opinion: ROSTKER, DIRECTOR OF SELECTIVE SERVICE v. GOLDBERG et al.
  No. 80-251.
  Argued March 24, 1981
  Decided June 25, 1981
  Rehnquist, J., delivered the opinion of the Court, in which Burger, C. J., and Stewart, Blackmun, Powell, and Stevens, JJ., joined. White, J., post, p. 83, and Marshall, J., post, p. 86, filed dissenting opinions, in which Brennan, J., joined.
  Solicitor General McCree argued the cause for appellant. With him on the briefs were Assistant Attorney General Daniel, Acting Assistant Attorney General Martin, Deputy Solicitor General Claiborne, Barbara E. Etkind, William Ranter, and Mark H. Gallant.
  Donald L. Weinberg argued the cause for appellees. With him on the brief were Harold E. Kohn, Stuart H. Savett, Isabelle Katz Pinzler, Bruce J. Ennis, and Laurence H. Tribe
  Briefs of amici curiae urging reversal were filed by Dennis Rapps and A. David Stern for the Orthodox Jewish Coalition on the Draft; and by Nathan Lewin for Stacy Acker et al.
  Briefs of amici curiae urging affirmance were filed by Daniel Marcus for Congressman Robert W. Kastenmeier et al.; by Paul Kenney for Men’s Rights, Inc.; by Barbara A. Brown, Thomas J. Hart, Phyllis N. Segal, and Judith I. .Avner for the National Organization for Women; and by Judith L. Lichtman for the Women’s Equity Action League Educational and Legal Defense Fund et al.
  Daniel J. Popeo and Paul D. Kamenar filed a brief for Congressman Lawrence P. McDonald et al. as amici curiae.
  Justice Rehnquist
  delivered the opinion of the Court.
  The question presented is whether the Military Selective Service Act, 50 U. S. C. App. § 451 et seq. (1976 ed. and Supp. III), violates the Fifth Amendment to the United States Constitution in authorizing the President to require the registration of males and not females.
  I
  Congress is given the power under the Constitution “To raise and support Armies,” “To provide and maintain a Navy,” and “To make Rules for the Government and Regulation of the land and naval Forces.” Art. I, § 8, cls. 12-14. Pursuant to this grant of authority Congress has enacted the Military Selective Service Act, 50 U. S. C. App. § 451 et seq. (1976 ed. and Supp. III) (the MSSA or the Act). Section 3 of the Act, 62 Stat. 605, as amended, 50 U. S. C. App. § 453, empowers the President, by proclamation, to require the registration of “every male citizen” and male resident aliens between the ages of 18 and 26. The purpose of this registration is to facilitate any eventual conscription: pursuant to § 4 (a) of the Act, 62 Stat. 605, as amended, 50 U. S. C. App. § 454 (a), those persons required to register under § 3 are liable for training and service in the Armed Forces. The MSSA registration provision serves no other purpose beyond providing a pool for subsequent induction.
  Registration for the draft under § 3 was discontinued in 1975. Presidential Proclamation No. 4360, 3 CFR 462 (1971-1975 Comp.), note following 50 U. S. C. App. §453. In early 1980, President Carter determined that it was necessary to reactivate the draft registration process. The immediate impetus for this decision was the Soviet armed invasion of Afghanistan. 16 Weekly Comp, of Pres. Doc. 198 (1980) (State of the Union Address). According to the administration’s witnesses before the Senate Armed Services Committee, the resulting crisis in Southwestern Asia convinced the President that the “time has come” “to use his present authority to require registration ... as a necessary step to preserving or enhancing our national security interests.” Department of Defense Authorization for Appropriations for Fiscal Year 1981: Hearings on S. 2294 before the Senate Committee on Armed Services, 96th Cong., 2d Sess., 1805 (1980) (hereafter Hearings on S. 2294) (joint statement of Dr. John P. White, Deputy Director, Office of Management and Budget, Dr. Bernard Rostker, Director, Selective Service System, and Richard Danzig, Principal Deputy Assistant Secretary of Defense). The Selective Service System had been inactive, however, and funds were needed before reactivating registration. The President therefore recommended that funds be transferred from the Department of Defense to the separate Selective Service System. H. R. Doc. No. 96-267, p. 2 (1980). He also recommended that Congress take action to amend the MSSA to permit the registration and conscription of women as well as men. See House Committee on Armed Services, Presidential Recommendations for Selective Service Reform — A Report to Congress Prepared Pursuant to Pub. L. 96-107, 96th Cong., 2d Sess., 20-23 (Comm. Print No. 19, 1980) (hereinafter Presidential Recommendations), App. 57-61.
  Congress agreed that it was necessary to reactivate the registration process, and allocated funds for that purpose in a Joint Resolution which passed the House on April 22 and the Senate on June 12. H. J. Res. 521, Pub. L. 96-282, 94 Stat. 552. The Resolution did not allocate all the funds originally requested by the President, but only those necessary to register males. See S. Rep. No. 96-789, p. 1, n. 1, and p. 2 (1980); 126 Cong. Rec. 13895 (1980) (Sen. Nunn). Although Congress considered the question at great length, see infra, at 72-74, it declined to amend the MSSA to permit the registration of women.
  On July 2, 1980, the President, by Proclamation, ordered the registration of specified groups of young men pursuant to the authority conferred by § 3 of the Act. Registration was to commence on July 21, 1980. Proclamation No. 4771, 3 CFR 82 (1980).
