opinion: SOSNA v. IOWA et al.
  No. 73-762.
  Argued October 17, 1974
  Decided January 14, 1975
  Rehnquist, J., delivered the opinion of the Court, in which Burger, C. J., and Douglas, Stewart, Blackmun, and Powell, JJ., joined. White, J., filed a dissenting opinion, post, p. 410. Marshall, J., filed a dissenting opinion, in which Brennan, J., joined, post, p. 418.
  James H. Reynolds argued the cause for appellant. With him on the briefs was Paul E. Kempter.
  Elizabeth A. Nolan, Assistant Attorney General of Iowa, argued the cause for appellees. With her on the brief were Richard C. Turner, Attorney General, and George W. Murray, Special Assistant Attorney General.
  Mr. Justice Rehnquist
  delivered the opinion of the Court.
  Appellant Carol Sosna married Michael Sosna on September 5, 1964, in Michigan. They lived together in New York between October 1967 and August 1971, after which date they separated but continued to live in New York. In August 1972, appellant moved to Iowa with her three children, and the following month she petitioned the District Court of Jackson County, Iowa, for a dissolution of her marriage. Michael Sosna, who had been personally served with notice of the action when he came to Iowa to visit his children, made a special appearance to contest the jurisdiction of the Iowa court. The Iowa court dismissed the petition for lack of jurisdiction, finding that Michael Sosna was not a resident of Iowa and appellant had not been a resident of the State of Iowa for one year preceding the filing of her petition. In so doing the Iowa court applied the provisions of Iowa Code § 598.6 (1973) requiring that the petitioner in such an action be “for the last year a resident of the state.”
  Instead of appealing this ruling to the Iowa appellate courts, appellant filed a complaint in the United States District Court for the Northern District of Iowa asserting that Iowa’s durational residency requirement for in-yoking its divorce jurisdiction violated the United States Constitution. She sought both injunctive and declaratory relief against the appellees in this case, one of which is the State of Iowa, and the other of whom is the judge of the District Court of Jackson County, Iowa, who had previously dismissed her petition.
  A three-judge court, convened pursuant to 28 U. S. C. §§ 2281, 2284, held that the Iowa durational residency requirement was constitutional. 360 F. Supp. 1182 (1973). We noted probable jurisdiction, 415 U. S. 911 (1974), and directed the parties to discuss “whether the United States District Court should have proceeded to the merits of the constitutional issue presented in light of Younger v. Harris, 401 U. S. 37 (1971) and related cases.” For reasons stated in this opinion, we decide that this case is not moot, and hold that the Iowa dura-tional residency requirement for divorce does not offend the United States Constitution.
  I
  Appellant sought certification of her suit as a class action pursuant to Fed. Rule Civ. Proc. 23 so that she might represent the “class of those residents of the State of Iowa who have resided therein for a period of less than one year and who desire to initiate actions for dissolution of marriage or legal separation, and who are barred from doing so by the one-year durational residency requirement embodied in Sections 598.6 and 598.9 of the Code of Iowa.” The parties stipulated that there were in the State of Iowa “numerous people in the same situation as plaintiff,” that joinder of those persons was impracticable, that appellant’s claims were representative of the class, and that she would fairly and adequately protect the interests of the class. See Rule 23 (a). This stipulation was approved by the District Court in a pretrial order. After the submission of briefs and proposed findings of fact and conclusions of law by the parties, the three-judge court by a divided vote upheld the constitutionality of the statute.
  While the parties may be permitted to waive non-jurisdictional defects, they may not by stipulation invoke the judicial power of the United States in litigation which does not present an actual “case or controversy,” Richardson v. Ramirez, 418 U. S. 24 (1974), and on the record before us we feel obliged to address the question of mootness before reaching the merits of appellant’s claim. At the time the judgment of the three-judge court was handed down, appellant had not yet resided in Iowa for one year, and that court was clearly presented with a case or controversy in every sense contemplated by Art. Ill of the Constitution. By the time her case reached this Court, however, appellant had long since satisfied the Iowa durational residency requirement, and Iowa Code § 598.6 (1973) no longer stood as a barrier to her attempts to secure dissolution of her marriage in the Iowa courts. This is not an unusual development in a case challenging the validity of a durational residency requirement, for in many cases appellate review will not be completed until after the plaintiff has satis- ' fied the residency requirement about which complaint was originally made.
