Mr. Justice BRENNAN:

This civil action was brought to redress the alleged deprivation of federal constitutional rights. The complaint, alleging that by means of a 1901 statute of Tennessee apportioning the members of the General Assembly among the state's 95 counties, "these plaintiffs and others similarly situated, are denied the equal protection of the laws accorded them by the Fourteenth Amendment to the Constitution of the United States by virtue of the debasement of their votes," was dismissed by a three-judge court in the Middle District of Tennessee. The court held that it lacked jurisdiction of the subject matter and also that no claim was stated upon which relief could be granted. We hold that the dismissal was error, and remand the cause to the District Court for trial and further proceedings consistent with this opinion....

The Tennessee Constitution provides in Article II as follows:

"SEC. 4. Census. —An enumeration of the qualified voters, and an ax portionment of the Representatives in the General Assembly, shall be made in the year one thousand eight hundred and seventy-one, and within every subsequent term of ten years.

"SEC. 5. Apportionment of representatives. —The number of Representatives shall, at the several periods of making the enumeration, be apportioned among the several counties or districts, according to the number of qualified voters in each....

"SEC. 6. Apportionment of senators. —The number of Senators shall, at the several periods of making the enumeration, be apportioned among the several counties or districts according to the number of qualified electors in each, and shall not exceed one-third in the number of representatives. . . ."

Thus, Tennessee's standard for allocating legislative representation among her counties the total number of qualified voters resident in the respective counties, subject only to minor qualifications. Decennial reapportionment in compliance with the constitutional scheme was effected by the General Assembly each decade from 1871 to 1901....

I In the more than 60 years since that Action, all proposals in both Houses of the General Assembly for reapportionment have failed to pass.

Between 1901 and 190l, Tennessee has experienced substantial growth and redistribution of her population. In 1901, the population was 2,020,616, of whom 487,380 were eligible to vote. The 1960 federal census reports the State's population at 3,567,089, of whom 2,092,891 are eligible to vote. The relative standings of the counties in terms of qualified voters have changed significantly. It is primarily the continued application of the 1901 Apportionment Act to this shifted and enlarged voting population which gives rise to the present controversy.

Indeed, the complaint alleges that the 1901 statute, even as of the time of its passage, "made no apportionment of Representatives and Senators in accordance with Our constitutional formula . . ., but instead arbitrarily and capriciously apportioned representatives in the Senate and House without reference . .. to any logical or reasonable formula whatever." It is further Alleged that "because of the population Changes since 1900, and the failure of the legislature to reapportion itself since 1901,"

The 1901 statute became "unconstitutional and obsolete. " Appellants also argue that, because of the composition of the legislature effected by the 1901 apportionment act, redress in the form of a state constitutional amendment to change the entire mechanism for reapportioning, or any other change short of that, is difficult or impossible. The complaint concludes that "these plaintiffs and others similarly situated, are denied the equal protection of the laws accorded them by the Fourteenth Amendment to the Constitution of the United States by virtue of the debasement of their votes." They seek a declaration that the 1901 statute is unconstitutional and an injunction restraining the appellees from acting to conduct any further elections under it. They also pray that unless and until the General Assembly enacts a valid reapportionment, the District Court should either decree a reapportionment by mathematical application of the Tennessee constitutional formulae to the most recent federal census figures, or direct the appellees to conduct legislative elections, primary and general, at large. They also pray for such other and further relief as may be appropriate....

In light of the District Court's treatment of the case, we hold today only (a) that the court possessed jurisdiction of the subject matter; (b) that a justifiable cause of action is stated upon which appellants would be entitled to appropriate relief; and (c) because appellees raise the issue before this Court, that the appellants have standing to challenge the Tennessee apportionment statutes. Beyond noting that we have no cause at this stage to doubt the District Court will be able to fashion relief if violations of constitutional rights are found, it is improper now to consider what remedy would be most appropriate if appellants prevail at the trial....

Article III, Sect. 2 of the federal Constitution provides that "the judicial Power shall extend to all Cases, in Law and Equity, arising under this Constitution, the Laws of the United States, and Treaties made, or which shall be made, under their Authority; . .." It is clear that the cause of action is one which "arises under" the federal Constitution. The complaint alleges that the 1901 statute effects an apportionment that deprives the appellants of the equal protection of the laws in violation of the Fourteenth Amendment. Dismissal of the complaint upon the ground of lack of jurisdiction of the subject matter would, therefore, be justified only if that claim were "so attenuated and unsubstantial as to be absolutely devoid of merit." . . .

Since the complaint plainly sets forth a case arising under the Constitution, the subject matter is within the federal judicial power defined in Art. III, Sect. 2, and so within the power of Congress to assign to the jurisdiction of the District Courts. Congress has exercised that power.

An unbroken line of our precedents sustains the federal courts' jurisdiction of the subject matter of federal constitutional claims of this nature.