  These events of last year breathed new life into a lawsuit which had been essentially dormant in the lower courts for nearly a decade. It began in 1971 when several men subject to registration for the draft and subsequent induction into the Armed Services filed a complaint in the United States District Court for the Eastern District of Pennsylvania challenging the MSSA on several grounds. A three-judge Dis-strict Court was convened in 1974 to consider the claim of unlawful gender-based discrimination which is now before us. On July 1, 1974, the court declined to dismiss the case as moot, reasoning that although authority to induct registrants had lapsed, see n. 1, supra, plaintiffs were still under certain affirmative obligations in connection with registration. Rowland v. Tarr, 378 F. Supp. 766. Nothing more happened in the case for five years. Then, on June 6, 1979, the court Clerk, acting pursuant to a local rule governing inactive cases, proposed that the case be dismissed. Additional discovery thereupon ensued, and defendants moved to dismiss on various justiciability grounds. The court denied the motion to dismiss, ruling that it did not have before it an adequate record on the operation of the Selective Service System and what action would be necessary to reactivate it. Goldberg v. Tarr, 510 F. Supp. 292 (1980). On July 1, 1980, the court certified a plaintiff class of “all male persons who are registered or subject to registration under 50 U. S. C. App. § 453 or are liable for training and service in the armed forces of the United States under 50 U. S. C. App. §§ 454, 456 (h) and 467 (c).” 509 F. Supp. 586, 589,
  On Friday, July 18, 1980, three days before registration was to commence, the District Court issued an opinion finding that the Act violated the Due Process Clause of the Fifth Amendment and permanently enjoined the Government from requiring registration under the Act. The court initially determined that the plaintiffs had standing and that the case was ripe, determinations which are not challenged here by the Government. Turning to the merits, the court rejected plaintiffs’ suggestions that the equal protection claim should , be tested under “strict scrutiny,” and also rejected defendants’ argument that the deference due Congress in the area of military affairs required application of the traditional 'minimum scrutiny” test. Applying the “important government interest” test articulated in Craig v. Boren, 429 U. S. 190 (1976), the court struck down the MSSA. The court stressed that it was not deciding whether or to what extent women should serve in combat, but only the issue of registration, and felt that this “should dispel any concern that we are injecting ourselves in an inappropriate manner into military affairs.” 509 F. Supp., at 597. See also id., at 599, nn. 17 and 18. The court then proceeded to examine the testimony and hearing evidence presented to Congress by representatives of the military and the Executive Branch, and concluded on the basis of this testimony that “military opinion, backed by extensive study, is that the availability of women registrants would materially increase flexibility, not hamper it.” Id., at 603. It rejected Congress’ contrary determination in part because of what it viewed as Congress’ “inconsistent positions” in declining to register women yet spending funds to recruit them and expand their opportunities in the military. Ibid.
  The Director of Selective Service immediately filed a notice of appeal and the next day, Saturday, July 19, 1980, Justice Brennan, acting in his capacity as Circuit Justice for the Third Circuit, stayed the District Court’s order enjoining commencement of registration. 448 U. S. 1306. Registration began the next Monday. On December 1, 1980, we noted probable jurisdiction. 449 U. S. 1009.
  II
  Whenever called upon to judge the constitutionality of an Act of Congress -“the gravest and) most delicate duty that this Court is called upon to perform,” Blodgett v. Holden, 275 U. S. 142, 148 (1927) (Holmes, J.) — the Court accords “great weight to the decisions of Congress.” Columbia Broadcasting System, Inc. v. Democratic National Committee, 412 U. S. 94, 102 (1973). The Congress is a coequal branch of government whose Members take the same oath we do to uphold the Constitution of the United States. As Justice Frankfurter noted in Joint Anti-Fascist Refugee Committee v. McGrath, 341 U. S. 123, 164 (1951) (concurring opinion), we must have “due regard to the fact that this Court is not exercising a primary judgment but is sitting in judgment upon those who also have taken the oath to observe the Constitution and who have the responsibility for carrying on government.” The customary deference accorded the judgments of Congress is certainly appropriate when, as here, Congress specifically considered the question of the Act’s constitutionality. See, e. g., S. Rep. No. 96-826, pp. 159-161 (1980); 126 Cong. Rec. 13880-13882 (1980) (Sen. Warner); id., at 13896 (Sen. Hatfield).
  This is not, however, merely a case'involving the customary deference accorded congressional decisions. The case ^arises in the context of Congress’ authority over national defense and military affairs, and perhaps in no other area has the Court accorded Congress greater deference. In rejecting the registration of women, Congress explicitly relied upon its constitutional powers under Art. I, § 8, cls. 12-14. The “specific findings” section of the Report of the Senate Armed Services Committee, later adopted by both Houses of Congress, began by stating:
  “Article I, séction 8 of the Constitution commits exclusively to the Congress the powers to raise and support armies, provide and maintain a Navy, and make rules for Government and regulation of the land and naval forces, and pursuant to these powers it lies within the discretion of the Congress to determine the occasions for expansion of our Armed Forces, and the means best suited to such expansion should it prove necessary.” S. Rep. No. 96-826, supra, at 160.