  If appellant had sued only on her own behalf, both the fact that she now satisfies the one-year residency requirement and the fact that she has obtained a divorce elsewhere would make this case moot and require dismissal. Alton v. Alton, 207 F. 2d 667 (CA3 1953), dismissed as moot, 347 U. S. 610 (1954); SEC v. Medical Committee for Human Rights, 404 U. S. 403 (1972). But appellant brought this suit as a class action and sought to litigate the constitutionality of the durational residency requirement in a representative capacity. When the District Court certified the propriety of the class action, the class of unnamed persons described in the certification acquired a legal status separate from the interest asserted by appellant. We are of the view that this factor significantly affects the mootness determination.
  In Southern Pacific Terminal Co. v. ICC, 219 U. S. 498 (1911), where a challenged ICC order had expired, and in Moore v. Ogilvie, 394 U. S. 814 (1969), where petitioners sought to be certified as candidates in an election that had already been held, the Court expressed its concern that the defendants in those cases could be expected again to act contrary to the rights asserted by the particular named plaintiffs involved, and in each case the controversy was held not to be moot because the questions presented were “capable of repetition, yet evading review.” That situation is not presented in appellant’s case, for the durational residency requirement enforced by Iowa does not at this time bar her from the Iowa courts. Unless we were to speculate that she may move from Iowa, only to return and later seek a divorce within one year from her return, the concerns that prompted this Court’s holdings in Southern Pacific and Moore do not govern appellant’s situation. But even though appellees in this proceeding might not again enforce the Iowa durational residency requirement against appellant, it is clear that they will enforce it against those persons in the class that appellant sought to represent and that the District Court certified. In this sense the case before us is one in which state officials will undoubtedly continue to enforce the challenged statute and yet, because of the passage of time, no single challenger will remain subject to its restrictions for the period necessary to see such a lawsuit to its conclusion.
  This problem was present in Dunn v. Blumstein, 405 U. S. 330 (1972), and was there implicitly resolved in favor of the representative of the class. Respondent Blumstein brought a class action challenging the Tennessee law which barred persons from registering to vote unless, at the time of the next election, they would have resided in the State for a year and in a particular county for three months. By the time the District Court opinion was filed, Blumstein had resided in the county for the requisite three months, and the State contended that his challenge to the county requirement was moot. The District Court rejected this argument, Blumstein v. Ellington, 337 F. Supp. 323, 324-326 (MD Tenn. 1970). Although the State did not raise a mootness argument in this Court, we observed that the District Court had been correct:
  “Although appellee now can vote, the problem to voters posed by the Tennessee residence requirements is ' “capable of repetition, yet evading review.” ’ ” 405 XJ. S., at 333 n. 2.
  Although the Court did not expressly note the fact, by the time it decided the case Blumstein had resided in Tennessee for far more than a year.
  The rationale of Dunn controls the present case. Although the controversy is no longer live as to appellant Sosna, it remains very much alive for the class of persons she has been certified to represent. Like the other voters in Dunn, new residents of Iowa are aggrieved by an allegedly unconstitutional statute enforced by state officials. We believe that a case such as this, in which, as in Dunn, the issue sought to be litigated escapes full appellate review at the behest of any single challenger, does not inexorably become moot by the intervening resolution of the controversy as to the named plaintiffs. Dunn, supra; Rosario v. Rockefeller, 410 U. S. 752, 756 n. 5 (1973); Vaughan v. Bower, 313 F. Supp. 37, 40 (Ariz.), aff’d, 400 U. S. 884 (1970). We note, however, that the same exigency that justifies this doctrine serves . o identify its limits. In cases in which the alleged harm would not dissipate during the normal time required for resolution of the controversy, the general principles of Art. Ill jurisdiction require that the plaintiff's personal stake in the litigation continue throughout the entirety of the litigation.
