delivered the opinion of the Court.
The state-operated University of Maryland grants preferential treatment for purposes of tuition and fees to students with “in-state” status. Although citizens and immigrant aliens may obtain in-state status upon a showing of domicile within the State, nonimmigrant aliens, even if domiciled, are not eligible for such status. The question in this case is whether the University’s in-state policy is invalid under the Supremacy Clause of the Constitution, insofar as the policy categorically denies in-state status to domiciled nonimmigrant aliens who hold G-4 visas.
I
The factual and procedural background of this case, which has prompted two prior decisions of this Court, requires some elaboration. The focus of the controversy has been a policy adopted by the University in 1973 governing the eligibility of students for in-state status with respect to admission and fees. The policy provides in relevant part:
“1. It is the policy of the University of Maryland to grant in-state status for admission, tuition and charge-differential purposes to United States citizens, and to immigrant aliens lawfully admitted for permanent residence in accordance with the laws of the United States, in the following cases:
*4“a. Where a student is financially dependent upon a parent, parents, or spouse domiciled in Maryland for at least six consecutive months prior to the last day available for registration for the forthcoming semester.
“b. Where a student is financially independent for at least the preceding twelve months, and provided the student has maintained his domicile in Maryland for at least six consecutive months immediately prior to the last day available for registration for the forthcoming semester.” App. to Pet. for Cert. 167a-168a.
In 1975, when this action was filed, respondents Juan Carlos Moreno, Juan Pablo Otero, and Clare B. Hogg were students at the University of Maryland. Each resided with, and was financially dependent on, a parent who was a nonimmigrant alien holding a “G-4” visa. Such visas are issued to nonimmigrant aliens who are officers or employees of certain international organizations, and to members of their immediate families. 66 Stat. 168, 8 U. S. C. § 1101(a)(15)(G)(iv).1 Despite respondents’ residence in the State, the University denied them in-state status pursuant to its policy of excluding all nonimmigrant aliens. Seeking declaratory and injunctive relief, the three respondents filed a class action against the University of Maryland and its President.2 They contended that the University’s policy violated various federal laws, the Due Process and Equal Protection Clauses of the Fourteenth Amendment, and the Supremacy Clause.
*5The District Court granted partial summary judgment in favor of the three named plaintiffs and the class of G-4 visa-holders represented by them.3 In the view of the District Court, the University’s denial of in-state status to these plaintiffs rested upon an irrebuttable presumption that a G-4 alien cannot establish Maryland domicile. Concluding that the presumption was “not universally true” as a matter of either federal or Maryland law, the District Court held that under Vlandis v. Kline, 412 U. S. 441 (1973), the in-state policy violated the Due Process Clause of the Fourteenth Amendment. Moreno v. University of Maryland, 420 F. Supp. 541, 559 (Md. 1976). Accordingly, in an order dated July 13, 1976, the District Court enjoined the President of the University4 from denying respondents the opportunity to establish in-state status solely on the basis of an “irrebuttable presumption of non-domicile.” Id., at 565.5 The court stayed its order pending appeal in reliance on the University’s representation that it would make appropriate refunds “in the event the Court’s Order of July 13, 1976, were finally affirmed on appeal.” App. to Pet. for Cert. 100a. The Court of Appeals for the Fourth Circuit affirmed, adopt*6ing the reasoning of the District Court. Id., at 102a.6 Affirmance order reported at 556 F. 2d 573 (1977).
We reviewed the case on writ of certiorari. Elkins v. Moreno, 435 U. S. 647 (1978). We held that “[b]ecause petitioner makes domicile the ‘paramount’ policy consideration and because respondents’ contention is that they can be domiciled in Maryland but are conclusively presumed to be unable to do so, this case is squarely within Vlandis as limited by [Weinberger v.] Salfi, [422 U. S. 749 (1975)].” Id., at 660.7 It was therefore necessary to decide whether the presumption was universally true. With respect to federal law, we concluded that G-4 visaholders could “adopt the United States as their domicile.” Id., at 666.8 We were thus left with the “potentially dispositive” question whether G-4 aliens are as a matter of state law incapable of becoming domiciliaries of Maryland. We certified this question to the Maryland Court of Appeals.9 The state court answered the *7certified question in the negative, advising us that “nothing in the general Maryland law of domicile renders G-4 visa holders, or their dependents, incapable of becoming domiciled in this State.” Toll v. Moreno, 284 Md. 425, 444, 397 A. 2d 1009, 1019 (1979).
