OPINION OF THE COURT
Laura Symezyk sought relief under the Fair Labor Standards Act (FLSA), 29 U.S.C. §§ 207 and 216(b), on behalf of herself and all others similarly situated. The District Court for the Eastern District of Pennsylvania dismissed Symczyk’s complaint for lack of subject matter jurisdiction after defendants Genesis Healthcare Corporation and ElderCare Resources Corporation extended an offer of judgment under Fed.R.Civ.P. 68 in full satisfaction of her alleged damages, fees, and costs. At issue in this case is whether a collective action brought under § 216(b) of the FLSA becomes moot when, prior to moving for “conditional certification” and prior to any other plaintiff opting in to the suit, the putative representative receives a Rule 68 offer. We will reverse and remand.
I.
From April 2007 through December 2007, Symezyk was employed by defendants as a Registered Nurse at Pennypack Center in Philadelphia, Pennsylvania. On December 4, 2009, Symezyk initiated a collective action under 29 U.S.C. § 216(b) on behalf of herself and all similarly situated individuals, alleging defendants violated the FLSA when they implemented a policy subjecting the pay of certain employees to an automatic meal break deduction whether or not they performed compensable work during their breaks. 1 On February 18, 2010, defendants filed an answer to Symczyk’s complaint and served her with an offer of judgment under Fed.R.Civ.P. 68 in the amount of “$7,500.00 in alleged unpaid wages, plus attorneys’ fees, costs and expenses as determined by the Court.” 2 Symezyk did not dispute the *191 adequacy of defendants’ offer but nevertheless declined to respond.
The District Court — unaware of the offer of judgment — held a Fed.R.Civ.P. 16 scheduling conference on March 8, 2010. Two days later, the court entered a scheduling order providing for “an initial ninety (90) day discovery period, at the close of which [Symczyk] will move for conditional certification under § 216(b) of the FLSA.” Following the court’s ruling on certification, the parties were to have “an additional six (6) month discovery period, to commence at the close of any Court-ordered opt-in window.”
On March 23, 2010, defendants filed a motion to dismiss for lack of subject matter jurisdiction under Fed.R.Civ.P. 12(b)(1), contending that, because Symczyk had effectively rejected their Rule 68 offer of judgment, see Fed.R.Civ.P. 68(a) (providing a plaintiff with 14 days to accept an offer), she “no longer ha[d] a personal stake or legally cognizable interest in the outcome of this action, a prerequisite to this Court’s subject matter jurisdiction under Article III of the United States Constitution.” Symczyk objected, citing defendants’ strategic attempt to “pick off’ the named plaintiff before the court could consider her “certification” motion. 3
On May 19, 2010, the District Court “tentatively concluded” that defendants’ Rule 68 offer mooted the collective action and that the action should be dismissed for lack of subject matter jurisdiction.
Symczyk v. Genesis Healthcare Corp.,
No. Civ. A 09-5782,
Symczyk does not contend that other individuals have joined her collective action. Thus, this case, like each of the district court cases cited by Defendants, which concluded that a Rule 68 offer of judgment mooted the underlying FLSA collective action, involves a single named plaintiff. In addition, Symczyk does not contest Defendants’ assertion that the 68 offer of judgment fully satisfied her claims....
Id.
at *4,
*192 II.
A.
Enacted in 1938, the FLSA, 29 U.S.C. § 201
et seq.,
was designed “to aid the unprotected, unorganized and lowest paid of the nation’s working population; that is, those employees who lacked sufficient bargaining power to secure for themselves a minimum subsistence wage.”
Brooklyn Sav. Bank v. O’Neil,
Prior to 1947, the FLSA permitted an aggrieved employee to “designate an agent or representative to maintain such action for and in behalf of all employees similarly situated.”
Martino v. Mich. Window Cleaning Co.,
In deciding whether a suit brought under § 216(b) may move forward as a collective action, courts typically employ a two-tiered analysis. During the initial phase, the court makes a preliminary determination whether the employees enumerated in the complaint can be provisionally categorized as similarly situated to the named plaintiff. If the plaintiff carries her burden at this threshold stage, the court will “conditionally certify” the collective action for the purposes of notice and pretrial discovery. In the absence of statutory guidance or appellate precedent on the proper definition of “similarly situated,” a divergence of authority has emerged on the level of proof required at this stage. Some trial courts within our circuit have allowed a plaintiff to satisfy her burden simply by making a “substantial allegation” in her pleadings that she and the prospective party plaintiffs suffered from a single decision, plan or policy, but the majority of our circuit’s trial courts have required the plaintiff to make a “modest factual showing” that the proposed recipients of opt-in notices are similarly situat
*193
ed.