  Our conclusion that this case is not moot in no way detracts from the firmly established requirement that the judicial power of Art. Ill courts extends only to “cases and controversies” specified in that Article. There must not only be a named plaintiff who has such a case or controversy at the time the complaint is filed, and at the time the class action is certified by the District Court pursuant to Rule 23, but there must be a live controversy at the time this Court reviews the case. SEC v. Medical Committee for Human Rights, supra. The controversy may exist, however, between a named defendant and a member of the class represented by the named plaintiff, even though the claim of the named plaintiff has become moot.
  In so holding, we disturb no principles established by our decisions with respect to class-action litigation. A named plaintiff in a class action must show that the threat of injury in a case such as this is “real and immediate,” not “conjectural” or “hypothetical.” O’Shea v. Littleton, 414 U. S. 488, 494 (1974); Golden v. Zwickler, 394 U. S. 103, 109-110 (1969). A litigant must be a member of the class which he or she seeks to represent at the time the class action is certified by the district court. Bailey v. Patterson, 369 U. S. 31 (1962); Rosario, supra; Hall v. Beals, 396 U. S. 45 (1969). Appellant Sosna satisfied these criteria.
  This conclusion does not automatically establish that appellant is entitled to litigate the interests of the class she seeks to represent, but it does shift the focus of examination from the elements of justiciability to the ability of the named representative to “fairly and adequately protect the interests of the class.” Rule 23 (a). Since it is contemplated that all members of the class will be bound by the ultimate ruling on the merits, Rule 23 (c)(3), the district court must assure itself that the named representative will adequately protect the interests of the class. In the present suit, where it is unlikely that segments of the class appellant represents would have interests conflicting with those she has sought to advance, and where the interests of that class have been competently urged at each level of the proceeding, we believe that the test of Rule 23 (a) is met. We therefore address ourselves to the merits of appellant’s constitutional claim.
  II
  The durational residency requirement under attack in this case is a part of Iowa's comprehensive statutory regulation of domestic relations, an area that has long been regarded as a virtually exclusive province of the States. Cases decided by this Court over a period of more than a century bear witness to this historical fact. In Barber v. Barber, 21 How. 582, 584 (1859), the Court said: “We disclaim altogether any jurisdiction in the courts of the United States upon the subject of divorce . . . .” In Pennoyer v. Neff, 95 U. S. 714, 734-735 (1878), the Court said: “The State . . . has absolute right to prescribe the conditions upon which the marriage relation between its own citizens shall be created, and the causes for which it may be dissolved,” and the same view was reaffirmed in Simms v. Simms, 175 U. S. 162, 167. (1899).
  The statutory scheme in Iowa, like those in other States, sets forth in considerable detail the grounds upon which a marriage may be dissolved and the circumstances in which a divorce may be obtained. Jurisdiction over a petition for dissolution is established by statute in “the county where either party resides,” Iowa Code § 598.2 (1973), and the Iowa courts have construed the term . “resident” to have much the same meaning as is ordinarily associated with the concept of domicile. Korsrud v. Korsrud, 242 Iowa 178, 45 N. W. 2d 848 (1951). Iowa has recently revised its divorce statutes, incorporating the no-fault concept, but it retained the one-year dura-tional residency requirement.
  The imposition of a durational residency requirement for divorce is scarcely unique to Iowa, since 48 States impose such a requirement as a condition for maintaining an action for divorce. As might be expected, the periods vary among the States and range from six weeks to two years. The one-year period selected by Iowa is the most common length of time prescribed.
  Appellant contends that the Iowa requirement of one year’s residence is unconstitutional for two separate reasons: first, because it establishes two classes of persons and discriminates against those who have recently exercised their right to travel to Iowa, thereby contravening the Court’s holdings in Shapiro v. Thompson, 394 U. S. 618 (1969); Dunn v. Blumstein, 405 U. S. 330 (1972); and Memorial Hospital v. Maricopa County, 415 U. S. 250 (1974); and, second, because it denies a litigant the opportunity to make an individualized showing of bona fide residence and therefore denies such residents access to the only method of legally dissolving their marriage. Vlandis v. Kline, 412 U. S. 441 (1973); Boddie v. Connecticut, 401 U. S. 371 (1971).
