OPINION OF THE COURT

HUTCHINSON, Circuit Judge.

By leave granted pursuant to 28 U.S.C.A. § 1292(b) (West 1993), Hoffmann-La Roche, Inc. ("Hoffmann-La Roche") appeals an interlocutory order of the United States District Court for the District of New Jersey. The district court's order granted a motion of former Hoffmann-La Roche employees to toll the statute of limitations in an age discrimination class action. Sperling claims Hoffmann-La Roche engaged in age discrimination against all similarly situated Hoffmann-La Roche employees in violation of the Age Discrimination in Employment Act ("ADEA"), 29 U.S.C.A. §§ 621-634 (West 1985 Supp. 1993). Tolling gave unnamed employees an opportunity to become members of the opt-in class that named appellees, Richard Sperling, Frederick Hemsley and Joseph Zelauskas (collectively "Sperling"), represent.

Class actions for age discrimination are authorized by section 7(b) of ADEA (codified as amended at 29 U.S.C.A. § 626(b)). Section 7(b) of ADEA expressly borrows the opt-in class mechanism of section 16(b) of the Fair Labor Standards Act of 1938 ("FLSA") (codified as amended at 29 U.S.C.A. § 216(b) (West Supp. 1993)). Section 16(b) of FLSA is itself modified by the Portal-to-Portal Act of 1947 (codified as amended at 29 U.S.C.A. §§ 251-262 (West 1985)). Section 6 of the Portal-to-Portal Act, 29 U.S.C.A. § 255, was expressly incorporated into ADEA until 1991. See 29 U.S.C.A. § 626(e)(1) (amended as of Nov. 21, 1991).

Section 7 of the Portal-to-Portal Act, 29 U.S.C.A. § 256, states an opt-in class member's claim for relief under FLSA does not commence until the date the opt-in member's written consent to join the representative action is filed. Section 7, unlike section 6 of the Portal-to-Portal Act, was not expressly incorporated into ADEA.

Over 400 persons filed consents to join Sperling's opt-in class within the limitations period, but 102 did not file consents until after expiration of unamended section 626(e)(1)'s two year statute of limitations on individual actions for non-willful violations of ADEA. Sperling contends these 102 consents were timely filed because the named plaintiffs' filing of a complaint in a representative action under ADEA legally tolls the statute of limitations. The district court agreed and granted Sperling's motion to legally toll the statute for the 102 persons whose individual actions would have been barred. See Sperling v. Hoffmann-La Roche, Inc., 145 F.R.D. 357, 366 (D.N.J. 1992).

Hoffmann-La Roche moved for interlocutory review of the legal tolling issue pursuant to 28 U.S.C.A. § 1292(b). The district court certified the following question to us pursuant to 28 U.S.C.A. § 1292(b):

[T]he issue of whether filing of the original complaint in this action tolled the statute of limitations for those plaintiffs who joined the action pursuant to this Court's Order dated January 5, 1988, involves a controlling question of law as to which there is a substantial ground for difference of opinion and an immediate appeal from the order may materially advance the ultimate termination of the litigation.

Joint Appendix ("App.") at 14A-15A. Hoffmann-La Roche thereafter filed a petition seeking our permission to appeal, as section 1292(b) requires. We granted its petition.

Whether an opt-in member in a class action can join a representative suit filed under ADEA after the statute of limitations on individual actions has run is a matter of first impression in our Court. We answer in the affirmative. Under ADEA we believe Congress did not intend to restrict opt-in classes to employees who file consents within the applicable statute of limitations that section 16(b) of FLSA and section 6 of the Portal-to-Portal Act set for individual age discrimination claims. To the contrary, we believe that Congress expressed its intent to permit additional members to opt-in and join the class by filing consents after the statute of limitations on their individual actions would have run when it omitted section 7 of the Portal-to-Portal Act from those portions of FLSA that it incorporated into ADEA's original statute of limitations. We therefore hold qualified plaintiffs may join a representative action for age discrimination after the time period for their individual actions has lapsed when the representative plaintiffs have filed a complaint within the statute of limitations set forth in section 6 of the Portal-to-Portal Act, provided, however, that the representatives have framed their complaint in a manner that puts the employer on notice that it will be called upon to defend an opt-in class action. Therefore, we will affirm the district court's order granting Sperling's motion to legally toll the statute of limitations and remand the case to the district court for further proceedings consistent with that order and our answer to the certified question this appeal presents.

I.