After our certification, but before the state court’s response, the University adopted a “clarifying resolution” concerning its in-state policy.10 By its terms the resolution did not offer a new definition of “in-state” students; rather, it purported to “reaffirm” the existing policy.11 The resolution indicated, however, that the University’s policy, “insofar as it denies in-state status to nonimmigrant aliens, serves a number of substantial purposes and interests, whether or not it conforms to the generally or otherwise applicable definition of domicile under the Maryland common law.” App. to Pet. for Cert. 173a. The interests assertedly served by the policy were described in the following terms:
“(a) limiting the University’s expenditures by granting a higher subsidy toward the expenses of providing educational services to that class of persons who, as a class, are more likely to have a close affinity to the State and to contribute more to its economic well-being;
“(b) achieving equalization between the affected classes of the expenses of providing educational services;
“(c) efficiently administering the University’s in-state determination and appeals process; and
*8“(d) preventing disparate treatment among categories of nonimmigrants with respect to admissions, tuition, and charge-differentials.” Id., at 173a-174a.
Following the Maryland Court of Appeals’ decision, the case returned to this Court. But we declined to restore the case to the active docket for full briefing and argument, concluding that the University’s clarifying resolution had “fundamentally altered the posture of the case.” Toll v. Moreno, 441 U. S. 458, 461 (1979) (per curiam). We noted that “if domicile [was] not the ‘paramount’ policy consideration of the University, this case [was] no longer ‘squarely within Vlandis as limited by Salfi,’” and thus raised “new issues of constitutional law which should be addressed in the first instance by the District Court.” Id., at 461-462, quoting Elkins v. Moreno, supra, at 660.12 Accordingly, we vacated the judgment of the Court of Appeals and remanded the case “to the District Court for further consideration in light of our opinion and judgment in Elkins, the opinion and judgment of the Maryland Court of Appeals in Toll, and the Board of Regents’ clarifying resolution of June 23, 1978.” 441 U. S., at 462.
On remand, the District Court determined that the clarifying resolution constituted a change in the University’s position. Before that resolution, the University’s primary concern had in fact been domicile; after the resolution, domicile was no longer “the paramount consideration in the University’s policy.” 480 F. Supp. 1116, 1124 (Md. 1979). Thus, *9with respect to the period preceding the issuance of the resolution, the District Court reaffirmed its earlier determination that insofar as the policy precluded G-4 aliens (or their dependents) from acquiring in-state status, it denied due process under Vlandis. 480 F. Supp., at 1122-1125. With respect to the period following the promulgation of the resolution, however, the court held that Vlandis did not control: The University had abandoned its position that G-4 aliens could not establish domicile in Maryland. 480 F. Supp., at 1125. Nevertheless, the District Court concluded that the revised in-state policy was constitutionally invalid, basing its conclusion on two alternative grounds. First, the court held that the policy ran afoul of the Equal Protection Clause of the Fourteenth Amendment. According to the court, the challenged portion of the University’s policy contained a classification based on alienage, requiring strict scrutiny, an analysis which the policy did not, survive, since the policy did not further any compelling interest. 489 F. Supp. 658, 660-667 (Md. 1980). Alternatively, the court held that the in-state policy violated the Supremacy Clause by encroaching upon Congress’ prerogatives with respect to the regulation of immigration. Id., at 667-668.13
The Court of Appeals affirmed for “reasons sufficiently stated” by the District Court. Moreno v. University of Maryland, 645 F. 2d 217, 220 (1981) (per curiam). We granted certiorari. 454 U. S. 815 (1981). For the reasons that follow, we hold that the University of Maryland’s instate policy, as applied to G-4 aliens and their dependents, violates the Supremacy Clause of the Constitution,14 and on *10that ground affirm the judgment of the Court of Appeals. We therefore have no occasion to consider whether the policy violates the Due Process or Equal Protection Clauses.