  State statutes imposing durational residency requirements were, of course, invalidated when imposed by States as a qualification for welfare payments, Shapiro, supra; for voting, Dunn, supra; and for medical care, Maricopa County, supra. But none of those cases intimated that the States might never impose durational residency requirements, and such a proposition was in fact expressly disclaimed. What those cases had in common was that the durational residency requirements they struck down were justified on the basis of budgetary or recordkeeping considerations which were held insufficient to outweigh the constitutional claims of the individuals. But Iowa’s divorce residency requirement is of a different stripe. Appellant was not irretrievably foreclosed from obtaining some part of what she sought, as was the case with the welfare recipients in Shapiro, the voters in Dunn, or the indigent patient in Maricopa County. She would eventually qualify for the same sort of adjudication which she demanded virtually upon her arrival in the State. Iowa’s requirement delayed her access to the courts, but, by fulfilling it, she could ultimately have obtained the same opportunity for adjudication which she asserts ought to have been hers at an earlier point in time.
  Iowa’s residency requirement may reasonably be justified on grounds other than purely budgetary considerations or administrative convenience. Cf. Kahn v. Shevin, 416 U. S. 351 (1974). A decree of divorce is not a matter in which the only interested parties are the State as a sort of “grantor,” and a divorce petitioner such as appellant in the role of “grantee.” Both spouses are obviously interested in the proceedings, since it will affect their marital status and very likely their property rights. Where a married couple has minor children, a decree of divorce would usually include provisions for their custody and support. With consequences of such moment riding on a divorce decree issued by its courts, Iowa may insist that one seeking to initiate such a proceeding have the modicum of attachment to the State required here.
  Such a requirement additionally furthers the State’s parallel interests both in avoiding officious intermeddling in matters in which another State has a paramount interest, and in minimizing the susceptibility of its own divorce decrees to collateral attack. A State such as Iowa may quite reasonably decide that it does not wish to become a divorce mill for unhappy spouses who have lived there as short a time as appellant had when she commenced her action in the state court after having long resided elsewhere. Until such time as Iowa is convinced that appellant intends to remain in the State, it lacks the “nexus between person and place of such permanence as to control the creation of legal relations and responsibilities of the utmost significance.” Williams v. North Carolina, 325 U. S. 226, 229 (1945). Perhaps even more important, Iowa’s interests extend beyond its borders and include the recognition of its divorce decrees by other States under the Full Faith and Credit Clause of the Constitution, Art. IV, § 1. For that purpose, this Court has often stated that “judicial power to grant a divorce — jurisdiction, strictly speaking — is founded on domicil.” Williams, supra; Andrews v. Andrews, 188 U. S. 14 (1903); Bell v. Bell, 181 U. S. 175 (1901). Where a divorce decree is entered after a finding of domicile in ex parte proceedings, this Court has held that the finding of domicile is not binding upon another State and may be disregarded in the face of “cogent evidence” to the contrary. Williams, supra, at 236. For that reason, the State asked to enter such a decree is entitled to insist that the putative divorce petitioner satisfy something more than the bare minimum of constitutional requirements before a divorce may be granted. The State’s decision to exact a one-year residency requirement as a matter of policy is therefore buttressed by a quite permissible inference that this requirement not only effectuates state substantive policy but likewise provides a greater safeguard against successful collateral attack than would a requirement of bona fide residence alone. This is precisely the sort of determination that a State in the exercise of its domestic relations jurisdiction is entitled to make.
  We therefore hold that the state interest in requiring that those who seek a divorce from its courts be genuinely-attached to the State, as well as a desire to insulate divorce decrees from the likelihood of collateral attack, requires a different resolution of the constitutional issue presented than was the case in Shapiro, supra, Dunn, supra, and Maricopa County, supra.