  See also S. Rep. No. 96-226, p. 8 (1979). This Court has consistently recognized Congress’ “broad constitutional power” to raise and regulate armies and navies, Schlesinger v. Ballard, 419 U. S. 498, 510 (1975). As the Court noted in considering a challenge to the selective service laws: “The constitutional power of Congress to raise and support armies and to make all laws necessary and proper to that end is broad and sweeping.” United States v. O’Brien, 391 U. S. 367, 377 (1968). See Lichter v. United States, 334 U. S. 742, 755 (1948).
  Not only is the scope of Congress’ constitutional power in this area broad, but the lack of competence on the part of the courts is marked. In Gilligan v. Morgan, 413 U. S. 1, 10 (1973), the Court noted:
  “[I]t is difficult to conceive of an area of governmental activity in which the courts have less competence. The complex, subtle, and professional decisions as to the composition, training, equipping, and control of a military force are essentially professional military judgments, subject always to civilian control of the Legislative and Executive Branches.”
  See also Orloff v. Willoughby, 345 U. S. 83, 93-94 (1953).
  The operation of a healthy deference to legislative and executive judgments in the area of military affairs is evident in several recent decisions of this Court. In Parker v. Levy, 417 U. S. 733, 756, 758 (1974), the Court rejected both vagueness and overbreadth challenges to provisions of the Uniform Code of Military Justice, noting that “Congress is permitted to legislate both with greater breadth and with greater flexibility” when the statute governs military society, and that “[w]hile the members of the military are not excluded from the protection granted by the First Amendment, the different character of the military community and of the military mission requires a different application of those protections.” In Middendorf v. Henry, 425 U. S. 25 (1976), the Court noted that in considering due process claims in the context of a summary court-martial it “must give particular deference to the determination of Congress, made under its authority to regulate the land and naval forces, U. S. Const., Art. I, § 8,” concerning what rights were available. Id., at 43. See also id., at 49-50 (Powell, J., concurring). Deference to the judgment of other branches in the area of military affairs also played a major role in Greer v. Spock, 424 U. S. 828, 837-838 (1976), where the Court upheld a ban on political speeches by civilians on a military base, and Brown v. Glines, 444 U. S. 348 (1980), where the Court upheld regulations imposing a prior restraint on the right to petition of military personnel. See also Burns v. Wilson, 346 U. S. 137 (1953); United States v. MacIntosh, 283 U. S. 605, 622 (1931).
  In Schlesinger v. Ballard, supra, the Court considered a due process challenge, brought by males, to the Navy policy of according females a longer period than males in which to attain promotions necessary to continued service. The Court distinguished previous gender-based discriminations held unlawful in Reed v. Reed, 404 U. S. 71 (1971), and Frontiero v. Richardson, 411 U. S. 677 (1973). In those cases, the classifications were based on “overbroad generalizations.” See 419 U. S., at 506-507. In the case before it, however, the Court noted:
  “[T]he different treatment of men and women naval officers . . . reflects, not archaic and overbroad generalizations, but, instead, the demonstrable fact that male and female line officers in the Navy are not similarly situated with respect to opportunities for professional service. Appellee has not challenged the current restrictions on women officers’ participation in combat and in most sea duty.” Id., at 508.
  In light of the combat restrictions, women did not have the same opportunities for promotion as men, and therefore it was not unconstitutional for Congress to distinguish between them.
  None of this is to say that Congress is free to disregard the Constitution when it acts in the area of military affairs. In that area, as any other, Congress remains subject to the limitations of the Due Process Clause, see Ex parte Milligan, 4 Wall. 2 (1866); Hamilton v. Kentucky Distilleries & Warehouse Co., 251 U. S. 146, 156 (1919), but the tests and limitations to be applied may differ because of the military context. We of course do not abdicate our ultimate responsibility to decide the constitutional question, but simply recognize that the Constitution itself requires such deference to congressional choice. See Columbia Broadcasting System, Inc. v. Democratic National Committee, 412 U. S., at 103. In deciding the question before us we must be particularly careful not to substitute our judgment of what is desirable for that of Congress, or our own evaluation of evidence for a reasonable evaluation by the Legislative Branch.
  The District Court purported to recognize the appropriateness of deference to Congress when that body was exercising its constitutionally delegated authority over military affairs, 509 F. Supp., at 596, but it stressed that “[w]e are not here concerned with military operations or day-to-day conduct of the military into which we have no desire to intrude.” Ibid. Appellees also stress that this case involves civilians, not the military, and that “the impact of registration on the military is only indirect and attenuated.” Brief for Appellees 19 (emphasis omitted). We find these efforts to divorce registration from the military and national defense context, with all the deference called for in that context, singularly unpersuasive. United States v. O’Brien, 391 U. S. 367 (1968), recognized the broad deference due Congress in the selective service area before us in this case. Registration is not an end in itself in the civilian world but rather the first step in the induction process into the military one, and Congress specifically linked its consideration of registration to induction, see, e. g., S. Rep. No. 96-826, pp. 156, 160 (1980). Congressional judgments concerning registration and the draft are based on judgments concerning military operations and needs, see, e. g., id., at 157 (“the starting point for any discussion of the appropriateness of registering women for the draft is the question of the proper role of women in combat”), and the deference unquestionably due the latter judgments is necessarily required in assessing the former as well. Although the District Court stressed that it was not intruding on military questions, its opinion was based on assessments of military need and flexibility in a time of mobilization. See, e. g., 509 F. Supp., at 600-605. It would be blinking reality to say that our precedents requiring deference to Congress in military affairs are not implicated by the present case.