See Wright v. Lehigh Valley Hosp.,
No. Civ. A 10-431,
Under the “modest factual showing” standard, a plaintiff must produce some evidence, “beyond pure speculation,” of a factual nexus between the manner in which the employer’s alleged policy affected her and the manner in which it affected other employees.
See Smith v. Sovereign Bancorp, Inc.,
No. 03-2420,
After discovery, and with the benefit of “a much thicker record than it had at the notice stage,” a court following this approach then makes a conclusive determination as to whether each plaintiff who has opted in to the collective action is in fact similarly situated to the named plaintiff.
Morgan v. Family Dollar Stores, Inc.,
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Absent from the text of the FLSA is the concept of “class certification.” As the Eighth Circuit has noted, however, “[m]any courts and commentators ... have used the vernacular of the Rule 28 class action for simplification and ease of understanding when discussing representative cases brought pursuant to § 16(b) of the FLSA.”
Kelley v. Alamo,
Despite this judicial gloss on § 216(b), “the ‘certification’ we refer to here is only the district court’s exercise of [its] discretionary power, upheld in
Hojfmann-La Roche,
to facilitate the sending of notice to potential class members,” and “is neither necessary nor sufficient for the existence of a representative action under FLSA.”
Myers v. Hertz Corp.,
B.
Article III of the United States Constitution limits the jurisdiction of the federal
*195
courts to “actual ‘Cases’ and ‘Controversies.’ ”
Sprint Commc’ns Co. v. APCC Servs., Inc.,
Rule 68 was designed “to encourage settlement and avoid litigation.”
Marek v. Chesny,
Requiring multiple plaintiffs to bring separate actions, which effectively could be ‘picked off by a defendant’s tender of judgment before an affirmative ruling on class certification could be obtained, obviously would frustrate the objectives of class actions; moreover it would invite waste of judicial resources by stimulating successive suits brought by others claiming aggrievement.
Deposit Guar. Nat’l Bank v. Roper,
We addressed the tension between Rules 23 and 68 in
Weiss.
There, the named plaintiff filed a federal class action complaint alleging violations of the Fair Debt Collection Practices Act, 15 U.S.C. § 1692, and, prior to moving for class certification, received a Rule 68 offer of judgment in full satisfaction of the individual relief sought. The plaintiff rejected the offer, and the court granted the defendants’ 12(b)(1) motion to dismiss the complaint on mootness grounds. On appeal, we explored the applicability of the “relation back” doctrine to a scenario in which the defendants’ “tactic of picking off lead plaintiffs with a Rule 68 offer ... may deprive a representative plaintiff the opportunity to timely bring a class certification motion, and also may deny the court a reasonable opportunity to rule on the motion.”
In essence, the relation back doctrine allows a district court to retain jurisdiction over a matter that would appear susceptible to dismissal on mootness grounds by virtue of the expiration of a named plaintiffs individual claims. In
Sosna v. Iowa,
This equitable principle has evolved to account for calculated attempts by some defendants to short-circuit the class action process and to prevent a putative representative from reaching the certification stage. Certification vests a named plaintiff with a procedural right to act on behalf of the collective interests of the class that exists independent of his substantive claims.
See Sosna,
Normally, ... a class action must be certified as such in order for it to escape dismissal once the claims of the named plaintiff become moot. But the courts have recognized that an absolute requirement would prevent some otherwise justiciable claims from ever being subject to judicial review.... [JJust as necessity required the development of the relation back doctrine in cases where the underlying factual situation naturally changes so rapidly that the courts cannot keep up, so necessity compels a similar result here. If the class action device is to work, the courts must have a reasonable opportunity to consider and decide a motion for certification. If a tender made to the individual plaintiff while the motion for certification is pending could prevent the courts from ever reaching the class action issues, that opportunity is at the mercy of a defendant, even in cases where a class action would be most clearly appropriate.
Susman v. Lincoln Am. Corp.,
When a defendant’s Rule 68 offer threatens to preempt the certification process, reconciling the conflicting imperatives of Rules 23 and 68 requires allocating sufficient time for the process to “play out.”
Weiss,
III.
A.
The issue we must resolve on this appeal, then, is whether an FLSA collective action becomes moot when (1) the putative representative receives a Rule 68 offer in full satisfaction of her individual claim prior to moving for “conditional certification,” and (2) no other potential plaintiff has opted in to the suit.