II
Our cases have long recognized the preeminent role of the Federal Government with respect to the regulation of aliens within our borders. See, e. g., Mathews v. Diaz, 426 U. S. 67 (1976); Graham v. Richardson, 403 U. S. 365, 377-380 (1971); Takahashi v. Fish & Game Comm’n, 334 U. S. 410, 418-420 (1948); Hines v. Davidowitz, 312 U. S. 52, 62-68 (1941); Truax v. Raich, 239 U. S. 33, 42 (1915). Federal authority to regulate the status of aliens derives from various sources, including the Federal Government’s power “[t]o establish [a] uniform Rule of Naturalization,” U. S. Const., Art. I, § 8, cl. 4, its power “[t]o regulate Commerce with foreign Nations”, id., cl. 3, and its broad authority over foreign affairs, see United States v. Curtiss-Wright Export Corp., 299 U. S. 304, 318 (1936); Mathews v. Diaz, supra, at 81, n. 17; Harisiades v. Shaughnessy, 342 U. S. 580, 588-589 (1952).
Not surprisingly, therefore, our cases have also been at pains to note the substantial limitations upon the authority of the States in making classifications based upon alienage. In Takahashi v. Fish & Game Comm’n, supra, we considered a California statute that precluded aliens who were “ineligible for citizenship under federal law” from obtaining commercial fishing licenses, even though they “met all other state requirements” and were lawful inhabitants of the State. 334 U. S., at 414.15 In seeking to defend the statute, the State *11argued that it had “simply followed the Federal Government's lead” in classifying certain persons as “ineligible for citizenship.” Id., at 418. We rejected the argument, stressing the delicate nature of the federal-state relationship in regulating aliens:
“The Federal Government has broad constitutional powers in determining what aliens shall be admitted to the United States, the period they may remain, regulation of their conduct before naturalization, and the terms and conditions of their naturalization. Under the Constitution the states are granted no such powers; they can neither add to nor take from the conditions lawfully imposed by Congress upon admission, naturalization and residence of aliens in the United States or the several states. State laws which impose discriminatory burdens upon the entrance or residence of aliens lawfully within the United States conflict with this constitutionally derived federal power to regulate immigration, and have accordingly been held invalid.” Id., at 419 (emphasis added) (citation and footnote omitted).16
*12The decision in Graham v. Richardson, supra, followed directly from Takahashi. In Graham we held that a State may not withhold welfare benefits from resident aliens “merely because of their alienage.” 403 U. S., at 378. Such discrimination, the Court concluded, would not only violate the Equal Protection Clause, but would also encroach upon federal authority over lawfully admitted aliens. In support of the latter conclusion, the Court noted that Congress had “not seen fit to impose any burden or restriction on aliens who become indigent after their entry into the United States,” id., at 377, but rather had chosen to afford “lawfully admitted resident aliens . . . the full and equal benefit of all state laws for the security of persons and property,” id., at 378. The States had thus imposed an “auxiliary burde[n] upon the entrance or residence of aliens” that was never contemplated by Congress. Id., at 379.
Read together, Takahashi and Graham stand for the broad principle17 that “state regulation not congressionally sanc*13tioned that discriminates against aliens lawfully admitted to the country is impermissible if it imposes additional burdens not contemplated by Congress.” De Canas v. Bica, 424 U. S. 351, 358, n. 6 (1976).18 To be sure, when Congress has done nothing more than permit a class of aliens to enter the country temporarily, the proper application of the principle is likely to be a matter of some dispute. But the instant case does not present such a situation, and there can be little doubt regarding the invalidity of the challenged portion of the University’s in-state policy.
The Immigration and Nationality Act of 1952, 66 Stat. 163, as amended, 8 U. S. C. § 1101 et seq. (1976 ed. and Supp. IV), represents “a comprehensive and complete code covering all aspects of admission of aliens to this country, whether for business or pleasure, or as immigrants seeking to become permanent residents.” Elkins v. Moreno, 435 U. S., at 664. The Act recognizes two basic classes of aliens, immigrant and nonimmigrant.19 With respect to the nonimmigrant class, *14the Act establishes various categories, the G-4 category among them. For many of these nonimmigrant categories, Congress has precluded the covered alien from establishing domicile in the United States. Id., at 665.20 But significantly, Congress has allowed G-4 aliens — employees of various international organizations, and their immediate families — to enter the country on terms permitting the establishment of domicile in the United States. Id., at 666. In light of Congress’ explicit decision not to bar G-4 aliens from acquiring domicile, the State’s decision to deny “instate” status to G-4 aliens, solely on account of the G-4 alien’s federal immigration status, surely amounts to an ancillary “burden not contemplated by Congress” in admitting these aliens to the United States. We need not rely, however, simply on Congress’ decision to permit the G-4 alien to establish domicile in this country; the Federal Government has also taken the additional affirmative step of conferring special tax privileges on G-4 aliens.
