Full opinion text
BERZON, Circuit Judge: The present appeal arises from the decertification of a pair of related collective actions brought under the Fair Labor Standards Act ("FLSA"), 29 U.S.C. § 207. Between 2004 and 2009, roughly 2,500 officers ("the Officers") of the Los Angeles Police Department ("the Department") opted into two collective actions alleging a pervasive, unwritten policy discouraging the reporting of overtime. After notice to potential collective action members and several years of discovery, the government defendant, the City of Los Angeles ("the City"), moved for decertification of the collective actions on the ground that the Officers within each were not "similarly situated" within the meaning of section 16(b) of the FLSA, 29 U.S.C. § 216(b). According to the City, if any Officers were denied pay for their earned overtime, it was due to unrelated instances of worksite- and supervisor-specific misconduct, rather than a single, Department-wide policy or practice. The district court granted the City's motion for decertification and dismissed the Officers without prejudice to refiling their FLSA claims individually. The original plaintiffs in the two decertified actions then reached settlements with the City on their own claims, and the district court entered final judgment. Although no longer plaintiffs at that point, the Officers filed timely appeals from final judgment, challenging their decertification and dismissal. We are asked first whether the Officers can appeal a decertification order when they were dismissed from the collective action before final judgment and without prejudice to their individual FLSA claims. We hold that they can. Opt-in plaintiffs are parties to the collective action, and an order of decertification and dismissal disposes of their statutory right to proceed collectively. They therefore have standing to appeal and may do so after the interlocutory decertification order to which they are adverse merges with final judgment. We are asked next whether the collective actions here were properly decertified and the Officers properly dismissed for failure to satisfy the "similarly situated" requirement of the FLSA. We hold that they were. Although the district court erred in its interpretation of the "similarly situated" requirement and in the standard it applied in evaluating decertification, a de novo review of the record reflects that the Officers failed, as a matter of law, to create a triable question of fact regarding the existence of a Department-wide policy or practice. In the absence of such a policy or practice, and in the absence of allegations of any other similarity of law or fact material to the disposition of the Officers' claims, the Officers were not "similarly situated" within the meaning of the FLSA. I Because much of this case turns on terminology and procedures specific to the FLSA, we begin with a brief explanation of 29 U.S.C. § 216(b) and the collective action mechanism that arises from it. The relevant language of section 216(b) is spare: An action to recover the liability prescribed in [this subsection] may be maintained against any employer (including a public agency) in any Federal or State court of competent jurisdiction by any one or more employees for and in behalf of himself or themselves and other employees similarly situated. No employee shall be a party plaintiff to any such action unless he gives his consent in writing to become such a party and such consent is filed in the court in which such action is brought. ... The right provided by this subsection to bring an action by or on behalf of any employee, and the right of any employee to become a party plaintiff to any such action, shall terminate upon the filing of a complaint by the Secretary of Labor .... 29 U.S.C. § 216(b). It is evident from the statute that workers may litigate jointly if they (1) claim a violation of the FLSA, (2) are "similarly situated," and (3) affirmatively opt in to the joint litigation, in writing. Id. It is evident also that the "right" to litigate jointly has two permutations: The statute refers to "[t]he right ... to bring an action by or on behalf of any employee," and to "the right of any employee to become a party plaintiff to any such action," id. -that is, the right to bring the collective litigation and the right to join it. But the statute specifies little else. It does not prescribe terms for the resulting proceeding. It does not provide a definition of "similarly situated," on which access to the collective mechanism typically turns. It does not establish a process