  The Solicitor General argues, largely on the basis of the foregoing cases emphasizing the deference due Congress in the area of military affairs and national security, that this Court should scrutinize the MSSA only to determine if the distinction drawn between men and women bears a rational relation to some legitimate Government purpose, see U. S. Railroad Retirement Bd. v. Fritz, 449 U. S. 166 (1980), and should not examine the Act under the heightened scrutiny with which we have approached gender-based discrimination, see Michael M. v. Superior Court of Sonoma County, 450 U. S. 464 (1981); Craig v. Boren, 429 U. S. 190 (1976); Reed v. Reed, supra. We do not think that the substantive guarantee of due process or certainty in the law will be advanced by any further “refinement” in the applicable tests as suggested by the Government. Announced degrees of “deference” to legislative judgments, just as levels of “scrutiny” which this Court announces that it applies to particular classifications made by a legislative body, may all too readily become facile abstractions used to justify a result. In this case the courts are called upon to decide whether Congress, acting under an explicit constitutional grant of authority, has by that action transgressed an explicit guarantee of individual rights which limits the authority so conferred. Simply labeling the legislative decision “military” on the one hand or “gender-based” on the other does not automatically guide a court to the correct constitutional result.
  No one could deny that under the test of Craig v. Boren, supra, the Government’s interest in raising and supporting armies is an “important governmental interest.” Congress and its Committees carefully considered and debated two alternative means of furthering that interest: the first was to register only males for potential conscription, and the other was to register both sexes. Congress chose the former alternative. When that decision is challenged on equal protection grounds, the question a court must decide is not which alternative it would have chosen, had it been the primary decision-maker, but whether that chosen by Congress denies equal protection of the laws.
  Nor can it be denied that the imposing number of cases from this Court previously cited suggest that judicial deference to such congressional exercise of authority is at its apogee when legislative action under the congressional authority to raise and support armies and make rules and regulations for their governance is challenged. As previously noted, supra, at 67, deference does not mean abdication. The reconciliation between the deference due Congress and our own constitutional responsibility is perhaps best instanced in Schlesinger v. Ballard, 419 U. S., at 510, where we stated:
  “This Court has recognized that fit is the primary business of armies and navies to fight or be ready to fight wars should the occasion arise.’ [U. S. ex rel.] Toth v. Quarles, 350 U. S. 11, 17. See also Orloff v. Willoughby, 345 U. S. 83, 94. The responsibility for determining how best our Armed Forces shall attend to that business rests with Congress, see U. S. Const., Art. I, § 8, cls. 12-14, and with the President. See U. S. Const., Art. II, § 2, cl. 1. We cannot say that, in exercising its broad constitutional power here, Congress has violated the Due Process Clause of the Fifth Amendment.”
  Or, as put a generation ago in a case not involving any claim of gender-based discrimination:
  “[JJudges are not given the task of running the Army. The responsibility for setting up channels through which . . . grievances can be considered and fairly settled rests upon the Congress and upon the President of the United States and his subordinates. The military constitutes a specialized community governed by a separate discipline from that of the civilian. Orderly government requires that the judiciary be as scrupulous not to interfere with legitimate Army matters as the Army must be scrupulous not to intervene in judicial matters.” Orloff v. Willoughby, 345 U. S., at 93-94.
  Schlesinger v. Ballard did not purport to apply a different equal protection test because of the military context, but did stress the deference due congressional choices among alternatives in exercising the congressional authority to raise and support armies and make rules for their governance. In light of the floor debate and the Report of the Senate Armed Services Committee hereinafter discussed, it is apparent that Congress was fully aware not merely of the many facts and figures presented to it by witnesses who testified before its Committees, but of the current thinking as to the place of women in the Armed Services. In such a case, we cannot ignore Congress’ broad authority conferred by the Constitution to raise and support armies when we are urged to declare unconstitutional its studied choice of one alternative in preference to another for furthering that goal.
  Ill
  This case is quite different from several of the gender-based ^discrimination cases we have considered in that, despite appel-lees' assertions, Congress did not act “unthinkingly” or “reflexively and not for any considered reason.” Brief for Appellees 35. The question of registering women for the draft not only received considerable national attention and was the subject of wide-ranging public debate, but also was extensively considered by Congress in hearings, floor debate, and in committee. Hearings held by both Houses of Congress in response to the President's request for authorization to register women adduced extensive testimony and evidence concerning the issue. See Hearings on S. 2294; Hearings on H. R. 6569, Registration of Women, before the Subcommittee on Military Personnel of the House Committee on Armed Services, 96th Cong., 2d Sess. (1980) (hereafter House Hearings). These hearings built on other hearings held the previous year addressed to the same question.
  The House declined to provide for the registration of women when it passed the Joint Resolution allocating funds for the Selective Service System. See 126 Cong. Rec. 8601-8602, 8620 (1980). When the Senate considered the Joint Resolution, it defeated, after extensive debate, an amendment which in effect would have authorized the registration of women. Id., at 13876-13898. As noted earlier, Congress in H. J. Res. 521 only authorized funds sufficient to cover the registration of males. The Report of the Senate Committee on Appropriations on H. J. Res. 521 noted that the amount authorized was below the President’s request “due to the Committee’s decision not to provide $8,500,000 to register women,” and that “[t]he amount recommended by the Committee would allow for registration of young men only.” S. Rep. No. 96-789, p. 2 (1980); see 126 Cong. Rec. 13895 (1980) (Sen. Nunn).