As a result of an array of treaties, international agreements, and federal statutes, G-4 visaholders employed by the international organizations described in 8 U. S. C. § 1101(a)(15)(G)(iv) are relieved of federal and, in many instances, state and local taxes on the salaries paid by the organizations. For example, the international agreements governing the international banks for which the parents of the named respondents are employed specifically exempt the parents from all taxes on their organizational salaries. See Articles of Agreement of the International Bank for Reconstruction and Development, Art. VII, § 9(b), 60 Stat. 1458, T. I. A. S. No. 1502 (1945) (“No tax shall be levied on or in respect of salaries and emoluments paid by the Bank to ex*15ecutive directors, alternates, officials or employees of the Bank who are not local citizens, local subjects, or other local nationals”); Agreement Establishing the Inter-American Development Bank, Art. XI, § 9(b), [1959] 10 U. S. T. 3029, 3096, T. I. A. S. No. 4397 (1959) (“No tax shall be levied on or in respect of salaries and emoluments paid by the Bank to . . . employees of the Bank who are not local citizens or other local nationals”).21 Not only have some of the specific tax exemptions contained in international agreements been incorporated into a federal statute, see 22 U. S. C. §286h, but also the International Organizations Immunities Act has explicitly afforded a federal tax exemption for those G-4 visaholders employed by international organizations for which no treaty or international agreement has provided a tax exemption for foreign employees.22 § 4(b), 59 Stat. 670, reenacted, 68A Stat. 284, as § 893 of the Internal Revenue *16Code of 1954, 26 U. S. C. §893 (“Wages, fees, or salary of any employee [except citizens of the United States and of the Republic of the Philippines] of... an international organization . . . , received as compensation for official services to such . . . international organization shall not be included in gross income and shall be exempt from [federal] taxation”).
In affording G-4 visaholders such tax exemption, the Federal Government has undoubtedly sought to benefit the employing international organizations by enabling them to pay salaries not encumbered by the full panoply of taxes, thereby lowering the organizations’ costs. See 41 Op. Atty. Gen. 170, 172-173 (1954). The tax benefits serve as an inducement for these organizations to locate significant operations in the United States. See, e. g., H. R. Rep. No. 1203, 79th Cong., 1st Sess., 2-3 (1945); S. Rep. No. 861, 79th Cong., 1st Sess., 2-3 (1945). By imposing on those G-4 aliens who are domiciled in Maryland higher tuition and fees than are imposed on other domiciliaries of the State, the University’s policy frustrates these federal policies. Petitioners’ very argument in this Court only buttresses this conclusion. One of the grounds on which petitioners have sought to justify the discriminatory burden imposed on the named respondents is that the salaries their parents receive from the international banks for which they work are exempt from Maryland income tax. Indeed, petitioners suggest that the “dollar differential ... at stake here [is] an amount roughly equivalent to the amount of state income tax an international bank parent is spared by treaty each year.” Brief for Petitioners 23 (footnote omitted). But to the extent this is indeed a justification for the University’s policy with respect to the named respondents, it is an impermissible one: The State may not recoup indirectly from respondents’ parents the taxes that the Federal Government has expressly barred the State from collecting.23
*17In sum, the Federal Government has not merely admitted G-4 aliens into the country; it has also permitted them to establish domicile and afforded significant tax exemptions on organizational salaries. In such circumstances, we cannot conclude that Congress ever contemplated that a State, in the operation of a university, might impose discriminatory tuition charges and fees solely on account of the federal immigration classification.24 We therefore conclude that insofar as it bars domiciled G-4 aliens (and their dependents) from acquiring in-state status, the University’s policy violates the Supremacy Clause.25
Ill
Finally, we must address petitioners’ contention that the Eleventh Amendment precluded the District Court from ordering the University to pay refunds to various class members who would have obtained in-state status but for the stay of the District Court’s original order of July 13,1976. As petitioners concede, in seeking a stay of that order the Univer*18sity made the representation to the District Court that in the event the 1976 order was “finally affirmed on appeal,” it would make appropriate refunds. This representation was incorporated in the stay orders of both the District Court and Court of Appeals. It is petitioners’ contention, however, that the 1976 order was “effectively” vacated when this Court, in Toll v. Moreno, 441 U. S. 458 (1979), vacated the judgment of the Court of Appeals and remanded the case to the District Court for reconsideration. Petitioners therefore conclude that the terms of the University’s waiver of sovereign immunity can no longer be satisfied.