for evaluating the propriety of a collective proceeding as litigation unfolds-for example, it makes no mention of "certification" or "decertification" of a collective action. And it says nothing about the standard the district court should apply when the collective mechanism is challenged. Given these gaps, much of collective action practice is a product of interstitial judicial lawmaking or ad hoc district court discretion. In particular, although nothing in section 216(b) expressly compels it, it is now the near-universal practice to evaluate the propriety of the collective mechanism-in particular, plaintiffs' satisfaction of the "similarly situated" requirement-by way of a two-step "certification" process. See 1 McLaughlin on Class Actions § 2:16 (14th ed. 2017). As this process most often functions, plaintiffs will, at some point around the pleading stage, move for "preliminary certification" of the collective action, contending that they have at least facially satisfied the "similarly situated" requirement. See 1 McLaughlin on Class Actions § 2:16. Later, after the necessary discovery is complete, defendants will move for "decertification" of the collective action on the theory that the plaintiffs' status as "similarly situated" was not borne out by the fully developed record. Id. We will address in subsequent sections the propriety of this two-step approach, as well as the proper means of evaluating whether plaintiffs are entitled to litigate in a collective action. As an initial matter, however, it is useful to address certain common misconceptions about the "preliminary certification" and "decertification" of collective actions. As noted, neither "certification" nor "decertification" appears in text of section 216(b). The terms have instead been adopted from Federal Rule of Civil Procedure 23, which governs class actions in federal court. The underlying assumption of that appropriation seems to be that collective and class actions, which to a degree resemble one another, must be handled in procedurally parallel ways. That assumption is unfounded. Collective actions and class actions are creatures of distinct texts-collective actions of section 216(b), and class actions of Rule 23 -that impose distinct requirements. See 7B Fed. Prac. & Proc. Civ. § 1807 (citing examples of cases so observing). The "expedient adoption of Rule 23 terminology with no mooring in the statutory text of § 216(b)" risks "inject[ing] a measure of confusion into the wider body of FLSA jurisprudence"-and has likely already done so. Symczyk v. Genesis HealthCare Corp. , 656 F.3d 189, 194 (3d Cir. 2011), rev'd on other grounds , 569 U.S. 66, 133 S.Ct. 1523, 185 L.Ed.2d 636 (2013). "Preliminary certification" of an FLSA collective action-also known as "provisional" or "conditional" certification-is an example of the confusion sown by the Rule 23 analogy. The term "certification" calls to mind an affirmative decision by the district court, as in the Rule 23 context, to allow a collective action to go forward. See Fed. R. Civ. P. 23(c)(1)(A). Yet, unlike in the Rule 23 context, the district court in a collective action plays no such gatekeeping role. Preliminary certification in the FLSA context does not "produce a class with an independent legal status[ ] or join additional parties to the action." Genesis Healthcare Corp. v. Symczyk , 569 U.S. 66, 75, 133 S.Ct. 1523, 185 L.Ed.2d 636 (2013). "The sole consequence" of a successful motion for preliminary certification is "the sending of court-approved written notice" to workers who may wish to join the litigation as individuals. Id. Given its purpose, preliminary certification may take place after the collective action has already begun. A collective action is instituted when workers join a collective action complaint by filing opt-in forms with the district court. See id. ; Rangel v. PLS Check Cashers of Cal. , 899 F.3d 1106, 1109 n.1 (9th Cir. 2018) ; Smith v. T-Mobile USA Inc. , 570 F.3d 1119, 1122-23 (9th Cir. 2009) ; Sandoz , 553 F.3d at 919 ; Morgan , 551 F.3d at 1259. Whether opt-in forms are filed after or before preliminary certification is thus entirely up to the workers joining the litigation; preliminary certification is "neither necessary nor sufficient for the existence of a [collective] action." Myers v. Hertz Corp. , 624 F.3d 537, 555 n.10 (2d Cir. 2010) (emphasis added). "Decertification" is another appropriation-and another misappropriation-from the Rule 23 context. Again, the term implies that a district court has some threshold role in creating a collective action. But, once more, section 