On February 4, 1985, Hoffmann-La Roche discharged or demoted about 1,200 employees in a systematic reduction of its work force. Sperling was one of them. He filed an age discrimination charge with the Equal Employment Opportunity Commission ("EEOC") on behalf of all similarly situated employees. On May 7, 1985, Sperling filed his representative action in the district court. The complaint alleged that Hoffmann-La Roche had engaged in unlawful age discrimination, clearly indicated its representative nature, and was filed within the then-applicable two year statute of limitations for non-willful violations of ADEA.

Sperling had already notified 600 potential plaintiffs and over 400 filed written consents within the two year statute of limitations applicable to their individual actions. To ensure that all potential plaintiffs would receive notice of the suit, Sperling moved for discovery of the names and addresses of all similarly situated employees and requested the court to send notice of the action to all potential class members in accordance with section 7(b) of ADEA, borrowed from section 16(b) of FLSA. The district court granted Sperling's motion on January 5, 1988 and required all consent forms to be filed with the court within a definite, limited time. See Sperling v. Hoffmann-La Roche, 145 F.R.D. 357, 358 (D.N.J. 1992). Both this Court and the United States Supreme Court subsequently affirmed this order. See Sperling v. Hoffmann-La Roche, Inc., 862 F.2d 439 (3d Cir. 1988), aff'd, 493 U.S. 165, 169-171, 110 S.Ct. 482, 486, 107 L.Ed.2d 480 (1989) (district court has discretion under ADEA to implement 29 U.S.C.A. § 216(b) by facilitating notice to potential plaintiffs who had not yet filed written consents to join).

In April 1990, notice of the pendency of this action was circulated to Hoffmann-La Roche's former employees. In response, within the time permitted by the district court's order but after the two year statute of limitations on their individual actions had expired, another 102 persons filed consents to join Sperling's representative action. In September 1991, Sperling asked the district court to hold that these 102 consents were timely filed because the complaint in the representative action legally tolled the statute of limitations under ADEA. The district court referred the matter to a Special Master. The Special Master recommended granting Sperling's motion to join or incorporate into the opt-in class the 102 persons who filed consents in accordance with the procedure the district court established in its order after the statute would have run on their individual actions.

The district court adopted the Special Master's recommendation and granted Sperling's motion for legal tolling. See Sperling, 145 F.R.D. at 366. It concluded "[a]nalysis of the statutory scheme of ADEA, the existing case law, and the policies and goals underlying class actions and statutes of limitations, persuades me to find that the best resolution of this issue is that the statute of limitations is tolled in ADEA class actions." Id. at 360. It rejected Hoffmann-La Roche's argument that section 7 of the Portal-to-Portal Act was implicitly incorporated into unamended section 7(e) of ADEA along with section 6 of the Portal-to-Portal Act's incorporation. Instead, the district court reasoned that Congress intended to incorporate only certain provisions of section 16(b) of FLSA, as amended by the Portal-to-Portal Act, into ADEA. Id. at 361. Section 6 of the Portal-to-Portal Act was expressly incorporated while section 7 of that Act was not. Id.

The district court did not base its decision solely on the selective incorporation theory. It also recognized that ADEA

does share some procedural similarities with the FLSA, [but] it also shares many similarities with Title VII, which is governed by Rule 23. . . . Thus, it is reasonable that Congress intended the tolling rule applicable to Title VII cases to apply, rather than the non-tolling rule of Section 256 of the FLSA. Courts have looked to and applied other Title VII procedural aspects to ADEA class actions.

Id. (citations omitted). According to the district court, legal tolling in ADEA cases is consistent with the goals of any statute of limitations — to provide notice to defendants of claims against them and to discourage plaintiffs from sleeping on their rights. Id. at 364. In addition, the district court described some of the practical problems that would ensue if tolling were not permitted. Sperling filed the complaint on May 7, 1985, three months after the alleged discriminatory act occurred. The district court did not grant Sperling's motion for court-authorized service of notice until January 1988, almost three years after the alleged unlawful conduct. Under Hoffmann-La Roche's interpretation, the statute of limitations would have expired before the court had authorized service of notice on putative members of the opt-in class. Id. at 365.

After the district court handed down its order, Hoffmann-La Roche moved to certify the legal tolling issue for interlocutory appeal pursuant to 28 U.S.C.A. § 1292(b). The district court granted permission for an interlocutory appeal and a motions panel of this Court granted Hoffmann-La Roche's petition for permission to appeal pursuant to 28 U.S.C.A. § 1292(b).