Petitioners’ argument is not persuasive. We do not interpret Toll as having vacated the judgment of the District Court. In Toll the Court recognized that the University had altered its position through the promulgation of the clarifying resolution, raising “new issues of constitutional law which should be addressed in the first instance by the District Court.” Id,., at 462. The Court declined, however, to decide whether the District Court, in issuing its 1976 order, had improperly relied on due process grounds, and whether continuation of the order was justified on equal protection or pre-emption grounds. Thus, while we vacated “the judgment of the Court of Appeals,” ibid., we left the judgment of the District Court undisturbed.26 And contrary to petitioners’ suggestion, a vacatur of the District Court’s judgment was not necessary to give the District Court jurisdiction to reconsider the case. See Goldberg v. United States, 425 *19U. S. 94, 111-112 (1976); Campbell v. United States, 365 U. S. 85, 98-99 (1961); 28 U. S. C. §2106 (“The Supreme Court . . . may affirm, modify, vacate, set aside or reverse any judgment. . . and may. . . require such further proceedings to be had as may be just under the circumstances”).27
IV
For the foregoing reasons, the judgment of the Court of Appeals is
Affirmed.
The international organizations covered by the provision are those that are entitled to the privileges, exemptions, and immunities conferred under the International Organizations Immunities Act, 59 Stat. 669, 22 U. S. C. § 288 et seq. At the time suit was brought, the named plaintiffs in this case were dependents of employees of either the Inter-American Development Bank or the International Bank for Reconstruction and Development (World Bank).
A fourth individual, Rene Otero, Jr., a respondent in this Court, was made a named plaintiff in 1980 when a supplemental complaint was filed.
The court certified a class of G-4 visaholders or their dependents who, “residing in Maryland,. . . are current students at the University of Maryland, or . . . chose not to apply to the University of Maryland because of the challenged policies but would now be interested in attending if given an opportunity to establish ‘in-state’ status, or . . . are currently students in senior high schools in Maryland.” Moreno v. University of Maryland, 420 F. Supp. 541, 563 (Md. 1976).
Citing Monroe v. Pape, 365 U. S. 167 (1961), the District Court dismissed the claim against the University itself. 420 F. Supp., at 548-550. The plaintiffs did not appeal that dismissal.
The District Court did not order the University to grant the named plaintiffs in-state status. Rather, it merely barred the University from denying them and the members of the class “the opportunity to demonstrate that they or any of them are entitled to ‘in-state’ status for purposes of tuition and charge differential determinations.” Id., at 565.
The Court of Appeals stayed its mandate “on the same terms as the district court originally granted its stay.” App. to Pet. for Cert. 103a-104a.
Salfi limited Vlandis “to those situations in which a State ‘purports] to be concerned with [domicile, but] at the same time denfies] to one seeking to meet its test of [domicile] the opportunity to show factors clearly bearing on that issue.’ ” Elkins v. Moreno, 435 U. S., at 660, quoting Weinberger v. Salfi, 422 U. S. 749, 771 (1975).
We noted that as to some categories of nonimmigrant aliens, Congress had “expressly conditioned admission... on an intent not to abandon a foreign residence or, by implication, on an intent not to seek domicile in the United States.” 435 U. S., at 665. See, e. g., 8 U. S. C. §§ 1101(a)(15) (B), (F), (H). With respect to G-4 nonimmigrant aliens, however, we concluded that Congress had deliberately declined to “impose restrictions on intent,” thereby permitting them to “adopt the United States as their domicile.” 435 U. S., at 666.
The certified question was phrased as follows:
“Are persons residing in Maryland who hold or are named in a visa under 8 U. S. C. § 1101(a)(15)(G)(iv) (1976 ed.), or who are financially dependent upon a person holding or named in such a visa, incapable as a matter of state law of becoming domiciliaries of Maryland?” Id., at 668-669 (footnote omitted).
It was entitled “A Resolution Clarifying the Purposes, Meaning, and Application of the Policy of the University of Maryland for Determination of In-State Status for Admission, Tuition, and Charge-Differential Purposes, Insofar as It Denies In-State Status to Nonimmigrant Aliens.” App. to Pet. for Cert. 172a.
“Reaffirmation of In-State Policy. Regardless of whether or not the policy approved by the Board of Regents on September 21, 1973, conforms with the generally or otherwise applicable definition of domicile under the Maryland common law, the Board of Regents reaffirms that policy . . . .” Id., at 174a.
