dissenting.
The majority opinion appears to concede, as I think it should, that the Compact Clause reaches interstate agree*480ments presenting even potential encroachments on federal supremacy. In applying its Compact Clause theory to the circumstances of the Multistate Tax Compact, however, the majority is not true to this view. For if the Compact Clause has any independent protective force at all, it must require the consent of Congress to an interstate scheme of such complexity and detail as this. The majority states it will *481watch for the mere potential of harm to federal interests, but then approves the Compact here for lack of actual proved harm.
I
The Constitution incorporates many restrictions on the powers of individual States. Some of these are explicit, some are inferred from positive delegations of power to the Federal Government. In the latter category falls the federal authority over interstate commerce.1 The individual States have long been permitted to legislate, in a nondiscriminatory manner, over matters affecting interstate commerce, where Congress has not exerted its authority, and where the federal interest does not require a uniform rule. Cooley v. Board of Wardens, 12 How. 299 (1852); Southern Pacific Co. v. Arizona ex rel. Sullivan, 325 U. S. 761 (1945).
It is not denied by any party to this case that the apportionment of revenues, sales, and income of multistate and multinational corporations for taxation purposes is an area over which the Congress could exert authority, ousting the efforts of any States in the field. To date, however, the Federal Government has taken only limited steps in this context.2 No federal legislation has been enacted, nor tax treaties ratified, that would interfere with any State’s efforts to apply uniform apportionment rules, unitary business concepts, or single multistate audits of corporations. Hence, leaving to one side appellants’ contentions that these matters inherently require uniform federal treatment, there is no *482obstacle in the Commerce Clause to such action by an individual State.
The Compact Clause, however, is directed to joint action by more than one State. If its only purpose in the present context were to require the consent of Congress to agreements between States that would otherwise violate the Commerce Clause, it would have no independent meaning. The Clause must mean that some actions which would be permissible for individual States to undertake are not permissible for a group of States to agree to undertake.
There is much history from the Articles of Confederation to support that conclusion.3 In framing the Constitution the *483new Republic was at pains to correct the divisive factors of the Government under the Articles; and among the most important of these were “compacts witht. the consent of Congs. as between Pena, and N. Jersey, and between Virga. & Maryd.” James Madison, “Preface to Debates in the Convention of 1787,” 3 M. Farrand, Records of the Federal Convention of 1787, p. 548 (1937). A compact between two States necessarily achieved some object unattainable, or attainable less conveniently, by separate States acting alone. Such effects were jealously guarded against, lest “the Fedl authy [be] violated.” Ibid. It was the Federal Government’s province to oversee conduct of a greater effect than a single State could accomplish, to protect both its own prerogative and that of the excluded States.4
Compacts and agreements between States were put in a separate constitutional category, and purposefully so. Nor is the form used by the agreeing States important; as the majority correctly observes:
“Agreements effected through reciprocal legislation may present opportunities for enhancement of state power *484at the expense of the federal supremacy similar to the threats inherent in a more formalized ‘compact.’. . . The Clause reaches both ‘agreements’ and ‘compacts,’ the formal as well as the informal. The relevant inquiry must be one of impact on our federal structure.” Ante, at 470-471 (footnotes omitted).
“Appellants further urge that the pertinent inquiry is one of potential, rather than actual, impact upon federal supremacy. We agree.” Ante, at 472.
This is an apt recognition of the important distinction between the Compact Clause and the Commerce Clause. States may legislate in interstate commerce until an actual impact upon federal supremacy occurs. For individual States, the harm of potential impact is insufficiently upsetting to require prior congressional approval. For States acting in concert, however, whether through informal agreement, reciprocal legislation, or formal compact, “potential . . . impact upon federal supremacy” is enough to invoke the requirement of congressional approval.5
To this point, my views do not diverge from those of the majority as I understand them. But we do differ markedly in the application of those views to the Multistate Tax Compact.
II
Congressional consent to an interstate compact may be expressed in-several ways. In the leading case of Virginia v. Tennessee, 148 U. S. 503 (1893), congressional consent to a compact setting a boundary was inferred from years of acqui*485escence to that line by the Congress in delimiting federal judicial and electoral districts. Id., at 522. Congressional consent may also be given in advance of the adoption of any specific compacts, by general consent resolutions, as was the case for the highway safety compacts, 72 Stat. 635, and the Crime Control Compact Consent Act of 1934, ch. 406, 48 Stat. 909.