216(b) does not provide for any "certification" process in the ordinary sense. Under section 216(b), workers have a "right" to bring or join a collective action, and may create the collective action of their own accord by filing opt-in forms. See 29 U.S.C. § 216(b) ; Symczyk , 569 U.S. at 75, 133 S.Ct. 1523. For a collective action to be "decertified," then, means that the plaintiffs cannot proceed collectively on the existing complaint because they are not similarly situated, so the opt-in plaintiffs must be dismissed. Despite the imprecision, we will adhere to the terms commonly used in collective action practice, as the terms are now widespread. For the reasons we have explained, we do not mean by the use of terms derived for the class action context to imply that there should be any particular procedural parallels between collective and class actions. See Symczyk , 656 F.3d at 194. We turn now to the facts and procedural history of this case. II Since at least 2000, the Officers have been subject to a written, FLSA-compliant policy prohibiting off-the-clock work. According to this policy, the Officers are required to report all overtime accurately, in six-minute increments, whether or not the overtime was approved in advance by a supervisor. The written policy states that those who fail to comply may be subject to discipline. This overtime policy was widely known among the Officers. Since at least 2000, the overtime policy has been memorialized in the Officers' collective-bargaining agreements, in letters to the Officers from the Los Angeles Chief of Police, and in the Department manual. No Officer claims ignorance of the official obligation to report overtime accurately. The Officers contend, however, that the Department follows an unwritten policy that dissuades, and as a practical matter prevents, accurate time reporting. According to the Officers, supervisors routinely require short blocks of extra work-pre-shift work, post-shift work, or work through meal breaks-yet discourage or reject overtime claims in amounts of less than one hour. The Officers' allegations of an unwritten, Department-wide policy served two purposes. First, it went to the merits of the Officers' FLSA claims. The FLSA requires covered workers to be paid at least 1.5 times their normal rate for all work in excess of forty hours weekly, 29 U.S.C. § 207(a)(1), provided the employer has actual or constructive knowledge that the work is occurring. 29 C.F.R. § 785.11 ; Forrester v. Roth's I.G.A. Foodliner, Inc. , 646 F.2d 413, 414 (9th Cir. 1981). Employers who violate this requirement are liable for damages in the amount of the unpaid overtime, "an additional equal amount as liquidated damages," and "reasonable attorney's fee ... and costs." 29 U.S.C. § 216(b). An unwritten policy discouraging the reporting of overtime, if proven at trial, would both lend credence to the Officers' claims that they incurred unpaid overtime and help satisfy the element of knowledge. Second, credible allegations of a Department-wide policy should suffice to make the Officers similarly situated, as required to maintain a collective action. See id. The first of the two collective actions at issue in this appeal, Alaniz v. City of Los Angeles , No. CV 04-8592 AG (AJWx), was filed in 2004. By the end of 2007, the Alaniz collective action had been joined by over 2,200 Officers. The second of the collective actions, Mata v. City of Los Angeles , No. CV 07-06782 AG (AJWx), was filed in 2007. By the end of 2009, it had been joined by over 150 Officers. The parties in Alaniz stipulated to preliminary certification of the collective action in mid-2006. The parties in Mata did not so stipulate. But the two cases were related by the district court shortly after Mata was filed, and thereafter proceeded on the same track, with overlapping discovery. Discovery was extensive, lasted several years, and was complete for the purposes of decertification at the time the City filed its decertification motion. The City moved for decertification of both collective actions in January 2014. In opposition, the Officers submitted 232 declarations, each from a different Officer claiming uncompensated overtime. These declarations were largely identical, except for each declarant's identifying information and his or her estimate of the average time spent each day in unscheduled pre-shift, post-shift, and meal-break work. A small number of declarations referred to specific instances of supervisors discouraging or rejecting overtime reports for small increments of time. The Officers also submitted 50 