  Nor are we of the view that the failure to provide an individualized determination of residency violates the Due Process Clause of the Fourteenth Amendment. Vlandis v. Kline, 412 U. S. 441 (1973), relied upon by appellant, held that Connecticut might not arbitrarily invoke a permanent and irrebuttable presumption of non-residence against students who sought to obtain in-state tuition rates when that presumption was not necessarily or universally true in fact. But in Vlandis the Court warned that its decision should not “be construed to deny a State the right to impose on a student, as one element in demonstrating bona fide residence, a reasonable durational residency requirement.” Id., at 452. See Starns v. Malkerson, 326 F. Supp. 234 (Minn. 1970), aff’d, 401 U. S. 985 (1971). An individualized determination of physical presence plus the intent to remain, which appellant apparently seeks, would not entitle her to a divorce even if she could have made such a showing. For Iowa requires not merely “domicile” in that sense, but residence in the State for a year in order for its courts to exercise their divorce jurisdiction.
  In Boddie v. Connecticut, supra, this Court held that Connecticut might not deny access to divorce courts to those persons who could not afford to pay the required fee. Because of the exclusive role played by the State in the termination of marriages, it was held that indigents could not be denied an opportunity to be heard “absent a countervailing state interest of overriding significance.” 401 U. S., at 377. But the gravamen of appellant Sosna’s claim is not total deprivation, as in Boddie, but only delay. The operation of the filing fee in Boddie served to exclude forever a certain segment of the population from obtaining a divorce in the courts of Connecticut. No similar total deprivation is present in appellant’s case, and the delay which attends the enforcement of the one-year durational residency requirement is, for the reasons previously stated, consistent with the provisions of the United States Constitution.
  Affirmed.
  Iowa Code § 598.6 (1973) provides:
  “Except where the respondent is a resident of this state and is served by personal service, the petition for dissolution of marriage, in addition to setting forth the information required by section 598.5, must state that the petitioner has been for the last year a resident of the state, specifying the county in which the petitioner has resided, and the length of such residence therein after deducting all absences from the state; and that the maintenance of the residence has been in good faith and not for the purpose of obtaining a marriage dissolution only.”
  Iowa Code § 598.9 (1973) requires dismissal of the action “[i]f the averments as to residence are not fully proved.”
  In their answer to the complaint, appellees asserted that the court lacked jurisdiction over the State by virtue of the Eleventh Amendment, but thereafter abandoned this defense to the action. While the failure of the State to raise the defense of sovereign immunity in the District Court would not have barred Iowa from raising that issue in this Court, Edelman v. Jordan, 415 U. S. 651 (1974) ; Ford Motor Co. v. Department of Treasury of Indiana, 323 U. S. 459 (1945), no such defense has been advanced in this Court. The failure of Iowa to raise the issue has likewise left us without any guidance from the parties’ briefs as to the circumstances under which Iowa law permits waiver of the defense of sovereign immunity by attorneys representing the State. Our own examination of Iowa precedents discloses, however, that the Iowa Supreme Court has held that the State consents to suit and waives any defense of sovereign immunity by entering a voluntary appearance and defending a suit on the merits. McKeown v. Brown, 167 Iowa 489, 499, 149 N. W. 593, 597 (1914). The law of Iowa on the point therefore appears to be different from the law of Indiana treated in Ford, supra.
  Our request that the parties address themselves to Younger v. Harris, 401 U. S. 37 (1971), and related cases, indicated our concern as to whether either this Court or the District Court should reach the merits of the constitutional issue presented by the parties in light of appellant Sosna’s failure to appeal the adverse ruling of the State District Court through the state appellate network. In response to our request, both parties urged that we reach the merits of appellant’s constitutional attack on Iowa’s durational residency requirement.
  In this posture of the case, and in the absence of a disagreement between the parties, we have no occasion to consider whether any consequences adverse to appellant resulted from her first obtaining an adjudication of her claim on the merits in the Iowa state court and only then commencing this action in the United States District Court.