II.

This case is a private, representative action authorized by section 7(b) of ADEA. The district court had subject matter jurisdiction under 28 U.S.C.A. § 1331 (West 1993). We have appellate jurisdiction over the district court's order granting Sperling's motion for legal tolling under 28 U.S.C.A. § 1292(b).

Whether a consent to opt-in must be filed by a class member who wishes to participate in an ADEA class action within the same time limit he or she has to file an individual complaint is a question of law. Accordingly, our review of the district court's decision is plenary. See Gavalik v. Continental Can Co., 812 F.2d 834, 850 (3d Cir.), cert. denied, 484 U.S. 979, 108 S.Ct. 495, 98 L.Ed.2d 492 (1987); Chrysler Credit Corp. v. First Nat'l Bank Trust Co., 746 F.2d 200, 202 (3d Cir. 1984) (per curiam). As stated earlier, the question presented is also a matter of first impression in this Court.

III.

Our holding that ADEA's statute of limitations is tolled for eligible class members by the initial filing of a representative complaint, as long as the representative nature of the action is clear on the complaint's face, is foreshadowed by our opinion in Lusardi v. Lechner, 855 F.2d 1062, 1077-78 (3d Cir. 1988). There we listed with approval decisions in other courts that had allowed individuals who had not filed timely administrative charges to participate in an ongoing representative suit.

A.

In ADEA, Congress borrowed portions of many other statutes. It incorporated parts of FLSA, parts of the Portal-to-Portal Act, and parts of Title VII of the Civil Rights Act of 1964, 42 U.S.C.A. §§ 2000e to 2000e-17 (West 1981 Supp. 1993). Each of these acts employs one of two types of class actions as aids to enforcement: the opt-out representative action permitted by Federal Rule of Civil Procedure 23(b)(3) and the opt-in representative action authorized by section 16(b) of FLSA. Analysis of the district court's order permitting persons to opt-in after their individual actions could have been barred by limitations requires a brief review of these two types of class actions.

The opt-in class action that section 16(b) of FLSA permits has its antecedents in the old equity Bill of Peace, a device Chancellors once used to join numerous parties with common interests so that their common claims could be disposed of efficiently in one suit. See Ellen E. Sward, Values, Ideology and the Evolution of the Adversary System, 64 Ind. L.J. 301, 331 (1989). In its inception, the Bill of Peace was a response to the strict limits the common law placed on joinder of parties, though only the representative parties were named. The modern opt-out class action also evolved out of the joinder mechanism of the old Bill of Peace, but it no longer has any easily perceptible traces of its antecedents in permissive joinder. The opt-out class action is governed by Federal Rule of Civil Procedure 23(b)(3), which differs in important respects from the opt-in class permitted by section 16(b) of FLSA. See, e.g., Fed.R.Civ.P. 23(c)(3) (a class action judgment is binding on all class members "who have not requested exclusion"). Thus, if a person does not wish to be bound by an order in a Rule 23 class action he must specifically ask to be excluded.

While ADEA's opt-in class action is not governed by Federal Rule of Civil Procedure 23(b)(3), class actions brought under Title VII are governed by the opt-out provisions of Rule 23. See Edwards v. Boeing Vertol Co., 717 F.2d 761, 765-66 (3d Cir. 1984), vacated, 468 U.S. 1201, 104 S.Ct. 3566, 82 L.Ed.2d 867, reinstated, 750 F.2d 13 (3d Cir. 1984). The law on limitations in Rule 23 actions is settled. In American Pipe Construction Co. v. Utah, 414 U.S. 538, 94 S.Ct. 756, 38 L.Ed.2d 713 (1974), the Supreme Court recognized that the claims of all class members under Rule 23 are protected by the filing of an original, timely complaint. See American Pipe, 414 U.S. at 551, 94 S.Ct. at 765. The complaint in American Pipe alleged a violation of section 1 of the Sherman Act, 15 U.S.C.A. § 1 (West Supp. 1994). The Supreme Court held individual satisfaction of the statute of limitations is not required in Rule 23 class actions because:

[T]he difficulties and potential for unfairness which, in part, convinced some courts to require individualized satisfaction of the statute of limitations by each member of the class, have been eliminated, and there remain no conceptual or practical obstacles in the path of holding that the filing of a timely class action complaint commences the action for all members of the class as subsequently determined. Whatever the merit in the conclusion that one seeking to join a class after the running of the statutory period asserts a "separate cause of action" which must individually meet the timeliness requirements, such a concept is simply inconsistent with Rule 23 as presently drafted. A federal class action is no longer "an invitation to joinder" but a truly representative suit designed to avoid, rather than encourage, unnecessary filing of repetitious papers and motions.