We further noted:
“Our decision in Elkins rests on the premise that ‘the University apparently has no interest in continuing to deny in-state status to G-4 aliens as a class if they can become Maryland domiciliaries since it has indicated both here and in the District Court that it would redraft its policy “to accommodate” G-4 aliens were the Maryland courts to hold that G-4 aliens can’ acquire such domicile. 435 U. S., at 661. After the clarifying resolution, this premise no longer appears to be true.” 441 U. S., at 461.
The District Court’s pre-emption holding rested in part on its equal protection analysis; according to the court, “the standard utilized to uphold a state regulation dealing with benefits to be accorded to aliens is essentially the strict scrutiny analysis” of equal protection. 489 F. Supp., at 668.
“This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, *10under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.” Art. VI, cl. 2.
At the time Takahashi was decided, federal law “permitted Japanese and certain other non-white racial groups to enter and reside in the coun*11try, but . . . made them ineligible for United States citizenship.” 334 U. S., at 412 (footnote omitted).
Justice Rehnquist, in dissent, suggests that the italicized language should not be interpreted literally. Post, at 28-29. Rather, he suggests, the language can only be understood as explaining three prior Court cases that Takahashi cited in a footnote immediately after the italicized language. 334 U. S., at 419, n. 6, citing Truax v. Raich, 239 U. S. 33 (1915), Chy Lung v. Freeman, 92 U. S. 275, 280 (1876), and Hines v. Davidowitz, 312 U. S. 52, 65-68 (1941). According to Justice Rehnquist, “in each of these cases, the Court found either a clear encroachment on exclusive federal power to admit aliens into the country or a clear conflict with a specific congressional purpose.” Post, at 29. Justice Rehnquist thus concludes that the language in Takahashi does not mean what it says; instead it means that absent a clear encroachment on exclusive federal power or clear conflict with a federal statute, the States are free to treat aliens as they will. Justice Rehnquist is wrong. If the language were read in the manner suggested by the dissent, it would fail to explain Takahashi *12itself: The California statute at issue in Takahashi, denying certain lawful aliens the right to obtain commercial fishing licenses from the State, presented neither “a clear encroachment on exclusive federal power to admit aliens” nor “a clear conflict with a specific congressional purpose.” Justice RehnquiSt’s wowliteral interpretation of the Takahashi holding is simply wishful thinking on his part.
While pre-emption played a significant role in the Court’s analysis in Takahashi, the actual basis for invalidation of the California statute was apparently the Equal Protection Clause of the Constitution. Commentators have noted, however, that many of the Court’s decisions concerning alienage classifications, such as Takahashi, are better explained in preemption than in equal protection terms. See, e. g., Perry, Modern Equal Protection: A Conceptualization and Appraisal, 79 Colum. L. Rev. 1023, 1060-1065 (1979); Note, The Equal Treatment of Aliens: Preemption or Equal Protection?, 31 Stan. L. Rev. 1069 (1979).
Our cases do recognize, however, that a State, in the course of defining its political community, may, in appropriate circumstances, limit the participation of noncitizens in the States’ political and governmental functions. See, e. g., Cabell v. Chavez-Salido, 454 U. S. 432 (1982); Ambach v. Norwick, 441 U. S. 68, 72-75 (1979); Foley v. Connelie, 435 U. S. 291, 295-296 (1978); Sugarman v. Dougall, 413 U. S. 634, 646-649 (1973).
In De Canas, we considered whether a California statute making it unlawful in some circumstances to employ illegal aliens was invalid under the Supremacy Clause. We upheld the statute. Justice Rehnquist’s dissent in the present case suggests that the pre-emption claim was rejected in De Canas because “the Court found no strong evidence that Congress intended to pre-empt” the State’s action. Post, at 31. Justice Rehn-QUIST has misread De Canas. We rejected the pre-emption claim not because of an absence of congressional intent to pre-empt, but because Congress intended that the States be allowed, “to the extent consistent with federal law, [to] regulate the employment of illegal aliens.” 424 U. S., at 361.