  Since jurisdiction was predicated on 28 U. S. C. § 1343 (3), this case presents no problem of aggregation of claims in an attempt to satisfy the requisite amount in controversy of 28 U. S. C. § 1331 (a). Cf. Zahn v. International Paper Co., 414 U. S. 291 (1973); Snyder v. Harris, 394 U. S. 332 (1969). Although the'complaint did not so specify, the absence of a claim for monetary relief and the nature of the claim asserted disclose that a Rule 23 (b) (2) class action was contemplated.' Therefore, the problems associated with a Rule 23 (b) (3) class action, which were considered by this Court last Term in Eisen v. Carlisle & Jacquelin, 417 U. S. 156 (1974), are not present in this case.
  The defendant state-court- judge neither raised any claims of immunity as a defense to appellant's action, nor questioned the propriety of the appellant’s effort to represent a statewide class against a judge like him who apparently sat in a single county or judicial district within the State.
  The District Court was aware of the possibility of mootness, 360 F. Supp. 1182, 1183 n. 5 (ND Iowa 1973), and expressed the view that even the “termination of plaintiff’s deferral period . . . would not render this case moot since the cause before us is a class aetion and the court is confronted with the reasonable likelihood that the problem will occur to members of the class of which plaintiff is currently a member.”
  Counsel for appellant disclosed at oral argument that appellant has in fact obtained a divorce in New York. Tr. of Oral Arg. 22.
  The certification of a suit as a class action has important consequences for the unnamed members of the class. If the suit proceeds to judgment on the merits, it is contemplated that the decision will bind all persons who have been found at the time of certification to be members of the class. Rule 23 (c) (3); Advisory Committee Note, 28 U. S. C. App., pp. 7765-7766. Once the suit is certified as a class action, it may not be settled or dismissed without the approval of the court. Rule 23 (e).
  This view draws strength from the practical demands of time. A blanket rule under which a class action challenge to a short durational residency requirement would be dismissed upon the intervening mootness of the named representative’s dispute would permit a significant class of federal claims to remain unredressed for want of a spokesman who could retain a personal adversary position throughout the course of the litigation. Such a consideration would not itself justify any relaxation of the provision of Art. Ill which limits our jurisdiction to “cases and controversies,” but it is a factor supporting the result we reach if consistent with Art. III. For the reasons stated in the text, infra, we believe that our holding here does comport with both the language of Art. Ill and our prior decisions.
  This has been the prevailing view in the Circuits. See, e. g., Cleaver v. Wilcox, 499 F. 2d 940 (CA9 1974); Rivera v. Freeman, 469 F. 2d 1159 (CA9 1972); Conover v. Montemuro, 477 F. 2d 1073 (CA3 1972); Roberts v. Union Co., 487 F. 2d 387 (CA6 1973); Shiffman v. Askew, 359 F. Supp. 1225 (MD Fla. 1973), aff’d sub nom. Makres v. Askew, 500 F. 2d 577 (CA5 1974); Moss v. Lane Co., Inc., 471 F. 2d 853 (CA4 1973). Contra: Watkins v. Chicago Housing Authority, 406 F. 2d 1234 (CA7 1969); cf. Norman v. Connecticut State Board of Parole, 458 F. 2d 497 (CA2 1972).
  There may be cases in which the controversy involving the named plaintiffs is such that it becomes moot as to them before the district court can reasonably be expected to rule on a certification motion. In such instances, whether the certification can be said to “relate back” to the filing of the complaint may depend upon the circumstances of the particular case and especially the reality of the claim that otherwise the issue would evade review.
  When this Court has entertained doubt about the continuing nature of a case or controversy, it has remanded the case to the lower court for consideration of the possibility of mootness. Indiana Employment Div. v. Burney, 409 U. S. 540 (1973).
