holding of the Minnesota Supreme Court that the articulated purpose of the Act is its actual purpose. See 289 N. W. 2d, at 82. In equal protection analysis, this Court will assume that the objectives articulated by the legislature are actual purposes of the statute, unless an examination of the circumstances forces us to conclude that they “could not have been a goal of the legislation.” See Weinberger v. Wiesenfeld, 420 U. S. 636, 648, n. 16 (1975); Here, a review of the legislative history supports the Minnesota Supreme Court’s conclusion that the principal purposes of the Act were to promote conservation and ease solid waste disposal problems. The contrary evidence cited by respondents, see Brief for Respondents 29-31, is easily understood, in context, as economic defense of an Act genuinely proposed for environmental reasons. We will not invalidate a state statute under the Equal Protection Clause merely because some legislators sought to obtain votes for the measure on the basis of its beneficial side effects on state industry.
  We express no view whether the District Court could have dismissed this case on the pleadings or granted summary judgment for the State on the basis of the legislative history, without hearing respondents’ evidence. See Vance v. Bradley, 440 U. S. 93, 109-112 (1979); Baydde Fish Flour Co. v. Gentry, 297 U. S. 422 (1936).
  See n. 5, supra.
  The court adopted the higher of two possible measurements of energy consumption from paperboard production, apparently because the lower figure contemplated the use of waste products, such as sawdust, for energy production. In addition, the court substituted a lower measurement of the energy consumption from plastic nonretumable production for that used in the study. 289 N. W. 2d, at 84-85.
  This was the conclusion of the Midwest Research Institute study, see n. 5, supra. Brief for Petitioner 21.
  The District Court also held that the Act violated substantive due process, and was apparently affirmed by the State Supreme Court on this ground. Conclusion of Law No. 1, App. A-23; 289 N. W. 2d, at 87, n. 20. From our conclusion under equal protection, however, it follows a fortiori that the Act does not violate the Fourteenth Amendment’s Due Process Clause. See Exxon Corp. v. Governor of Maryland, 437 U. S. 117, 124-125 (1978); Ferguson v. Skrupa, 372 U. S. 726 (1963).
  “The Congress shall have Power ... To regulate Commerce . . . among the several States . . . .” U. S. Const., Art. I, § 8, cl. 3.
  The Minnesota Supreme Court did not reach the Commerce Clause issue. 289 N. W. 2d, at 87, n. 20. The parties and amici have fully briefed and argued the question, and because of the obvious factual connection between the rationality analysis under the Equal Protection Clause and the balancing of interests under the Commerce Clause, we will reach and decide the question. See New York City Transit Authority v. Beazer, 440 U. S. 568, 583, n. 24 (1979).
  A court may find that a state law constitutes “economic protectionism” on proof either of discriminatory effect, see Philadelphia v. New Jersey, or of discriminatory purpose, see Hunt v. Washington Apple Advertising Comm’n, 432 U. S., at 352-353. Respondents advance a “discriminatory purpose” argument, relying on a finding by the District Court that the Act’s “actual basis was to promote the economic interests of certain segments of the local dairy and pulpwood industries at the expense of the economic interests of other segments of the dairy industry and the plasties industry.” App. A-19. We have already considered and rejected this argument in the equal protection context, see n. 7, supra, and do so in this context as well.
  Respondent Wells Dairy, an Iowa firm, sells 60% of its milk in plastic nonreturnable containers, and the remainder in other types of packages, including paperboard cartons. Tr. 419, 426, 439. The Chairman of the Board of respondent Marigold Foods, Inc., a Minnesota dairy, admitted at trial that his firm would continue to sell milk in plastic nonreturnable containers in other States, despite the passage of the Act. Id., at 474.
  See n. 1, supra. The existence of major in-state interests adversely affected by the Act is a powerful safeguard against legislative abuse. South Carolina State Highway Dept. v. Barnwell Bros., Inc., 303 U. S. 177, 187 (1938).
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