Congress does not pass upon a submitted compact in the manner of a court of law deciding a question of constitutionality. Rather, the requirement that Congress approve a compact is to obtain its political judgment:6 Is the agreement likely to interfere with federal activity in the area, is it likely to disadvantage other States to an important extent, is it a matter that would better be left untouched by state and federal regulation? 7 It comports with the purpose of seeking the political consent Congress affords that such consent may be expressed in ways as informal as tacit recognition8 or prior approval, that Congress be permitted to attach condi*486tions upon its consent,9 and that congressional approval be a continuing requirement.10
In the present case, it would not be possible to infer approval from the congressional reaction to the Multistate Tax Compact. Indeed, the history of the Congress and the Compact is a chronicle of jealous attempts of one to close out the efforts of the other.11
On the congressional side of this long-lived battle, bills to approve the Compact have been introduced 12 separate times,12 but all have faltered before arriving at a vote. Congress took the first step in the field of interstate tax apportionment with Pub. L. No. 86-272, 73 Stat. 555, passed the same year that this Court’s opinion in Northwestern States Portland Cement Co. v. Minnesota, 358 U. S. 450 (1959), *487approved state taxation of reasonably identified multistate corporate income. A special subcommittee (the Willis Committee) was established which reported five years later with specific recommendations for federal statutory solution to the interstate allocation problem. In the Multistate Tax Commission’s own words:
“The origin and history of the Multistate Tax Compact are intimately related and bound up with the history of the states’ struggle to save their fiscal and political independence from encroachments of certain federal legislation introduced in >[C]ongress during the past three years. These were the Interstate Taxation Acts, better known as the Willis Bills.” 13
A special meeting of the National Association of Tax Administrators was called in January 1966; that gathering was the genesis of the Multistate Tax Compact. Over the course of 11 years, numerous bills have been introduced in the Congress as successors to the original Willis Bills, but none has ever become law.14
For its part, the Multistate Tax Commission has made no attempt to disguise its purpose.. In its First Annual Report, the Commission spoke proudly of “bottling up the Willis Bill [alternative federal legislation] for an extended period,” but warned that “it cannot be said that the threat of coercive, restrictive federal legislation is gone.” 1 Multistate Tax Commission Ann. Rep. 10 (1968). In the most recent annual report, the tone has not changed. The Commission lists as one of its “major goals” the desire to “guard against restrictive federal legislation and other federal action which impinges upon the ability of state tax administrators to carry out the laws of their states effectively.” 9 Multistate Tax Commission Ann. Rep. 1 (1976). The same report pledged continued *488opposition to specific bills introduced in Congress restricting the States' utilization of the unitary-business concept and providing alternatives to the Compact's recommended method of apportioning multistate corporate earnings to the various States.15 Even more importantly, the Commission denounced the tax treaty already signed with Great Britain (though not yet ratified),16 for its prohibition of the unitary-business concept, the practice whereby a State combines for tax pur-poses the incomes from several related companies belonging to a single parent, even when the business carried on in a particular State is conducted by only one of the related companies. The President has negotiated this treaty in the diplomatic interest of the United States; but acting together through their joint agency, the Multistate Tax Commission, the Compact States are opposing its ratification. Of course, the Compact States have every right, in their own interest, to petition the branches of the Federal Government. Still, it cannot be disputed that the action of over 20 States, speaking through a single, established authority, carries an influence far stronger than would 20 separate voices.
A hostile stalemate characterizes the present position of the parties: the Multistate Tax Compact States opposing the Federal Congress and, since the proposed new tax treaty, the Federal Executive as well. No one could view this history and conclude that the Congress has acquiesced in the Multistate Tax Compact.
But more is demonstrated by this long dispute underlying the present case: Not only has Congress failed to acquiesce in the Multistate Tax Compact, but both Congress and the Executive have clearly demonstrated that there is a federal interest in the rules for apportioning multistate and multinational income. The Executive cannot constitutionally express his federal sovereign interest in the matter any more *489unambiguously. He has negotiated a treaty with a foreign power and submitted that treaty to the Senate. As for the Congress, its federal sovereign interest in the topic was early established in Pub. L. No. 86-272. While the following years have produced no new legislation, the activity over the Willis Report, the Willis Bills, the successor bills, and the dozen shelvings of compact ratification bills establish at the very least that the Congress believes a federal interest is involved.17 That a potential impact on federal concerns is at stake is indisputable.