  There are frequently cases in which it appears that the particular class a party seeks to represent does not have a sufficient homogeneity of interests to warrant certification. Hansberry v. Lee, 311 U. S. 32, 44 (1940); Phillips v. Klassen, 163 U. S. App. D. C. 360, 502 F. 2d 362 (1974), cert. denied, post, p. 996. In this case, however, it is difficult to imagine why any person in the class appellant represents would have an interest in seeing Iowa Code § 598.6 (1973) upheld.
  See generally Peters, Iowa Reform of Marriage Termination, 20 Drake L. Rev. 211 (1971).
  Louisiana and Washington are the exceptions. La. Code Civ. Proc., Art. 10A (7) (Supp. 1974); but see Art. 10B providing that “if a spouse has established and maintained a residence in a parish of this state for a period of twelve months, there shall be a rebuttable presumption that he has a domicile in this state in the parish of such residence.” Wash. Laws 1973,1st Ex. Sess., c. 157. Among the other 48 States, the durational residency requirements are of many varieties, with some applicable to all divorce actions, others only when the respondent is not domiciled in the State, and still others applicable depending on where the grounds for divorce accrued. See the 50-state compilation issued by the National Legal Aid and Defender Association, Divorce, Annulment and'Separation in the United States (1973).
  See, e. g., Idaho Code § 32-701 (1963); Nev. Rev. Stat. § 125.-020 (1973).
  See, e. g., R. I. Gen. Laws Ann. § 15-5-12 (1970); Mass. Gen. Laws Ann., e. 208, §§ 4r-5 (1958 and Supp. 1974).
  A majority of the States impose a one-year residency requirement of some kind. Divorce, Annulment and Separation in the United States, supra, n. 15.
  Shapiro, 394 U. S., at 638 n. 21; Maricopa County, 415 U. S., at 258-259.
  When a divorce decree is not entered on the basis of ex parte proceedings, this Court held in Sherrer v. Sherrer, 334 U. S. 343, 351-352 (1948):
  “[T]he requirements of full faith and credit bar a defendant from collaterally attacking a divorce decree on jurisdictional grounds in the courts of a sister State where there has been participation by the defendant in the divorce proceedings, where the defendant has been accorded full opportunity to contest the jurisdictional issues, and where the decree is not susceptible to such collateral attack in the courts of the State which rendered the decree.”
  Our Brother Marshall argues in dissent that the Iowa dura-tional residency requirement “sweeps too broadly” since it is not limited to ex parte proceedings and could be narrowed by a waiver provision. Post, at 425. But Iowa’s durational residency requirement cannot be tailored in this manner without disrupting settled principles of Iowa practice and pleading. Iowa’s rules governing special appearances make it impossible for the state court to know, either at the time a petition for divorce is filed or when a motion to dismiss for want of jurisdiction is filed, whether or not a respondent will appear and participate in the divorce proceedings. Iowa Rules Civ. Proc. 66, 104. The fact that the state legislature might conceivably adopt a system of waivers and revise court rules governing special appearances does not make such detailed rewriting appropriate business for the federal judiciary.
  Since the majority of States require residence for at least a year, see n. 18, supra, it is reasonable to assume that Iowa’s one-year "floor” makes its decrees less susceptible to successful collateral attack in other States. As the Court of Appeals for the Fifth Circuit observed in upholding a six-month durational residency requirement imposed by Florida, an objective test may impart to a State’s divorce decrees “a verity that tends to safeguard them against the suspicious eyes of other states’ prosecutorial authorities, the suspicions of private counsel in other states, and the post-decree dissatisfactions of parties to the divorce who wish a second bite. Such a reputation for validity of divorce decrees is not, then, merely cosmetic.” Makres v. Askew, 500 F. 2d 577, 579 (1974), aff’g 359 F. Supp. 1225 (MD Fla. 1973).
  In addition to a showing of residence within the State for a year, Iowa Code § 598.6 (1973) requires any petition for dissolution to state “that the maintenance of the residence has been in good faith and not for the purpose of obtaining a marriage dissolution only.” In dismissing appellant’s petition in state court, Judge Keck observed that appellant had failed to allege good-faith residence. (Jurisdictional Statement App. B. 2.)