American Pipe, 414 U.S. at 550, 94 S.Ct. at 765 (footnote and citation omitted). The rule tolling the statute of limitations when the class action complaint is filed is commonly referred to as the " American Pipe rule." See Korwek v. Hunt, 827 F.2d 874, 878 (2d Cir. 1987); Fernandez v. Chardon, 681 F.2d 42, 48 (1st Cir. 1982), aff'd, 462 U.S. 650, 103 S.Ct. 2611, 77 L.Ed.2d 74 (1983).

When class relief is sought pursuant to section 16(b) of FLSA, as modified by section 7 of the Portal-to-Portal Act, the rule governing the timeliness of an opt-in class member's consent to join a class is different. By section 7 of the Portal-to-Portal Act, all class members who seek relief under FLSA must submit their affidavits of consent before the statute of limitations applying to their individual claims has run. In the early case of Gibbons v. Equitable Life Assurance Society of United States, 173 F.2d 337, 339 (2d Cir. 1949), the court stated "[t]he terms of the Portal-to-Portal Act indicate that one of its aims was to prevent the assertion of surprise claims by unnamed employees at a time when the statute of limitations would otherwise have run." Id.; see also 29 U.S.C.A. §§ 255-256.

The restrictive provisions of the Portal-to-Portal Act were thought necessary to control what Congress viewed as the virtually unlimited liability generated by the United States Supreme Court's decision in Anderson v. Mt. Clemens Pottery Co., 328 U.S. 680, 66 S.Ct. 1187, 90 L.Ed. 1515 (1946). In Mt. Clemens, the Supreme Court held an employer was responsible for paying an employee from "portal-to-portal," that is, from the time he arrived at work until the time he left, including the time it took for him to get to and from the time clock to his actual job site. Id. at 690-92, 66 S.Ct. at 1193-94. The Supreme Court's decision, which was unexpected by industry, led employers to fear huge damages because FLSA had no express statute of limitations. The flood of claims Mt. Clemens was thought likely to generate also caused the government to fear large enforcement costs. Congress's reaction to Mt. Clemens was the Portal-to-Portal Act. Its legislative history reflects these concerns:

The uncertainty of the present situation with its tremendous threat is seriously interfering with efforts to return to a peace-time economy with full and efficient production; it has clogged the courts with new and expensive litigation; it interferes with the right of collective bargaining; it threatens to add greatly to the cost of goods and services bought by the Government, while at the same time reducing the Federal revenue; it is a serious burden on interstate commerce.

House Comm. on the Judiciary, Portal-to-Portal Act of 1947, H.R.Rep. No. 71, 80th Cong., 1st Sess., reprinted in 1947 U.S.Code Cong.Serv. 1029, 1034. Thus, when Congress enacted the Portal-to-Portal Act of 1947, one year after Mt. Clemens, it severely restricted the claims an employee could make for back wages by various means, including a strict statute of limitations.

The representative mechanism Congress created for use in age discrimination cases differs from both the Rule 23 class action used in Title VII and the more restrictive representative action FLSA permits. These differences seem clear from the language of ADEA as well as its legislative history.

Congress did not incorporate all the class action provisions of FLSA and the Portal-to-Portal Act into ADEA, nor did it add an age discrimination cause of action to either FLSA or Title VII. Indeed, Congress declined to adopt a bill that would have amended FLSA to bring age discrimination within its prohibitions. See Levine v. Bryant, 700 F. Supp. 949, 952 (N.D.Ill. 1988) (quoting s. 788, 90th Cong., 1st Sess. (1967), reprinted in, 113 Cong.Rec. 2199 (1967)). Instead, Congress pieced ADEA together by selectively incorporating into it specific parts both of Title VII and FLSA. ADEA is the offspring of these two parents, but the mixture of traits it has inherited from each gives it its own individuality.

Congress was precise in selecting the portions of other acts that were to comprise ADEA. Only specific subsections of FLSA, the Portal-to-Portal Act and Title VII were incorporated. Among those left out was section 7 of the Portal-to-Portal Act, one of the restrictive clauses which Congress felt was needed to stem the tide of litigation it feared would otherwise follow the decision in Mt. Clemens.