Immigrant aliens are subject to stricter qualitative tests than nonimmigrant aliens. See E. Harper, Immigration Laws of the United States 228 (3d ed. 1975). And whereas there are no quantitative restrictions on the admission of nonimmigrant aliens, there are, with a few exceptions, quota limitations for immigrant aliens. See 8 U. S. C. § 1151(a) (1976 ed., Supp. IV); Harper, supra, at 228. As we noted in Elkins v. Moreno:
“Congress defined nonimmigrant classes to provide for the needs of international diplomacy, tourism, and commerce, each of which requires that aliens be admitted to the United States from time to time and all of which would be hampered if every alien entering the United States were subject *14to a quota and to the more strict entry conditions placed on immigrant aliens.” 435 U. S., at 665 (footnote omitted).
See, e. g., 8 U. S. C. § 1101(a)(15)(B) (temporary visitors for pleasure or business); § 1101(a)(15)(C) (aliens in transit); § 1101(a)(15)(F) (foreign students); § 1101(a)(15)(H) (temporary workers).
Among the similar agreements pertaining to other international organizations are the following: Articles of Agreement of the International Finance Corporation, Art. VI, § 9(b), [1956] 7 U. S. T. 2197, 2216, T. I. A. S. No. 3620 (1955) (“No tax shall be levied on or in respect of salaries and emoluments paid by the Corporation to . . . employees of the Corporation who are not local citizens, local subjects, or other local nationals”); Articles of Agreement of the International Development Association, Art. VIII, § 9(b), [1960] 11 U. S. T. 2284, 2306, T. I. A. S. No. 4607 (1960) (“No tax shall be levied on or in respect of salaries and emoluments paid by the Association to . . . employees of the Association who are not local citizens, local subjects, or other local nationals”); Convention on the Settlement of Investment Disputes Between States and Nationals of Other States, Art. 24, §2, [1966] 17 U. S. T. 1270, 1279, T. I. A. S. No. 6090 (1965) (“Except in the case of local nationals, no tax shall be levied ... on or in respect of salaries, expense allowances or other emoluments paid by the Centre to officials or employees of the Secretariat”); Articles of Agreement of the International Monetary Fund, Art. IX, § 9(b), 60 Stat. 1414, T. I. A. S. No. 1501 (1945) (“No tax shall be levied on or in respect of salaries and emoluments paid by the Fund to . . . employees of the Fund who are not local citizens, local subjects, or other local nationals”).
And by virtue of Md. Ann. Code, Art. 81, § 280(a) (1980), this group of G-4 visaholders is able to shield organizational income from Maryland income tax.
Petitioners point out that the international banks for which the named respondents’ parents work provide reimbursement for the difference be*17tween in-state and out-of-state tuition. Certainly, this fact does not assist — but undermines — petitioners’ argument. Such reimbursements only add to the employment costs of the international organizations, thereby frustrating the federal intention of benefiting the international organizations.
Some members of the class represented by the respondents derive their state tax exemption not from a treaty or international agreement, but from the combination of federal and state statutes. See supra, at 15-16, and n. 22. As to these G-4 aliens, it is true, as the dissent notes, post, at 34-35, that the Federal Government has not precluded the collection of a state income tax that is imposed on domiciliaries of the State. But even with respect to this group of G-4 aliens, the Federal Government has taken the affirmative steps of permitting the establishment of domicile and of providing federal income tax exemption on organizational salaries. This special status afforded by the Federal Government is, in our view, inconsistent with the University of Maryland’s discriminatory denial of in-state status to G-4 aliens who are domiciled in the State.
It is important to note that this case does not involve, and we express no views regarding, a State’s imposition of a burden on all individuals sharing a common relevant characteristic, of whom only some are aliens.
Petitioners note, however, that whereas the District Court’s 1976 order was based solely on due process grounds, the District Court, on remand, held the in-state policy as it operated during the period following the clarifying resolution invalid on two different grounds — equal protection and pre-emption. In our view, this fact is of little moment. Just as a respondent is entitled to defend in this Court a judgment on grounds diffeient from those relied on by the court below, e. g., Colautti v. Franklin, 439 U. S. 379, 397, n. 16 (1979), respondents in this case were entitled, following our remand, to support a reaffirmance of the earlier order on grounds previously urged but not relied on.
Even if we were to assume that the judgment of the District Court was indeed vacated, we could not say that the terms of the University’s waiver of sovereign immunity — that the District Court’s order be “finally affirmed on appeal” — would not be satisfied. Petitioners have not prevailed on the merits in a single court, despite the numerous decisions that this litigation has prompted. By its original order, the District Court held that the University’s in-state policy was invalid insofar as it discriminated against G-4 aliens. Today, we reaffirm that conclusion.