It might be argued that Congress could more clearly have expressed its federal interest by passing a statute pre-empting the field, possibly in the form of an alternative apportionment formula. To hold Congress to the necessity of such action, however, accords no force to the Compact Clause independent of the Commerce Clause, as explained above. If the way to show a “potential federal interest” requires an exercise of the actual federal commerce power, then the purposes of the Compact Clause, and the Framers’ deep-seated and special fear of agreements between States, would be accorded absolutely no respect.
Ill
Virginia v. Tennessee18 quite clearly holds that not all agreements and compacts must be submitted to the Congress. The majority’s phraseology of the test as “potential impact upon federal supremacy” incorporates the Virginia v. Tennessee standard. Nor do I disagree that many interstate agreements are legally effective without congressional consent. “Potential impact upon federal supremacy” requires some demonstration of a federal interest in the matter under consideration, and a threat to that interest. In very few cases, *490short of a direct conflict, will the record of congressional and executive action demonstrate as clearly as the record in the present case that the Federal Government considers itself to have a valid interest in the subject matter. Examples of compacts over which no federal concern was inferable have already been suggested.19
It seems to me, however, that even if a realistic potential impact on federal supremacy failed to- materialize at one historic moment, that should not mean that an interstate compact or agreement is forever immune from congressional disapproval on an absolute or conditional basis. Yet the majority’s approach appears to be that, because the instant agreement is, in the majority’s view, initially without the Clause, it will never require congressional approval. The majority would approve this Compact without congressional ratification purely on the basis of its form: that no power is conferred upon the Multistate Tax Commission that could not be independently exercised by a member State. Such a view pre-termits the possibility of requiring congressional approval in the future should circumstances later present even more clearly- a potential federal interest, so long as the form of the Compact has not changed. That consequence fails to provide the ongoing congressional oversight that is part of the Compact Clause’s protections.20
IY
For appellants’ many suggestions of extraordinary authority wielded by the Multistate Tax Commission, the majority has but one repeated answer: that each member State is free *491to adopt the procedures in question just as it could as if the Compact did not exist.
This cannot be an adequate answer even for the majority, which holds that “[ajgreements effected through reciprocal legislation may present opportunities for enhancement of state power at the expense of the federal supremacy similar to the threats inherent in a more formalized 'compact.’ ” Ante, at 470 (footnote omitted). Reciprocal legislation is adopted by each State independently, yet derives its force from the knowledge that other States are acting in identical fashion. In recognizing Compact Clause concerns even in reciprocal legislation, the majority correctly lays the premise that the absence of an autonomous authority would not be controlling.
So here, that the Compact States act in concerted fashion to foreclose federal law and treaties on apportionment of income, multistate audits, and unitary-business concepts21 tells us at the least that a potential impact on federal supremacy exists. No realistic view of that impact could maintain that it is no greater than if individual States, acting purely spontaneously and without concert, had taken the same steps. It is pure fantasy to suggest that 21 States could conceivably have arrived independently at identical regulations for apportioning income, reciprocal subpoena powers, and identical interstate audits of multinational corporations, in the absence of some agreement among them.
Further, it is not clear upon reading the majority’s opinion that appellants’ suggestions of actual synergistic powers in the Multistate Tax Commission have been adequately answered. *492The Commission does have some life of its own. Under Art. VIII, providing for interstate audits, the Commission is given authority to offer to conduct audits even if no State has made a request.
“If the Commission, on the basis of its experience, has reason to believe that an audit of a particular taxpayer, either at a particular time or on a particular schedule, would be of interest to a number of party States or their subdivisions, it may offer to make the audit or audits, the offer to be contingent on sufficient participation therein as determined by the Commission.” Multistate Tax Compact, Art. VIII, § 5.
If not for the Commission's acting on its own, in the absence of a suggestion from any State, the audit would not come about, even if the States subsequently approve. That implies some effects can be achieved beyond what the individual States themselves would have achieved, since, by hypothesis, no State would have proposed the audit on its own.
Other troubling provisions are Art. III, § 1, requiring that all member States must allow taxpayers to apportion their income in accord with Art. IV (the substance of which is similar to the Uniform Division of Income for Tax Purposes Act); and Art. III, § 2, requiring that all member States must offer a short-form option for small-business income tax.22 If Compact States have no choice in the matter, these sections unquestionably go beyond the mere advisory role in which the majority would cast the Multistate Commission.