  While proposals to register women were being rejected in the course of transferring funds to register males, Committees in both Houses which had conducted hearings on the issue were also rejecting the registration of women. The House Subcommittee on Military Personnel of the House Armed Services Committee tabled a bill which would have amended the MSSA to authorize registration of women, H. R. 6569, on March 6, 1980. Legislative Calendar, House Committee on Armed Services, 96th Cong., 2d Sess., 58 (1979-1980). The Senate Armed Services Committee rejected a proposal to register women, S. 2440, as it had one year before, see S. Rep. No. 96-226, pp. 8-9 (1979), and adopted specific findings supporting its action. See S. Rep. No. 96-826, pp. 156-161 (1980). These findings were stressed in debate in the Senate on Joint Resolution 521, see 126 Cong. Rec. 13893-13894 (1980) (Sen. Nunn); id., at 13880-13881 (Sen. Warner). They were later specifically endorsed by House and Senate conferees considering the Fiscal Year 1981 Defense Authorization Bill. See S. Conf. Rep. No. 96-895, p. 100 (1980). Later both Houses adopted the findings by passing the Report. 126 Cong. Rec. 23126, 23261 (1980). The Senate Report, therefore, is considerably more significant than a typical report of a single House, and its findings are in effect findings of the entire Congress.
  The foregoing clearly establishes that the decision to ex-women from registration was not the “ 'accidental byproduct of a traditional way of thinking about females/” Califano v. Webster, 430 U. S. 313, 320 (1977) (quoting Califano v. Goldfarb, 430 U. S. 199, 223 (1977) (Stevens, J., concurring in judgment)). In Michael M., 450 U. S., at 471, n. 6 (plurality opinion), we rejected a similar argument because of action by the California Legislature considering and rejecting proposals to make a statute challenged on discrimination grounds gender-neutral. The cause for rejecting the argument is considerably stronger here. The issue was considered at great length, and Congress clearly expressed its purpose and intent. Contrast Califano v. Westcott, 443 U. S. 76, 87 (1979) (“The gender qualification . . . escaped virtually unnoticed in the hearings and floor debates”).
  For the same reasons we reject appellees’ argument that we must consider the constitutionality of the MSSA solely on the basis of the views expressed by Congress in 1948, when the MSSA was first enacted in its modern form. Contrary to the suggestions of appellees and various amici, reliance on the legislative history of Joint Resolution 521 and the activity of the various Committees of the 96th Congress considering the registration of women does not violate sound principles that appropriations legislation should not be considered as modifying substantive legislation. Congress did not change the MSSA in 1980, but it did thoroughly reconsider the question of exempting women from its provisions, and its basis for doing so. The 1980 legislative history is, therefore, highly relevant in assessing the constitutional validity of the exemption.
  The MSSA established a plan for maintaining “adequate armed strength ... to insure the security of [the] Nation.” 50 U. S. C. App. §451 (b). Registration is the first step “in a united and continuous process designed to raise an army speedily and efficiently,” Falbo v. United States, 320 U. S. 549, 553 (1944), see United States v. Nugent, 346 U. S. 1, 9 (1953), and Congress provided for the reactivation of registration in order to “provid [e] the means for the early delivery of inductees in an emergency.” S. Rep. No. 96-826, supra, at 156. Although the three-judge District Court often tried to sever its consideration of registration from the particulars of induction, see, e. g., 509 F. Supp., at 604-605, Congress rather clearly linked the need for renewed registration with its views on the character of a subsequent draft. The Senate Report specifically found that “[a]n ability to mobilize rapidly is essential to the preservation of our national security. ... A functioning registration system is a vital part of any mobilization plan.” S. Rep. No. 96-826, supra, at 160. As Senator Warner put it, “I equate registration with the draft.” Hearings on S. 2294, at 1197. See also id., at 1195 (Sen. Jepsen), 1671 (Sen. Exon). Such an approach is certainly logical, since under the MSSA induction interlocked with registration: only those registered may be drafted, and registration serves no purpose beyond providing pool for the draft. Any assessment of the congressional purpose and its chosen means must therefore consider the registration scheme as a prelude to a draft in a time of national emergency. Any other approach would not be testing the Act in light of the purposes Congress sought to achieve.
  Congress determined that any future draft, which would be facilitated by the registration scheme, would be characterized by a need for combat troops. The Senate Report explained, in a specific finding later adopted by both Houses, that “[i]f mobilization were to be ordered in a wartime scenario, the primary manpower need would be for combat replacements.” S. Rep. No. 96-826, p. 160 (1980); see id., at 158. This conclusion echoed one made a year before by the same Senate Committee, see S. Rep. No. 96-226, pp. 2-3, 6 (1979). As Senator Jepsen put it, “the shortage would be in the combat arms. That is why you have drafts.” Hearings on S. 2294, at 1688. See also id., at 1195 (Sen. Jepsen); 126 Cong. Rec. 8623 (1980) (Rep. Nelson). Congress’ determination that the need would be for combat troops if a draft took place was sufficiently supported by testimony adduced at the hearings so that the courts are not free to make their own judgment on the question. See Hearings on S. 2294, at 1528-1529 (Marine Corps Lt. Gen. Bronars); 1395 (Principal Deputy Assistant Secretary of Army Clark); 1391 (Lt. Gen. Yerks); 748 (Gen. Meyer); House Hearings 17 (Assistant Secretary of Defense for Manpower Pirie). See also Hearing on S. 109 and S. 226, at 24, 54 (Gen. Rogers). The purpose of registration, therefore, was to prepare for a draft of combat troops.