declarations, each from a different Officer, listing types of uncompensated tasks and stating, generally, that workplace "culture and policy" discouraged accurate time reporting. These declarations-also largely identical, except for each declarant's list of tasks-stated that supervisors were aware of off-the-clock work and knew that the Department benefitted from it, but did not insist that the Officers report it. The declarations also stated that the declarants learned from their first days with the Department that, notwithstanding written rules to the contrary, overtime in amounts of less than one hour was not to be reported. In support of its motion for decertification, the City submitted an analysis of the overtime that was reported. This analysis, uncontroverted by the Officers, revealed roughly 6.6 million overtime reports between 2001 and 2014. Of these 6.6 million reports, 330,000 reports were for overtime of less than one hour, and 112,000 were for overtime of less than 30 minutes. Of the reports claiming less than an hour of overtime, 64,000 were filed by plaintiffs in the Alaniz and Mata actions. The City also submitted uncontroverted evidence demonstrating the Officers' dissimilarity in tasks and in geographic assignments. According to the declaration submitted by the Department's FLSA compliance manager, the Officers worked at seven different ranks and within each of the Department's 31 divisions. The Officers had at least hundreds of different supervisors among them. To determine whether, in light of this evidence, the Officers were "similarly situated" within the meaning of the FLSA, the district court applied a three-prong test widely used in district courts both within this circuit and without, although it has not been endorsed by this court: First, the district court considered the "factual and employment setting" of the Officers. According to the district court, the "boilerplate" nature of the Officers' declarations called into question their evidentiary value, whereas the City's uncontroverted evidence reflected widespread compliance with the overtime reporting policy, even for fairly short periods of overtime. As a result, the officers could not have been subject to a uniform policy preventing the reporting of overtime period of less than one hour. In the absence of such a policy, the district court concluded, the Officers' claims were necessarily tied to discrete worksites and supervisors, and unsuited to a collective of the scale the Officers sought. Second, the district court considered the defenses available to the City. The district court found many of these defenses-lack of actual or constructive knowledge, good faith, the de minimis nature of the alleged overtime violations-situation-specific, and thus difficult to address on a collective basis. Finally, the district court considered "fairness and procedural considerations," and concluded that there was no benefit to the court or to the parties in attempting to litigate collectively. As all three factors weighed in favor of decertification, the district court granted the City's motion and dismissed the Officers without prejudice. Shortly thereafter, the original plaintiffs, who had been left behind after decertification, settled their individual FLSA claims with the City. The district court entered judgment, and the present appeals followed. III Whether opt-in plaintiffs can appeal a decertification order is a question of first impression in this circuit. The City raises several objections to appellate jurisdiction and to the Officers' standing to appeal-that the opt-in plaintiffs are not "parties," that the decertification was interlocutory, and that the dismissal was without prejudice. None has merit. A The FLSA leaves no doubt that "every plaintiff who opts in to a collective action has party status." Halle v. W. Penn Allegheny Health Sys. Inc. , 842 F.3d 215, 225 (3d Cir. 2016) (quoting Wright & Miller, 7B Fed. Prac. & Proc. Civ. § 1807 (3d ed. 2018) ). Under the FLSA, an opt-in plaintiff's action is deemed "commenced" from the date her opt-in form is filed with the district court. 29 U.S.C. § 256. From that point on, there is no statutory distinction between the roles or nomenclature assigned to the original and opt-in plaintiffs. See Mickles v. Country Club Inc. , 887 F.3d 1270, 1278 (11th Cir. 2018). The FLSA does not use the terms "original" or "opt-in" plaintiff at all; the FLSA instead refers to all plaintiffs in a collective action as "party plaintiff[s]." 