On its face, the Compact also provides in Art. IX for compulsory arbitration of allocation disputes among the member States at the option of any taxpayer electing to apportion his *493income in accord with Art. IV. Although Art. IX is not now operative (it requires passage of a regulation by the Commission to revive the arbitration mechanism), it was in effect for two and a half years. This provision binds the member States’ participation, even against their will in any particular case. In two final respects, the Compact also differs significantly from reciprocal legislation. The subpoena power which the Compact makes possible (auditors can obtain subpoenas in any one of the States which have adopted Art. VIII of the Compact) is far different from what would be accomplished through reciprocal laws, in that it places an unusual “all-or-nothing” pressure on the non-Compact States. The usual form of reciprocal law is a statute passed by State Y, saying that any other State which accords Y access to its courts for the enforcement of tax obligations likewise will have access to the courts of Y. This Compact says that an outsider State will obtain reciprocal subpoena powers only as part of a package of Art. VIII Compact States — its own courts must be opened to all these States, and in return it will obtain Compact-wide access for judicial process needed in its own tax enforcement.
Lastly, the very creation of the Compact sets it apart from separate state action. The Compact did not become effective in any of the ratifying States until at least seven States had adopted it. Thus, unlike reciprocal legislation, the Compact provided a means by which a State could assure itself that a certain number of other States would go along before committing itself to an apportionment formula.
V
One aspect of the Virginia v. Tennessee test for congressional approval of interstate compacts requires specific emphasis. The Virginia v. Tennessee opinion speaks of whether a combination tends “to the increase of political power in the States, which may encroach upon or interfere *494with the just supremacy of the United States." 148 U. S., at 519, and later, whether a compact or agreement would “encroach or not upon the full and free exercise of Federal authority.” Id., at 520.
The majority properly notes that any agreement among the States will increase their power, and focuses on the critical question of whether such an increase will enhance “state power quoad the National Government.” Ante, at 473. A proper understanding of what would encroach upon federal authority, however, must also incorporate encroachments on the authority and power of non-Compact States.
In Rhode Island v. Massachusetts, 12 Pet. 657, 726 (1838), this Court held that the purpose of requiring the submission to Congress of a compact (in that case, regarding a boundary) between two States was “to guard against the derangement of their federal relations with the other states of the Union, and the federal government; which might be injuriously affected, if the contracting states might act upon their boundaries at their pleasure.” See also Florida v. Georgia, 17 How. 478, 494 (1855). There is no want of authority for the conclusion that encroachments upon non-compact States are as seriously to be guarded against as encroachments upon the federal authority,23 *495nor is that surprising in vie.w of the Federal Government’s pre-eminent purpose to protect the rights of one State against another. If the effect of a compact were to put non-compact States at a serious disadvantage, the federal interest would thereby be affected as well.
The majority appears to recognize that allegations of harmful impact on other States is a cognizable challenge to a compact. See ante, at 477-478, 462-463, n. 12. The response the majority opinion provides is by now a familiar one: “Each member State is free to adopt the auditing procedures it thinks best, just as it could if the Compact did not exist.” Ante, at 477-478. The criticism of this reasoning offered above, in the context of encroachment on federal power, is applicable here as well. Judging by effect, not form, it is obvious that non-Compact States can be placed at a competitive disadvantage by the Multistate Tax Compact.
One example is in the attraction of multistate corporations to locate within a certain State’s borders. Before the Multi-state Tax Compact, “nonbusiness” dividend income was most commonly allocated to the State where a corporation was domiciled.24 Under the Compact’s “advisory” regulations, this type of income is apportioned among the several States where the company conducts its business. Hence, a non-Compact State will run the risk of taxing a domiciliary multi-state corporation on more than 100% of its nonbusiness income, unless, of course, the State agrees to follow the rule of the Compact. Another way to view the impact on a nonmember State is that if it ^wished to attract a multistate *496corporation to become a domiciliary, it might offer not to tax nonbusiness income. But with such income being apportioned by several other States anyway, the lure of the domicile State's exemption is effectively dissipated.
None of these results is necessarily “bad.” The only conclusion urged here is that the effect on non-Compact States be recognized as sufficiently serious that Congress should be consulted. As the constitutional arbiter of political differences between States, the Congress is the proper body to evaluate the extent of harm being imposed on non-Compact States, and to impose ameliorative restrictions as might be necessary.