  Women as a group, however, unlike men as a group, are not eligible for combat. The restrictions on the participation of women in combat in the Navy and Air Force are statutory. Under 10 U. S. C. § 6015 (1976 ed., Supp. III), “women may not be assigned to duty on vessels or in aircraft that are engaged in combat missions,” and under 10 U. S. C. § 8549 female members of the Air Force “may not be assigned to duty in aircraft engaged in combat missions.” The Army and Marine Corps preclude the use of women in combat as a matter of established policy. See App. 86, 34, 58. Congress specifically recognized and endorsed the exclusion of women from combat in exempting women from registration. In the words of the Senate Report:
  “The principle that women should not intentionally and routinely engage in combat is fundamental, and enjoys wide support among our people. It is universally supported by military leaders who have testified before the Committee .... Current law and policy exclude women from being assigned to combat in our military forces, and the Committee reaffirms this policy.” S. Rep. No. 96-826, supra, at 157.
  The Senate Report specifically found that “[wjomen should not be intentionally or routinely placed in combat positions in our military services.” Id., at 160. See S. Rep. No. 96-226, supra, at 9. The President expressed his intent to continue the current military policy precluding women from combat, see Presidential Recommendations 3, App. 34, and appellees present their argument concerning registration against the background of such restrictions on the use of women in combat. Consistent with the approach of this Court in Schlesinger v. Ballard, 419 U. S. 498 (1975), we must examine appellees’ constitutional claim concerning registration with these combat restrictions firmly in mind.
  . The existence of the combat restrictions clearly indicates the basis for Congress’ decision to exempt women from registration. The purpose of registration was to prepare for a draft of combat troops. Since women are excluded from combat, Congress concluded that they would not be needed in the event of a draft, and therefore decided not to register them. Again turning to the Senate Report:
  “In the Committee’s view, the starting point for any discussion of the appropriateness of registering women for the draft is the question of the proper role of women in combat. . . . The policy precluding the use of women in combat is, in the Committee’s view, the most important reason for not including women in a registration system.” S. Rep. No. 96-826, supra, at 157.
  The District Court stressed that the military need for women was irrelevant to the issue of their registration. As that court put it: “Congress could not constitutionally require registration under the MSSA of only black citizens or only white citizens, or single out any political or religious group simply because those groups contain sufficient persons to fill the needs of the Selective Service System.” 509 P. Supp., at 596. This reasoning is beside the point. The reason women are exempt from registration is not because military needs can be met by drafting men. This is not a case oh Congress arbitrarily choosing to burden one of two similarly situated groups, such as would be the case with an all-black or all-white, or an all-Catholic or all-Lutheran, or an all-Republican or all-Democratic registration. Men and women, because of the combat restrictions on women, are simply not similarly situated for purposes of a draft or registration for a draft.
  Congress’ decision to authorize the registration of only men, therefore, does not violate the Due Process Clause. The exemption of women from registration is not only sufficiently but also closely related to Congress’ purpose in authorizing registration. See Michael M., 450 U. S., at 472-473 (plurality opinion); Craig v. Boren, 429 U. S. 190 (1976); Reed v. Reed, 404 U. S. 71 (1971). The fact that Congress and the Executive have decided that women should not serve in combat fully justifies Congress in not authorizing their registration, since the purpose of registration is to develop a pool of potential combat troops. As was the case in Schlesinger v. Ballard, supra, “the gender classification is not individious, but rather realistically reflects the fact that the sexes are not similarly situated” in this case. Michael M., supra, at 469 (plurality opinion). The Constitution requires that Congress treat similarly situated persons similarly, not that it engage in gestures of superficial equality.
  In holding the MSSA constitutionally invalid the District Court relied heavily on the President’s decision to seek authority to register women and the testimony of members of the Executive Branch and the military in support of that decision. See, e. g., 509 F. Supp., at 603-604, and n. 30. As stated by the administration’s witnesses before Congress, however, the President’s “decision to ask for authority to register women is based on equity.” House Hearings 7 (statement of Assistant Secretary of Defense Pirie and Director of Selective Service System Rostker); see also Presidential Recommendations 3, 21, 22, App. 35, 59, 60; Hearings on S. 2294, at 1657 (statements of Executive Associate Director of Office of Management and Budget Wellford, Director of Selective Service System Rostker, and Principal Deputy Assistant Secretary of Defense Danzig). This was also the basis for the testimony by military officials. Id., at 710 (Gen. Meyer), 1002 (Gen. Allen). The Senate Report, evaluating the testimony before the Committee, recognized that “[t]he argument for registration and induction of women ... is not based on military necessity, but on considerations of equity.” S. Rep. No. 96-826, p. 158 (1980). Congress was certainly entitled, in the exercise of its constitutional powers to raise and regulate armies and navies, to focus on the question of military need rather than “equity.” As Senator Nunn of the Senate Armed Services Committee put it:
  “Our committee went into very great detail. We found that there was no military necessity cited by any witnesses for the registration of females.