29 U.S.C. § 256(a). Where necessary to distinguish between the party plaintiffs who brought the suit and those who joined after its filing, the FLSA speaks only of the party plaintiffs "specifically named ... in the complaint" and those "not so" named. 29 U.S.C. § 256(a) - (b). The natural parallel is to plaintiffs initially named or later added under the ordinary rules of party joinder. See Fed. R. Civ. P. 20(a)(1). The contrast with class action practice is instructive. Rule 23 allows for representative actions in which class members' interests are litigated by the named plaintiff. In part because of the due process concerns inherent such a proceeding, the district court must initially approve the creation of a class and the appointment of an adequate representative. See Phillips Petroleum Co. v. Shutts , 472 U.S. 797, 811-12, 105 S.Ct. 2965, 86 L.Ed.2d 628 (1985) ; Hanlon v. Chrysler Corp. , 150 F.3d 1011, 1024 (9th Cir. 1998) ; Blackie v. Barrack , 524 F.2d 891, 910 (9th Cir. 1975). Proceeding as a class action is thus conditioned on the court's approval and results in a less active role in the litigation for members of the class than if litigating individually. A collective action, on the other hand, is not a comparable form of representative action. Just the opposite: Congress added the FLSA's opt-in requirement with the express purpose of "bann[ing]" such actions under the FLSA. Portal-to-Portal Act of 1947, Pub. L. No. 80-49, § 5(a), 61 Stat. 84, 87; Hoffmann-La Roche Inc. v. Sperling , 493 U.S. 165, 173, 110 S.Ct. 482, 107 L.Ed.2d 480 (1989). A collective action is more accurately described as a kind of mass action, in which aggrieved workers act as a collective of individual plaintiffs with individual cases-capitalizing on efficiencies of scale, but without necessarily permitting a specific, named representative to control the litigation, except as the workers may separately so agree. See Abraham v. St. Croix Renaissance Grp., L.L.L.P. , 719 F.3d 270, 272 n.1 (3d Cir. 2013). The opt-in plaintiffs thus choose whether and when to "become parties to a collective action only by filing a written consent with the court." Symczyk , 569 U.S. at 75, 133 S.Ct. 1523 ; see also Kinney Shoe Corp. v. Vorhes , 564 F.2d 859, 862 (9th Cir. 1977), abrogated on other grounds by Hoffmann-La Roche , 493 U.S. 165, 110 S.Ct. 482, 107 L.Ed.2d 480. And the result of joining the collective is "the same status in relation to the claims of the lawsuit as [that held by] the [original] named plaintiffs." Prickett v. DeKalb County , 349 F.3d 1294, 1297 (11th Cir. 2003) (per curiam). Given this structure, the dismissal of the opt-in plaintiffs before the entry of final judgment-"decertification"-has no impact on their party status for purposes of appeal. Party status does not depend on being present in the district court litigation from the moment it began or at the moment it ended. All "those that properly become parties[ ] may appeal an adverse judgment." Marino v. Ortiz , 484 U.S. 301, 304, 108 S.Ct. 586, 98 L.Ed.2d 629 (1988) ; Mickles , 887 F.3d at 1278. Nor, contrary to the City's position, did their dismissal as opt-in plaintiffs before the entry of judgment prevent the Officers in this case from being "bound" by the judgment and thus eligible to challenge it on appeal. A decertification order disposes only of the right to proceed collectively as the collective was defined in the complaint; it leaves the original plaintiff to continue litigating. Such an order is therefore interlocutory, see Ray Haluch Gravel Co. v. Cent. Pension Fund of Int'l Union of Operating Eng'rs & Participating Emp'rs , 571 U.S. 177, 183, 134 S.Ct. 773, 187 L.Ed.2d 669 (2014), and, like interlocutory orders generally, merges with final judgment. Hook v. Ariz. Dep't of Corr. , 107 F.3d 1397, 1401 (9th Cir. 1997) ; see also Mickles , 887 F.3d at 1278-79. The City argues that opt-in plaintiffs, even if competent to appeal from a final judgment generally, cannot appeal an order dismissing them without prejudice. It is unclear whether the City intends this argument as a challenge to the finality of the order appealed from as a basis for this court's appellate jurisdiction, or to the Officers' appellate standing. In either case, the City is mistaken. As to appellate jurisdiction, the City confuses finality, which is a condition of appealability under 28 U.S.C. § 1291, with an adverse disposition on the merits, which is not. "That [a] dismissal is without prejudice and the litigation may be renewed [in a new action] does not affect ... appealability ...." Thompson v. Potashnick Constr. Co. , 812 F.2d 574, 576 (9th Cir. 1987). The touchstone for finality is that the