The Compact Clause is an important, intended safeguard within our constitutional structure. It is functionally a conciliatory rather than a prohibitive clause. All it requires is that Congress review interstate agreements that are capable of affecting federal or other States' rights. In the Court's decision today, a highly complex multistate compact, detailed in structure and pervasive in its effect on the important area of interstate and international business taxation, has been legitimized without the consent of Congress. If the Multi-state Tax Compact is not a compact within the meaning of Art. I, § 10, then I fear there is very little life remaining in that section of our Constitution.
I respectfully dissent.
“The Congress shall have Power ... To regulate Commerce with foreign Nations, and among the several States . . . .” U. S. Const., Art. I, §8.
Title 15 U. S. C. §§ 381-384, passed in 1959 as Pub. L. No. 86-272, 73 Stat. 555, limits the jurisdictional bases open to States whereby taxation authority may be exerted. More comprehensive federal regulation of this area has often been proposed; see ante, at 456 n. 4.
Under the Articles of Confederation, dealings of the States with foreign governments and among themselves were separately treated. Article YI of the Articles of Confederation provided:
Ҥ 1. No State, without the Consent of the United States, in Congress assembled, shall send any embassy to, or receive any embassy from, or enter into any confe [r]enee, agreement, alliance, or treaty, with any king, prince or State
Thereafter, in that same Article, it was provided:
“§ 2. No two or more States shall enter into any treaty, confederation, or alliance whatever, between them, without the consent of the United States, in Congress assembled, specifying accurately the purposes for which the same is to be entered into, and how long it shall continue.”
There was thus no requirement that mere “agreements” between States be subjected to the approval of Congress. That the framers of the Articles recognized a distinction between treaties, alliances, and confederations on the one hand and agreements on the other is demonstrated by the differing language in the two paragraphs above quoted, taken from the same Article.
David Engdahl, in Characterization of Interstate Arrangements: When is a Compact not a Compact?, 64 Mich. L. Rev. 63, 81 (1965), has suggested a perceptive rationale for this difference in treatment. Article IX, § 2, of the Articles of Confederation provided:
“The United States, in Congress assembled, shall also be the last resort on appeal in all disputes and.differences now subsisting, or that hereafter may arise between two or more States concerning boundary, jurisdiction, or any other cause whatever . .. .”
And it specified an elaborate system by which the Congress would *483constitute a court for tbe resolution of interstate disputes. Hence, if there were a disagreement over a compact that had been reached between two or more States, it could be adjudicated amicably before the Congress without risk of disrupting the Union. Treaties with foreign states, on the other hand, were much more dangerous and could embroil a State in serious obligations and even war. Of almost the same level of seriousness were alliances between the States, of potential long duration and obliging one State to treat two sister States in different fashion. For these reasons, prior approval by the Congress was required.
As Madison’s commentary quoted in the text indicates, there was dissatisfaction with the way in which the Articles of Confederation provided for interstate compacts. The Constitution adopted an absolute prohibition against treaties, alliances, or confederations by the States; and imposed the requirement of congressional approval for “any Agreement or Compact with another State, or with a foreign Power.” U. S. Const., Art. I, § 10.
See infra, at 493-496.
The frequent circumstance of potential impact would make that standard unworkable in the Commerce Clause context since the result is pre-emption of state effort; but where the result is merely the requirement that Congress be consulted about the State’s effort, as is the ease with the Compact Clause, the application of that standard is not nearly so obstructive.
See n. 3, supra.
The pioneer article in the compact literature, Frankfurter & Landis, The Compact Clause of the Constitution — A Study in Interstate Adjustments, 34 Yale L. J. 685 (1925), recognized the preferability of compacts to litigation in light of the political factors that could be balanced in the process of submitting and approving a compact. See id., at 696, 706-707. This Court has also observed the peculiar amenability of some problems to settlement by compact rather than litigation. See Colorado v. Kansas, 320 U. S. 383, 392 (1943). See also F. Zimmermann & M. Wendell, The Interstate Compact Since 1925, pp. 102-103 (1951).
A statute-of-limitations type of approach to the necessary duration, of congressional silence before consent may be inferred has been suggested by one commentator. Note, The Constitutionality of the Multistate Tax Compact, 29 Vand. L. Rev. 453, 460 (1976). The National Association of Attorneys General has also declared its support for the use of informal procedures. F. Zimmermann & M. Wendell, The Law and Use of Interstate Compacts 25 (1961).