9
Animating our decision in
Weiss
was the ability of defendants to use Rule 68 “to thwart the putative class action before the certification question could be decided.”
In support of their effort to confíne
Weiss
to the class action setting, defendants rely principally on the dissimilar roles played by Rule 23 and § 216(b) named plaintiffs. As noted, the statutory form of aggregation provided for in the FLSA requires each party plaintiff affirmatively to opt in to a collective action by filing a consent form “in the court in which such action is brought.” 29 U.S.C. § 216(b). Whereas a member of a certified class in a Rule 23(b)(3) proceeding will be bound by judgment unless he has intentionally opted out of the suit, resolution of a § 216(b) collective action will not bind any similarly situated employee absent his express, written consent.
See id.; LaChapelle v. Owens-Illinois, Inc.,
Although defendants’ logic has some surface appeal, reliance on the watershed event of an opt-in to trigger application of the special mootness rules that prevail in the representative action context ineentivizes the undesirable strategic use of Rule 68 that prompted our holding in Weiss.
12
As the Supreme Court explained in
Hoffmanfir-La Roche,
actualization of § 216(b)’s purposes often necessitates a
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district court’s engagement at the notice phase of the proceeding.
In
Sandoz,
the only court of appeals’ decision to address the applicability of the relation back doctrine in the FLSA context, the Fifth Circuit concluded Congress did not intend, through the enactment of § 216(b), to create an “anomaly” by allowing employers “to use Rule 68 as a sword, ‘picking off representative plaintiffs and avoiding ever having to face a collective action.”
[T]he differences between class actions and FLSA § 216(b) collective actions do not compel a different result regarding whether a certification motion can “relate back” to the filing of the complaint. The status of a case as being an “opt in” or “opt out” class action has no bearing on whether a defendant can unilaterally moot a plaintiffs case through a Rule 68 offer of judgment. Although the differences between Rule 23 class actions and FLSA § 216(b) collective actions alter the conceptual mootness inquiry, each type of action would be rendered a nullity if defendants could simply moot the claims as soon as the representative plaintiff files suit. Thus, the policies behind applying the “relation back” principle for Rule 23 class actions apply with equal force to FLSA § 216(b) collective actions.
Id.
at 920 (citations omitted). There, the defendant tendered its offer of judgment approximately one month after Sandoz had commenced her FLSA action, and Sandoz waited thirteen months after filing her complaint to move for “conditional certification.”
Id.
at 921. Borrowing language from
Weiss
and holding that “relation back is warranted only when the plaintiff files for certification without undue delay,’ ”
id.
(quoting
Weiss,
B.
Although the opt-in mechanism transforms the manner in which a named plaintiff acquires a personal stake in representing the interests of others, it does not present a compelling justification for limiting the relation back doctrine to the Rule 23 setting. The considerations that caution against allowing a defendant’s use of Rule 68 to impede the advancement of a representative action are equally weighty in either context. Rule 23 permits plaintiffs “to pool claims which would be uneconomical to litigate individually.”
Phillips Petroleum Co. v. Shutts,
When Rule 68 morphs into a tool for the strategic curtailment of representative actions, it facilitates an outcome antithetical to the purposes behind § 216(b). Symczyk’s claim — like that of the plaintiff in
Weiss
— was “acutely susceptible to mootness” while the action was in its early stages and the court had yet to determine whether to facilitate notice to prospective plaintiffs.
See Weiss,
C.
Additionally, the relation back doctrine helps safeguard against the erosion of FLSA claims by operation of the Act’s statute of limitations. To qualify for relief under the FLSA, a party plaintiff must “commence” his cause of action before the statute of limitations applying to his individual claim has lapsed.
Sperling v. Hoffmann-La Roche, Inc.,
D.
In sum, we believe the relation back doctrine helps ensure the use of Rule 68 does not prevent a collective action from playing out according to the directives of § 216(b) and the procedures authorized by the Supreme Court in
Hoffmann-La
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Roche
and farther refined by courts applying this statute. Depriving the parties and the court of a reasonable opportunity to deliberate on the merits of collective action “conditional certification” frustrates the objectives served by § 216(b).