particular action filed is fully disposed of, without the possibility of being resurrected through amendment. See, e.g. , Griffin v. Arpaio , 557 F.3d 1117, 1119 (9th Cir. 2009) ; Montes v. United States , 37 F.3d 1347, 1350 (9th Cir. 1994). Applying these standards, whether a dismissed party to the action could litigate the same merits issue by filing a different case does not matter. The judgment entered here plainly qualifies as final and so appealable. As to appellate standing, the Officers were, as noted, parties to the action at the time they opted in, and parties to the action at the time they were dismissed. Although the dismissal was without prejudice to the merits of the Officers' individual FLSA claims, it removed them from the action they chose to join and disposed of their statutory right to proceed in a collective as that collective was defined in the complaint. See 29 U.S.C. § 216(b). The City, citing McElmurry v. U.S. Bank National Ass'n , 495 F.3d 1136, 1138-39 (9th Cir. 2007), contends no such right exists, but it does not attempt to square this assertion with the plain language of the FLSA, which twice uses the term "right." We did not hold in McElmurry that the FLSA provides no "right" to a collective action. We held only that the risk of losing that right because of a limitations problem did not justify applying the collateral-order doctrine to ensure immediate review of a denial of preliminary certification. Id. at 1139-41. In short, the dismissal of the Officers removed them from the litigation, an ouster they maintain violated their right under the FLSA to pursue their claims collectively. The dismissal order then merged into the final judgment. Nothing more is needed for appellate jurisdiction or for standing. See, e.g. , Ramirez v. Fox Television, Inc. , 998 F.2d 743, 747 (9th Cir. 1993) (noting that any "order which effectively sends a party out of court is appealable" (quoting United States v. Lee , 786 F.2d 951, 956 (9th Cir. 1986) ) ); Norwest Bank Minn., N.A. v. Sween Corp. , 118 F.3d 1255, 1257 n.1 (8th Cir. 1997) (noting that a party dismissed before a ruling on the merits may appeal the dismissal to which it was a party, but not the merits ruling to which it was not). B We recognize that the Third Circuit recently confronted similar issues in Halle v. West Penn Allegheny Health System , 842 F.3d 215 (3d Cir. 2016), and reached a somewhat different conclusion. In Halle , an opt-in plaintiff, after being dismissed from a collective action, refiled his FLSA claims as the original plaintiff of a new collective action. Id. at 221-22. Other opt-in plaintiffs dismissed from the first iteration of the case then promptly joined, and the defendant moved for decertification. Id. The district court granted the decertification motion on preclusion grounds, treating the decertification order from the first case as collaterally estopping a collective action in the second. Id. at 222. The original plaintiff in the second suit then settled, and a group of opt-in plaintiffs-now twice-dismissed-appealed. Id. The Third Circuit concluded, as have we, that "[a]ppellate review of th[e] interlocutory decertification decision [was] available by proceeding to a final judgment on the merits of [the original plaintiff's] individual claims." Id. at 228. The Third Circuit then determined, however, that only the original plaintiff had the authority to seek appellate review. According to the Third Circuit, dismissal of the opt-in plaintiffs deprived them of party status, and thus deprived them of the ability to appeal their dismissal after final judgment. Id. at 229. In so holding, the Third Circuit contrasted the opt-in plaintiffs' position with that of Rule 23 class members appealing from approval of a class settlement. Id. Whereas class members who do not opt out are parties to the settlement and bound by it, opt-in plaintiffs dismissed from an FLSA collective action are not parties to the original plaintiff's post-decertification settlement of her individual claims. Id. According to the Third Circuit, the opt-in plaintiffs were therefore "not subject to a final decision disposing of their rights from which they may file an appeal under § 1291." Id. We disagree. The Third Circuit's approach rests on a flawed understanding of the scope of a final judgment. A final judgment is not limited to orders disposing of claims on their merits, nor is it limited to orders affecting the plaintiffs originally named in the complaint or still remaining at the time the case is fully resolved. Opt-in plaintiffs become parties to an FLSA action upon