In West Virginia ex rel. Dyer v. Sims, 341 U. S. 22, 27 (1951), this Court commented favorably on the provisions of the Compact involved which allowed continuing participation by the Federal Government through the President’s power to designate members of the supervisory commission. The Port of New York Authority Compacts of 1921 and 1922 were among the first to provide for direct continuing supervisory authority by Congress. See Celler, Congress, Compacts, and Interstate Authorities, 26 Law & Contemp. Prob. 682, 688 (1961) (hereinafter Celler). It has been suggested that the imposition of conditions and the continuing nature of Congress’ supervision are perceived as drawbacks by compacting States, and have led to a hesitancy to submit interstate agreements to Congress. See Note, supra, n. 8, at 461.
This Court has held that Congress must possess the continuing power to reconsider terms approved in compacts, lest “[C]ongress and two States . . . possess the power to modify and alter the [Constitution itself.” Pennsylvania v. Wheeling & Belmont Bridge Co., 18 How. 421, 433 (1856). See also Celler 685, and authorities cited therein.
An excellent summary of the several battles in this war is recounted in Hellerstein, State Taxation Under the Commerce Clause: An Historical Perspective, 29 Yand. L. Rev. 335, 339-342 (1976). See also Sharpe, State Taxation of Interstate Businesses and the Multistate Tax Compact: The Search for a Delicate Uniformity, 11 Colum. J. L. & Soc. Prob. 231, 240-244 (1975) (hereinafter Sharpe).
See ante, at 458 n. 8.
1 Multistate Tax Commission Ann. Rep. 1 (1968).
See ante, at 456 n. 4.
See also 7 Multistate Tax Commission Ann. Rep. 3 (1974).
See ante, at 476 n. 29.
For contrasting examples, where Congress perceived no federal interest, see Zimmermann & Wendell, supra, n. 8, at 21.
See also Wharton v. Wise, 153 U. S. 155 (1894), applying the Virginia v. Tennessee dicta.
See ante, at 471-472, n. 24 (discussion of Interstate Compact to- Conserve Oil and Gas).
See n. 10, supra. Frankfurter and Landis found great value in interstate compacts because of their “[e]ontinuous and creative administration.” See Frankfurter & Landis, supra, n. 7, at 707. By excluding Congress from the administration of the Multistate Tax Compact, the majority opinion restricts this facet of the Compact’s attractiveness.
For a detailed analysis of the complex taxation issues underlying each of these terms, see Carlson, State Taxation of Corporate Income from Foreign Sources, Department of Treasury Tax Policy Research Study Number Three, Essays in International Taxation: 1976, pp. 231, 235-252. For a thorough treatment of the income-allocation problem in the multinational setting, see Note, Multinational Corporations and Income Allocation Under Section 482 of the Internal Revenue Code, 89 Harv. L. Rev. 1202 (1976).
There is some question as to whether this Article is as mandatory as its language suggests. Several States in the Compact do not provide the option, and several others have not adopted the requisite rates to accompany the option. See Sharpe 245 n. 55. However, most of the member States have complied.
See, e. g., United States v. Tobin, 195 F. Supp. 588, 606 (DC 1961); Tribe, Intergovernmental Immunities in Litigation, Taxation, and Regulation: Separation of Powers Issues in Controversies About Federalism, 89 Harv. L. Rev. 682, 712 (1976); Sharpe 265-272 (specifically observing state complaints about the Multistate Tax Compact); Zimmermann & Wendell, supra, n. 8, at 23; Celler 684 (purpose of Compact Clause “ ‘to prevent undue injury to the interests of noncompacting states/ ” quoting United States v. Tobin, supra); and Frankfurter & Landis, supra, n. 7, at 694-695. The Frankfurter and Landis treatment is perhaps the clearest expression of how the protection of federal and noncompact state interests blend in the rationale for the Compact Clause:
“But the Constitution plainly had two very practical objectives in view in conditioning agreement by States upon consent of Congress. For only Congress is the appropriate organ for determining what arrangements between States might fall within the prohibited class of ‘Treaty, Alliance, *495or Confederation,’ and what arrangements come within the permissive class of ‘Agreement or Compact.’ But even the permissive agreements may affect the interests of States other than those parties to the agreement: the national, and not merely a regional, interest may be involved. Therefore, Congress must exercise national supervision through its power to grant or withhold consent, or to grant it under appropriate conditions.” Ibid.
See Sharpe 269.