The opt-out class mechanism of Rule 23(b)(3) and (c)(2) was also excluded by Congress's incorporation of the opt-in provisions of section 16(b) of FLSA. Thus, age discrimination plaintiffs must affirmatively express their desire to join a pending representative action. The converse is true under Rule 23(c)(2). Members of a Rule 23(b)(3) class are automatically included and remain so unless they make a timely election to opt-out. On the other hand, "the prohibitions of the [ADEA] were derived in haec verba from Title VII." Lorillard v. Pons, 434 U.S. 575, 584, 98 S.Ct. 866, 872, 55 L.Ed.2d 40 (1978).

We see nothing in either the unamended statutory text or the legislative history of ADEA that indicates we should incorporate section 7 of the Portal-to-Portal Act's restrictions into it. Indeed, we think this would be inconsistent with both the Act's text, as it appeared prior to 1991, and Congress's intent. Cf. Lorillard, 434 U.S. at 581-82, 98 S.Ct. at 871. We are not persuaded to the contrary by O'Connell v. Champion International Corp., 812 F.2d 393 (8th Cir. 1987). There the court, considering only Federal Rule of Civil Procedure 15's relation-back doctrine, stated:

The District Court held, and we agree, that the relation-back doctrine must yield in ADEA cases to the specific provision of 29 U.S.C. § 256 that an action may be commenced only by the filing of a complaint by the named individual, or by his affirmatively opting into a previously commenced class action.

Id. at 394. The O'Connell court did not expand on its reasoning or consider the possibility that Congress's refusal to incorporate section 7 of the Portal-to-Portal Act into ADEA was an indication that ADEA's statute of limitations, taken verbatim from section 6 of the Portal-to-Portal Act, should be tolled for the benefit of persons who opt-in to a timely filed representative action.

We are bound by the intent of Congress, as we perceive it. In deciding to borrow parts of FLSA's statute of limitations for ADEA, Congress refused to carry over section 7 of the Portal-to-Portal Act requiring class members who desire to opt-in to representative actions brought under FLSA to do so within the time limits imposed on individual claims. Instead, it chose to incorporate only section 6's limitations on individual claims. Its incorporation of selected provisions into section 7(b) of ADEA indicates that Congress deliberately left out those provisions not incorporated. See Morelock v. NCR Corp., 586 F.2d 1096, 1103 (6th Cir. 1978) (noting that 29 U.S.C.A. § 256 is not applicable to age discrimination suits because Congress did not incorporate it into ADEA), cert. denied, 441 U.S. 906, 99 S.Ct. 1995, 60 L.Ed.2d 375 (1979). Indeed, the decision we make today strikes us as a fairly routine application of the traditional rule of statutory construction pithily captured in the Latin maxim expressio unius est exclusio alterius. Thus, as the Court explained in Continental Casualty Co. v. United States, 314 U.S. 527, 533, 62 S.Ct. 393, 396, 86 L.Ed. 426 (1942), "[g]enerally speaking a 'legislative affirmative description' implies denial of the non-described powers." Id. This maxim takes on more life in ADEA because of the thorough legislative understanding of the law in this area when Congress enacted ADEA. As the Supreme Court stated:

[I]n enacting the ADEA, Congress exhibited both a detailed knowledge of the FLSA provisions and their judicial interpretation and a willingness to depart from those provisions regarded as undesirable or inappropriate for incorporation.

Lorillard, 434 U.S. at 581, 98 S.Ct. at 870 (Congress intended trial by jury to be available in private actions under ADEA).

In Trans World Airlines, Inc. v. Thurston, 469 U.S. 111, 105 S.Ct. 613, 83 L.Ed.2d 523 (1985), the Supreme Court precluded judges from reading into ADEA section of FLSA Congress had left out. There, the Supreme Court refused to imply incorporation of FLSA's limits on liquidated damages into ADEA absent specific incorporation by Congress. Id. at 128 n. 22, 105 S.Ct. at 625 n. 22. Here, the two and three year statutes of limitations in section 6 of the Portal-to-Portal Act had been expressly incorporated into ADEA, but section 7 of the Portal-to-Portal Act, requiring persons desiring to opt-in to a representative action to do so within the time limit FLSA imposes on individual actions, was never expressly incorporated. Thus, under a selective incorporation theory, we must reject Hoffmann-La Roche's argument that legal tolling would be contrary to the intent of Congress.