opting into it. 29 U.S.C. § 216(b). They are therefore parties to the order decertifying the collective action and dismissing them from the suit-which is of course the only reason the district court in Halle was able to dismiss the opt-in plaintiffs from the second collective action on issue-preclusion grounds. As Halle acknowledged, a decertification order is interlocutory. Halle , 842 F.3d at 226-27. It therefore merges with final judgment, such that the parties affected by it may appeal at that time. See id. at 228. In the context of a voluntary dismissal-the path to settlement in the present cases-appeal is permitted from "a voluntary dismissal which imposes a condition that creates sufficient prejudice in a legal sense." Coursen v. A.H. Robins Co. , 764 F.2d 1329, 1342 (9th Cir. 1985) ), opinion corrected , 773 F.2d 1049 ; see also Concha v. London , 62 F.3d 1493, 1507 (9th Cir. 1995). Where the original plaintiff's voluntary dismissal results in a final judgment disposing of other, non-settling plaintiffs' statutory right to proceed collectively, that standard is met. See also Espenscheid v. DirectSat USA, LLC , 688 F.3d 872, 877-78 (7th Cir. 2012) (concluding that the original plaintiff in a collective action may appeal a decertification order after voluntarily dismissing his FLSA claims). So, although choosing to settle claims may prevent the settling plaintiff from appealing, for the non-settling plaintiffs, it is immaterial that the settling plaintiff cannot be a party to the appeal. Particularly if, as the Third Circuit assumed, the decertification order is issue-preclusive as to the availability of a collective action against all plaintiffs dismissed as a result of it, it cannot be that only the original plaintiff is competent to appeal. We are not the first circuit to reject the appealability reasoning in Halle . Although it did not describe itself as creating a split in authority, the Eleventh Circuit in Mickles concluded that opt-in plaintiffs could appeal a denial of preliminary certification after the entry of final judgment. Mickles , 887 F.3d at 1278-79. It so concluded because, even though the opt-in plaintiffs were "not bound by the final order approving settlement" between the original plaintiff and the employer, they were bound by the final judgment into which earlier interlocutory orders merged. Id. at 1279. Mickles dealt with a different interlocutory order than we do-a denial of preliminary certification, rather than a grant of decertification-but its reasoning tracks our own, and is equally inconsistent with that in Halle . C The City argues, in the alternative, that the terms of the Officers' opt-in forms prevent them from appealing, because the forms entrusted all "certification" questions to the original plaintiff. Again, the City relies heavily on Halle , which adopted the City's view based on the opt-in language at issue in that case. First, nothing inherent in the opt-in process requires waiving the right or delegating the responsibility to appeal a decertification order. The spare language of the FLSA regarding the opt-in form refers only to a "consent in writing to become ... a party." 29 U.S.C. § 216(b). Accordingly, if the members of a collective reach their own agreement to delegate litigation duties, such an agreement marks a deviation from the statute's default assumption of coequal status. Second, nothing about the opt-in forms in this case-which differ substantially from those in Halle -suggests that the Officers delegated their authority to appeal an order ousting them from the case. The consent forms here at issue state only, "I ... authorize the filing and prosecution of the action in my name." The district court's decertification order in essence negated that consent, by dismissing the opt-in plaintiffs from the suit; no longer could the action be prosecuted in their names. So, to the extent there was a delegation here, it was not a delegation that survived the decertification. IV As there is no obstacle to appellate review in this case, we turn to the district court's decertification order. The Officers challenge the order both on its interpretation of the FLSA and on its application of the FLSA to the record. A Beginning with the district court's interpretation of the FLSA, we note that neither the FLSA nor the case law of this circuit offers much express guidance on collective action practice. As previously discussed, it is clear from the language of section 216(b) that (1) workers may join a collective action if they claim a violation of the FLSA, are "similarly situated" to the