  “The main point that those who favored the registra-tration of females made was that they were in favor of this because of the equality issue, which is, of course, a legitimate view. But as far as military necessity, and that is what we are primarily, I hópe, considering in the overall registration bill, there is no military necessity for this.” 126 Cong. Rec. 13893 (1980).
  See also House Hearings 20 (Rep. Holt) (“You are talking about equity. I am talking about military”).
  Although the military experts who testified in favor of registering women uniformly opposed the actual drafting of women, see, e. g., Hearing on S. 109 and S. 226, at 11 (Gen. Rogers), there was testimony that in the event of a draft of 650,000 the military could absorb some 80,000 female inductees. Hearings on S. 2294, at 1661, 1828. The 80,000 would be used to fill noncombat positions, freeing men to go to the front. In relying on this testimony in striking down the MSSA, the District Court palpably exceeded its authority when it ignored Congress’ considered response to this fine of reasoning.
  In the first place, assuming that a small number of women could be drafted for noncombat roles, Congress simply did not consider it worth the added burdens of including women in draft and registration plans. “It has been suggested that all women be registered, but only a handful actually be inducted in an emergency. The Committee finds this a confused and ultimately unsatisfactory solution.” S. Rep. No. 96-826, supra, at 158. As the Senate Committee recognized a year before, “training would be needlessly burdened by women recruits who could not be used in combat.” S. Rep. No. 96-226, p. 9 (1979). See also S. Rep. No. 96-826, supra, at 159 (“Other administrative problems such as housing and different treatment with regard to dependency, hardship and physical standards would also exist”). It is not for this Court to dismiss such problems as insignificant in the context of military preparedness and the exigencies of a future mobilization.
  Congress also concluded that whatever the need for women for noncombat roles during mobilization, whether 80,000 or less, it could be met by volunteers. See id., at 160; id., at 158 (“Because of the combat restrictions, the need would be primarily for men, and women volunteers would fill the requirements for women”); House Hearings 19 (Rep. Holt). See also Hearings on S. 2294, at 1195 (Gen. Rogers).
  Most significantly, Congress determined that staffing noncombat positions with women during a mobilization would be positively detrimental to the important goal of military flexibility.
  . . [T]here are other military reasons that preclude very large numbers of women from serving. Military flexibility requires that a commander be able to move units or ships quickly. Units or ships not located at the front or not previously scheduled for the front nevertheless must be able to move into action if necessary. In peace and war, significant rotation of personnel is necessary. We should not divide the military into two groups — one in permanent combat and one in permanent support. Large numbers of non-combat positions must be available to which combat troops can return for duty before being redeployed.” S. Rep. No. 96-826, supra, at 158.
  The point was repeated in specific findings, id., at 160; see also S. Rep. No. 96-226, supra, at 9. In sum, Congress carefully evaluated the testimony that 80,000 women conscripts could be usefully employed in the event of a draft and rejected it in the permissible exercise of its constitutional responsibility. See also Hearing on S. 109 and S. 226, at 16 (Gen. Rogers); Hearings on S. 2294, at 1682. The District Court was quite wrong in undertaking an independent evaluation of this evidence, rather than adopting an appropriately deferential examination of Congress’ evaluation of that evidence.
  In light of the foregoing, we conclude that Congress acted well within its constitutional authority when it authorized the registration of men, and not women, under the Military Selective Service Act. The decision of the District Court holding otherwise is accordingly
  Reversed.
  The President did not seek conscription. Since the Act was amended to preclude conscription as of July 1, 1973, Pub. L. 92-129, 85 Stat. 353, 50 U. S. C. App. § 467 (c), any actual conscription would require further congressional action. See S. Rep. No. 96-826, p. 155 (1980).
  Plaintiffs contended that the Act amounted to a taking of property without due process, imposed involuntary servitude, violated rights of free expression and assembly, was unlawfully implemented to advance an unconstitutional war, and impermissibly discriminated between males and females. The District Court denied plaintiffs’ application to convene a three-judge District Court and dismissed the suit, Rowland v. Tarr, 341 F. Supp. 339 (1972). On appeal, the Court of Appeals for the Third Circuit affirmed the dismissal of all claims except the discrimination claim, and remanded the case to the District Court to determine if this claim was substantial enough to warrant the convening of a three-judge court under then-applicable 28 U. S. C. §2282 (1970 ed.) and whether plaintiffs had standing to assert that claim. 480 F. 2d 545 (1973). On remand, the District Court answered both questions in the affirmative, resulting in the convening of the three-judge court which decided the case below. The Act authorizing three-judge courts to hear claims such as this was repealed in 1976, Pub. L. 94-381, §§ 1 and 2, 90 Stat. 1119, but remains applicable to suits filed before repeal, § 7, 90 Stat. 1120.
  As the Court stated in Schlesinger v. Ballard, 419 U. S. 498, 500, n. 3 (1975): “Although it contains no Equal Protection Clause as does the Fourteenth Amendment, the Fifth Amendment’s Due Process Clause prohibits the Federal Government from engaging in discrimination that is ‘so unjustifiable as to be violative of due process.’ Bolling v. Sharpe, 347 U. S. 497, 499.”