Moreover, the special problems of open-ended unanticipated claims that Mt. Clemens created are not present under ADEA so long as both the charge and the complaint put the employer on notice that class relief will be sought.

B.

An opt-in class action under ADEA is more than a device for the permissive joinder of parties. Hoffmann-La Roche's argument that the opt-in procedure of section 16(b) of FLSA is a substitute for permissive intervention and therefore that Federal Rule of Civil Procedure 24(b) provides an appropriate analogy for determination of the timeliness of a consent to a representative action under ADEA is not persuasive. Hoffmann-La Roche's argument that Rule 24 applies is only a variation on the equally unpersuasive argument that incorporation of section 16(b) of FLSA into ADEA incorporates Rule 20's rules on permissive joinder. We rejected this analogy to permissive joinder under Rule 20 in our earlier decision in this case. See Sperling, 862 F.2d at 446. There we stated "that [ § 16(b)] does more than create the right of permissive joinder already provided by Rule 20 of the Federal Rules of Civil Procedure." Id. (citation omitted); see also Lusardi, 855 F.2d at 1078 (rejecting section 16(b)'s analogy to either permissive joinder or intervention).

We think a representative action brought under ADEA is commenced on behalf of all consenting class members when the original representative complaint is filed. See Fed.R.Civ.P. 3 ("A civil action is commenced by filing a complaint with the court."). It has already been firmly settled, in the context of Rule 23 class actions, that "a tolling rule for class actions is not inconsistent with the purposes served by statutes of limitations." See Crown, Cork Seal Co., v. Parker, 462 U.S. 345, 352, 103 S.Ct. 2392, 2397, 76 L.Ed.2d 628 (1983). We think application of principles of legal tolling to a class action for age discrimination is also consistent with the three basic purposes a statute of limitations serves. They are first a "practical and pragmatic device to spare the courts from litigation of stale claims, and the citizen from being put to his defense after memories have faded, witnesses have died or disappeared, and evidence has been lost." Mills v. Habluetzel, 456 U.S. 91, 101 n. 9, 102 S.Ct. 1549, 1556 n. 9, 71 L.Ed.2d 770 (1982) (quoting Chase Sec. Corp. v. Donaldson, 325 U.S. 304, 314, 65 S.Ct. 1137, 1142, 89 L.Ed. 1628 (1945)). So long as the initial complaint is timely, a claim, by definition, is not stale. Secondly, "[l]imitations periods are intended to put defendants on notice of adverse claims." Crown, Cork Seal, 462 U.S. at 352, 103 S.Ct. at 2397. Finally, limitations periods "prevent plaintiffs from sleeping on their rights." Id. When filed within the statute of limitations, the original representative complaint, as long as it shows on its face its representative nature, tolls the running of the statute of limitations. It provides an employer reasonable notice of the claim for class relief. When a complaint clearly indicates the claim's representative nature, the employer is put on notice that it faces a broader and potentially more serious problem than an individual action would create.

Rule 23(d) then allows a district court to prevent abusive tolling extensions through its case management power. See Sperling, 493 U.S. at 169, 110 S.Ct. at 486 (noting that "once an ADEA action is filed, the court has a managerial responsibility to oversee the joinder of additional parties to assure that the task is accomplished in an efficient and proper way"). Tolling the statute of limitations once the representative complaint is filed also allows distribution of notice to potential plaintiffs to proceed while the question of class certification is pending. Potential plaintiffs are made aware of their rights. If the district court, pursuant to its case management powers, promptly sets a reasonable cut-off date for closing the opt-in class, the scope of the suit is limited and made known to the defendant employer within a reasonable time after the claim seeking class relief is filed. Such a controlled tolling of ADEA's statute of limitations seems to us to accomplish fully the intent of Congress without inflicting any untoward inequity on an employer who knows before the statute runs that he is dealing with a representative class action.

IV.

Accordingly, in answer to the question certified, we hold that the filing of the original complaint tolled the applicable two year statute of limitations for those plaintiffs who joined the action after the limitations period for their individual actions had run. Section 7 of the Portal-to-Portal Act cannot be used to limit the time within which persons "similarly situated" to a representative plaintiff who has filed a timely complaint for age discrimination may opt-in to an ADEA representative class action. Legal tolling is consistent in this case with the purposes behind a statute of limitations. The district court's order granting Sperling's motion for legal tolling will be affirmed and the case remanded to it for further proceedings consistent with this opinion.