A federal court cannot "pronounce any statute, either of a state or of the United States, void, because irreconcilable with the Constitution, except as it is called upon to adjudge the legal rights of litigants in actual controversies. "

Have the appellants alleged such a personal stake in the outcome of the controversy as to assure that concrete adverseness which sharpens the presentation of issues upon which the court so largely depends for illumination of difficult constitutional questions? This is the gist of the question of standing. It is, of course, a question of federal law....

We hold that the appellants do have tanding to maintain this suit. Our decisions Plainly support this conclusion. Many of the cases have assumed rather than articulated The premise in deciding the merits of similar claims. And Colegrove v. Green, squarely held that voters who allege facts showing disadvantage to themselves as individuals ave standing to sue. A number of cases decided after Colegrove recognized the standng of the voters there involved to bring hose actions.

These appellants seek relief in order to protect or vindicate an interest of their own, nd of those similarly situated. Their constitutional claim is, in substance, that the 1901 statute constitutes arbitrary and capricious state action, offensive to the Fourteenth amendment in its irrational disregard of the standard of apportionment prescribed by the State's constitution or of any standard, effecting a gross disproportion of representation to voting population.... A citizen's right to a vote free of arbitrary impairment by state action has been judicially recognized as a right secured by the Constitution, when such impairment resulted from dilution by a false tally, cf. United States v. Classic, 313 U. S. 299, or by a refusal to count votes from arbitrarily selected precincts, cf. United States v. Mosley, 238 U. S. 383, or by a stuffing of the ballot box cf. Ex parte Siebold, 100 U. S. 371.

It would not be necessary to decide whether appellants' allegations of impairment of their votes by the 1901 apportionment will, ultimately, entitle them to any relief, in order to hold that they have standing to seek it. If such impairment does produce a legally cognizable injury, they are among those who have sustained it. They are asserting "a plain, direct and adequate interest in maintaining the effectiveness of their votes," Coleman v. Miller, 307 U. S. at 438. They are entitled to a hearing and to the District Court's decision on their claims. "The very essence of civil liberty certainly consists in the right of every individual to claim the protection of the laws, whenever he receives an injury." Marbury v. Madison, 5 U. S. 137,163.

In . .. Colegrove v. Green, the court stated: "From a review of these decisions there can be no doubt that the federal rule . .. is that the federal courts . .. will not intervene in cases of this type to compel legislative reapportionment." 179 F. Supp. at 826. We understand the District Court to have read the cited cases as compelling the conclusion that since the appellants sought to have a legislative apportionment held unconstitutional, their suit presented a "political question" and was therefore nonjusticiable. We hold that this challenge to an apportionment presents no nonjusticiable "political question." The cited cases do not hold the contrary. Of course the mere fact that the suit seeks protection of a political right does not mean it presents a political question....

But it is argued that this case shares the characteristics of decisions that constitute a category not yet considered, cases concerning the Constitution's guaranty, in Art. IV, Sect. 4, of a republican form of government. A conclusion as to whether the case at bar does present a political question cannot be, confidently reached until we have considered F those cases with special care. We shall discover that Guaranty Clause claims involve those elements which define a "political question," and for that reason and no other, they are nonjusticiable. In particular, we shall discover that the nonjusticiability of such claims has nothing to do with their touching upon matters of state governmental organization....

We come, finally, to the ultimate inquiry whether our precedents as to what constitutes a nonjusticiable 'political question" bring the case before us under the umbrella of that doctrine. A natural beginning is to note whether any of the common characteristics which we have been able to identify and label descriptively are present. We find none: The question here is the consistency of state action with the federal Constitution. We have no question decided, or to be decided, by a political branch of government coequal with this Court. Nor do we risk embarrassment of our government abroad, or grave disturbance at home if we take issue with Tennessee as to the constitutionality of her action here challenged. Nor need the appellants, in order to succeed in this action, ask the Court to enter upon policy determinations for which judicially manageable standards are lacking. Judicial standards under the Equal Protection Clause are well developed and familiar, and it has been open to courts since the enactment of the Fourteenth Amendment to determine, if on the I particular facts they must, that a discrimination reflects no policy, but simply arbitrary and capricious action.

This case does, in one sense, involve the allocation of political power within a state, and the appellants might conceivably have added a claim under the Guaranty Clause. Of course, as we have seen, any reliance on that clause would be futile. Both because any reliance on the Guaranty Clause could not have succeeded it does not follow that appellants may not be heard on the Equal Protection claim which in fact they tender. True, it must be clear that the Fourteenth Amendment claim is not so enmeshed with those political question elements which render Guaranty Clause claims nonjusticiable as actually to present a political question itself. But we have found that not to be the case here....

We conclude that the complaint's allegations of a denial of equal protection present a justifiable constitutional cause of action upon which appellants are entitled to a trial and a decision. The right asserted is within the reach of judicial protection under the Fourteenth Amendment.

The judgment of the District Court is reversed....

Justices DOUGLAS, CLARK, and STEWART filed concurring opinions. FRANKFURTER and HARLAN dissented.