Cf. Sandoz,
Upon remand, should Symczyk move for “conditional certification,” the court’ shall consider whether such motion was made without undue delay, and, if it so finds, shall relate the motion back to December 4, 2009 — the date on which Symczyk filed her initial complaint. If (1) Symczyk may yet timely seek “conditional certification” of her collective action, (2) the court permits the case to move forward as a collective action (by virtue of Symezyk’s satisfaction of the “modest factual showing” standard), and (3) at least one other similarly situated employee opts in, then defendants’ Rule 68 offer of judgment would no longer fully satisfy the claims of everyone in the collective action, and the proffered rationale behind dismissing the complaint on jurisdictional grounds would no longer be applicable. If, however, the court finds Symezyk’s motion to certify would be untimely, or otherwise denies the motion on its merits, then defendants’ Rule 68 offer to Symczyk — in full satisfaction of her individual claim — would moot the action.
IV.
For the foregoing reasons, we will reverse the judgment of the District Court and remand for proceedings consistent with this opinion.
Notes
. Symczyk’s amended complaint identified those "similarly situated” as
All persons employed within the three years preceding the filing of this action by Defendants ..., whose pay was subject to an automatic 30 minute meal period deduction even when they performed compensable work during the unpaid "meal break”.... These persons include, but are not limited to, secretaries, housekeepers, custodians, clerks, porters, registered nurses, licensed practical nurses, nurses’ aides, administrative assistants, anesthetists, clinicians, medical coders, medical underwriters, nurse case managers, nurse interns, nurse practitioners, practice supervisors, professional staff nurses, quality coordinators, resource pool nurses, respiratory therapists, senior research associates, operating room coordinators, surgical specialists, admissions officers, student nurse technicians, trainers, and transcriptionists employed at any of Defendants’ facilities during the three years preceding the filing of this action.
. In part, Fed.R.Civ.P. 68 provides:
(a) At least 14 days before the date set for trial, a party defending against a claim may serve on an opposing party an offer to allow judgment on specified terms, with the costs then accrued. If, within 14 days after be *191 ing served, the opposing party serves written notice accepting the offer, either party may then file the offer and notice of acceptance, plus proof of service. The clerk must then enter judgment.
(b) An unaccepted offer is considered withdrawn, but it does ■ not preclude a later offer. Evidence of an unaccepted offer is not admissible except in a proceeding to determine costs.
. On March 29, 2010, defendants removed Symczyk's related state-court action to the United States District Court for the Eastern District of Pennsylvania. Thereafter, on April 13, 2010, the parties jointly filed a proposed stipulated order providing Symczyk would voluntarily dismiss her related state-law action and amend her complaint in this action to include those state-law claims asserted in the related action. The District Court entered the parties' stipulated order on April 15, 2010, and Symczyk filed an amended class/collective action complaint on April 23, 2010.
. Prior to dismissing the action, the District Court had subject matter jurisdiction under
*192
28
U.S.C. § 1331 and 29 U.S.C. § 216(b). We exercise appellate jurisdiction pursuant to 28 U.S.C. § 1291. Our review of the court’s order granting defendants' motion to dismiss for lack of subject matter jurisdiction is plenary.
Gould Elecs., Inc. v. United States, 220
F.3d 169, 176 (3d Cir.2000). Because defendants' motion to dismiss was based on facts outside the pleadings (i.e., their Rule 68 offer of judgment), the trial court was entitled to weigh and evaluate the evidence bearing on the jurisdictional dispute.
Mortensen v. First Fed. Sav. & Loan Ass’n,
. Although this two:step approach is nowhere mandated, it appears to have garnered wide acceptance. And, while courts retain broad discretion in determining whether to “conditionally certify” a collective action, it is useful to prescribe a uniform evidentiary standard.
Cf. In re Hydrogen Peroxide Antitrust Litig.,
This case illustrates how an uncertain standard may work to the detriment of § 216(b) plaintiffs. Here, the court — unaware of defendants' Rule 68 offer — issued a case management order allotting Symczyk “an initial ninety (90) day discovery period” to compile evidence before she would be expected to move for "conditional certification.” Symczyk represents she considered the standard for "conditional certification” a "moving target in our circuit” and requested discovery in order to buttress the allegations in her pleadings with sufficient evidence to make a "meaningful motion” at this initial stage. Because defendants' Rule 68 offer preceded the commencement of this preliminary discovery period, however, Symczyk had no opportunity to gather such evidence before the court granted defendants’ motion to dismiss. Had Symczyk been operating under the assumption that the court would employ the "substantial allegation” standard, she may have been prepared to move for “conditional certification” without conducting minimal discovery. And, had the court in fact facilitated notice to potential opt-ins based solely on the allegations in Symczyk's complaint, defendants’ Rule 68 offer may not have antedated the arrival of a consent form from a party plaintiff, an occurrence that would have fundamentally transformed the court’s mootness analysis.