  When entering its judgment on July 18, the District Court redefined the class to include “[a] 11 male persons who are registered under 50 U. S. C. App. § 453 or are liable for training and service in the armed forces of the United States under 50 U. S. C. App. §§ 454, 456 (h) and 467 (c); and who are also either subject to registration under Presidential Proclamation No. 4771 (July 2, 1980) or are presently registered with the Selective Service System.” 509 F. Supp., at 605.
  See also Simmons v. United States, 406 F. 2d 456, 459 (CA5), cert, denied, 395 U. S. 982 (1969) (“That this court is not competent or empowered to sit as a super-executive authority to review the decisions of the Executive and Legislative branches of government in regard to the necessity, method of selection, and composition of our defense forces is obvious and needs no further discussion”).
  Congress recognized that its decision on registration involved judgments on military needs and operations, and that its decisions were entitled to particular deference: “The Supreme Court’s most recent teachings in the field of equal protection cannot be read in isolation from its opinions giving great deference to the judgment of Congress and military commanders in dealing [with] the management of military forces and the requirements of military discipline. The Court has made it unmistakably clear that even our most fundamental constitutional rights must in some circumstances be modified in the light of military needs, and that Congress’ judgment as to what is necessary to preserve our national security is entitled to great deference.” S. Rep. No. 96-826, pp. 159-160 (1980).
  Deference to Congress’ judgment was a consistent and dominant theme in lower court decisions assessing the present claim. See, e. g., United States v. Clinton, 310 F. Supp. 333, 335 (ED La. 1970); United States v. Offord, 373 F. Supp. 1117, 1118 (ED Wis. 1974).
  It is clear that “[g]ender has never been rejected as an impermissible classification in all instances.” Kahn v. Shevin, 416 U. S. 351, 356, n. 10 (1974). In making this observation the Court noted that “Congress has not so far drafted women into the Armed Services, 50 U. S. C. App. § 454.” Ibid.
  See Reinstitution of Procedures for Registration Under the Military Selective Service Act: Hearing on S. 109 and S. 226 before the Subcommittee on Manpower and Personnel of the Senate Committee on Armed Services, 96th Cong., 1st Sess. (1979) (Hearing on S. 109 and S. 226). Seven months before the President's call for the registration of women, the Senate Armed Services Committee rejected the idea, see S. Rep. No. 96-226, pp. 8-9 (1979).
  The amendment provided that no funds “shall be made available for implementing a system of registration which does not include women.” 126 Cong. Rec. 13876 (1980).
  The findings were before the conferees because the Senate Armed Services Committee had added a provision to the 1981 Defense Authorization Bill authorizing the transfer of funds to register young men as a stopgap measure should Joint Resolution 521 fail. See S. Conf. Rep. No. 96-895, at 100.
  Nor can we agree with the characterization of the MSSA in the Brief for National Organization for Women as Amicus Curiae as a law which “coerce[s] or preclude[s] women as a class from performing tasks or jobs of which they are capable,” or the suggestion that this case involves “[t]he exclusion of women from the military.” Id., at 19-20. Nothing in the MSSA restricts in any way the opportunities for women to volunteer for military service.
  No major country has women in combat jobs in their standing army. See App. 143.
  See Brief for Appellees 1-2, n. 2 (denying any concession of the validity of combat restrictions, but submitting restrictions are irrelevant to the present case). See also App. 256.
  Justice Marshall’s suggestion that since Congress focused on the need for combat troops in authorizing male-only registration the Court could “be forced to declare the male-only registration program unconstitutional,” post, at 96, in the event of a peacetime draft misreads our opinion. The perceived need for combat or combat-eligible troops in the event of a draft was not limited to a wartime draft. See, e. g., S. Rep. No. 96-826, at 157 (considering problems associated with “[registering women for assignment to combat or assigning women to combat positions in peacetime”) (emphasis supplied); id., at 158 (need for rotation between combat and noncombat positions “[i]n peace and war”).
  The grant of constitutional authority is, after all, to Congress and not to the Executive or military officials.
  The District Court also focused on what it termed Congress’ “inconsistent positions” in encouraging women to volunteer for military service and expanding their opportunities in the service, on the one hand, and exempting them from registration and the draft on the other. 509 F. Supp., at 603-604. This reasoning fails to appreciate the different purposes served by encouraging women volunteers and registration for the draft. Women volunteers do not occupy combat positions, so encouraging women to volunteer is not related to concerns about the availability of combat troops. In the event of a draft, however, the need would be for combat troops or troops which could be rotated into combat. See supra, at 76. Congress’ positions are clearly not inconsistent and in treating them as such the District Court failed to understand Congress’ purpose behind registration as distinguished from its purpose in encouraging women volunteers.
  General Rogers' testimony merits quotation:
  “General Rogers. One thing which is often lost sight of, Senator, is that in an emergency during war, the Army has often had to reach back into the support base, into the supporting elements in the operating base, and pull forward soldiers to fill the ranks in an emergency; that is, to hand them a rifle or give them a tanker suit and put them in the front ranks.
  “Senator WARNER. General Patton did that at one time, I believe at the Battle of the Bulge.
  “General Rogers. Absolutely.
  “Now, if that support base and that operating base to the rear consists in large measure of women, then we don’t have that opportunity to reach back and pull them forward, because women should not be placed in a forward fighting position or in a tank, in my opinion. So that, too, enters the equation when one considers the subject of the utility of women under contingency conditions."
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