. Because only the notice stage is implicated in this appeal, we need not directly address the level of proof required to satisfy the similarly situated requirement at the post-discovery stage. Although this standard must necessarily be more rigorous than the standard applicable at the notice stage, the fact-specific, flexible nature of this approach affords district judges latitude in exercising their discretion. See 45C Am.Jur.2d Job Discrimination § 2184 (2011) (listing fourteen factors courts may consider at the post-discovery stage). As we have explained:
A representative (but not exhaustive or mandatory) list of relevant factors [at this stage] includes whether the plaintiffs are employed in the same corporate department, division and location; advanced similar claims of ... discrimination; sought substantially the same form of relief; and had similar salaries and circumstances of employment. Plaintiffs may also be found dissimilar on the basis of case management issues, including individualized defenses.
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Ruehl v. Viacom, Inc.,
. In
Hoffmann-La Roche,
the Supreme Court recognized the efficacy of § 216(b) hinges on “employees receiving accurate and timely notice concerning the pendency of the collective action, so that they can make informed decisions about whether to participate.”
. In
Weiss,
we noted that our opinion might be viewed as creating tension with
Lusardi,
which involved alleged violations of the Age Discrimination in Employment Act (ADEA), 29 U.S.C. § 621
et seq.
Section 7(b) of the ADEA incorporates § 216(b) by reference.
See
29 U.S.C. § 626(b). However, in distinguishing
Lusardi,
we did not rely on the differences between the procedures applicable to Rule 23 and § 216(b) actions.
See Weiss,
In this appeal, the 'picking off scenarios described by the Supreme Court in Roper are directly implicated. In Lusardi they were not.... In Lusardi, no unilateral action by the Defendant rendered the plaintiffs’ claims 'inherently transitory.’ Defendants here used the Rule 68 offer to thwart the putative class action before the certification question could be decided.
Id. These considerations are not unique to the Rule 23 context, and Weiss did not turn on the disparity between opt-in and opt-out actions.
. Relying on a careful analysis of various district court efforts to grapple with the interplay of Rule 68 and § 216(b) provided in
Briggs v. Arthur T. Mott Real Estate LLC,
No. 06-0468,
. Of course, class actions certified under Rule 23(b)(1) or (b)(2) are “mandatory” class actions in that class members are not permitted to opt out.
Wal-Mart Stores, Inc. v. Dukes,
- U.S. -,
. As noted, the Portal-to-Portal Act notionally abolished “representative actions.”
See
Pub.L. No. 80-49, § 5(a), 61 Stat. 84, 87 (1947). This amendment, however, did not strip an employee — such as Symczyk — of her right to act on behalf of similarly situated coworkers. Rather, the 1947 amendment eliminated the so-called “agency suit,” divesting nonparty representatives of standing to initiate actions under § 216(b).
See id.
"By identifying employees’ as the only proper parties in a § 216(b) action, the Portal to Portal Act aimed to ban representative actions that previously had been brought by unions on behalf of employees.”
Cameron-Grant
v.
Maxim Healthcare Servs.,
.In both
Susman
and
Zeidman,
the relation back rationale was deployed to salvage a court’s jurisdiction over class complaints when the named plaintiffs' claims had ostensibly been mooted while their motions for class certification were pending. However, because “the federal rules do not require certification motions to be filed with the class complaint, nor do they require or encourage premature certification determinations,” we explained in
Weiss
that "reference to the bright line event of the filing of the class certification motion may not always be well-founded.”
. Plaintiffs seeking recovery under the FLSA must commence an action within two years of the alleged violation (or within three years if the violation is ‘‘willful'’). 29 U.S.C. § 255(a).
. Defendants contend a party plaintiff's cause of action vests at the moment he files his consent form and that no conception of the relation back doctrine would permit this statutorily mandated act of opting in to relate back to the filing of the collective action complaint. While perhaps true, this assertion is beside the point. For the sake of argument, consider a hypothetical co-worker of Symczyk's who was subjected to a willful FLSA violation and whose tenure with the company also ended in December 2007. Because Symczyk's complaint was dismissed before this (or any) employee had opted in to the action, this potential plaintiff forfeited any claim to relief in December 2010. The relation back doctrine cannot, at this juncture, redeem this would-be plaintiff’s cause of action. However, had Symczyk been permitted to move — in timely fashion — for "conditional certification” in light' of defendants' March 2010 motion to dismiss, this plaintiff may have received notice of the ongoing collective action prior to her claim growing stale.