original plaintiff, and affirmatively opt in; and (2) participation in the collective action is a statutory "right" held equally and individually by each party plaintiff, whether originally appearing in the complaint or later opting in. 29 U.S.C. § 216(b). However, the FLSA leaves the collective action procedures-beyond the requirement of a written opt-in-open. As here relevant, the FLSA does not establish a process for evaluating the propriety of the collective mechanism as litigation proceeds. It does not provide a definition of "similarly situated"-the requirement that largely determines the viability of a collective action. And it says nothing about the standard the district court should apply when the collective mechanism is challenged. We address each question in turn. 1 In the absence of statutory or case law guidance, the district courts, both within this circuit and without, have arrived at a loose consensus as to the proper procedure for determining whether the collective mechanism is appropriate. See 1 McLaughlin on Class Actions § 2:16 (14th ed. 2017) ; see also Leuthold , 224 F.R.D. at 466-67 (citing examples). First, at or around the pleading stage, plaintiffs will typically move for preliminary certification. 1 McLaughlin on Class Actions § 2:16 ; 7B Fed. Prac. & Proc. Civ. § 1807. Preliminary certification, as noted, refers to the dissemination of notice to putative collective members, conditioned on a preliminary determination that the collective as defined in the complaint satisfies the "similarly situated" requirement of section 216(b). Symczyk , 569 U.S. at 75, 133 S.Ct. 1523. At this early stage of the litigation, the district court's analysis is typically focused on a review of the pleadings but may sometimes be supplemented by declarations or limited other evidence. See, e.g. , Sheffield v. Orius Corp. , 211 F.R.D. 411, 413 (D. Or. 2002). The level of consideration is "lenient," Camesi v. Univ. of Pittsburgh Med. Ctr. , 729 F.3d 239, 243 (3d Cir. 2013) ; Anderson v. Cagle's, Inc. , 488 F.3d 945, 953 (11th Cir. 2007) -sometimes articulated as requiring "substantial allegations," sometimes as turning on a "reasonable basis," but in any event loosely akin to a plausibility standard, commensurate with the stage of the proceedings. See, e.g. , Halle , 842 F.3d at 224 ; Morgan , 551 F.3d at 1260 n.38 ; Thiessen , 267 F.3d at 1105 ; Mooney v. Aramco Servs. Co. , 54 F.3d 1207, 1214 (5th Cir. 1995), overruled on other grounds by Desert Palace, Inc. v. Costa , 539 U.S. 90, 123 S.Ct. 2148, 156 L.Ed.2d 84 (2003) ; cf. Fed. R. Civ. P. 12(b)(6) ; Ashcroft v. Iqbal , 556 U.S. 662, 679, 129 S.Ct. 1937, 173 L.Ed.2d 868 (2009). A grant of preliminary certification results in the dissemination of a court-approved notice to the putative collective action members, advising them that they must affirmatively opt in to participate in the litigation. 1 McLaughlin on Class Actions § 2:16 ; 7B Fed. Prac. & Proc. Civ. § 1807 ; see also Hoffmann-La Roche , 493 U.S. at 170-71, 110 S.Ct. 482. A denial of preliminary certification precludes dissemination of any such notice. Denial of preliminary certification may be without prejudice and may be revisited by the district court after further discovery. Halle , 842 F.3d at 225 ; see, e.g. , D'Anna v. M/A-COM, Inc. , 903 F.Supp. 889, 894 (D. Md. 1995). Or it may be with prejudice, in which case, if premised on the party plaintiffs' failure to satisfy the "similarly situated" requirement of section 216(b), it functions as an unfavorable adjudication of the right to proceed in a collective. Mickles , 887 F.3d at 1280 ; see also Sandoz , 553 F.3d at 915 n.2. In such cases, if opt-in plaintiffs have already joined, they will be dismissed without prejudice to the merits of their individual FLSA claims, and the original plaintiff will be left to litigate alone. Mickles , 887 F.3d at 1280 (citing examples). Assuming the collective action has survived its earlier scrutiny, the second stage will come at or after the close of relevant discovery. See Hipp v. Liberty Nat'l Life Ins. Co. , 252 F.3d 1208, 1218 (11th Cir. 2001) (per curiam). The employer can move for "decertification" of the collective action for failure to satisfy the "similarly situated" requirement in light of the evidence produced to that point. 1 McLaughlin on Class Actions § 2:16 ; 7B Fed. Prac. & Proc. Civ. § 1807. The district court will then take a more exacting look at the plaintiffs' allegations and the record. Anderson , 488 F.3d at 953 ; Thiessen , 267 F.3d at 1102-03. Because of its purpose and timing, decertification can resemble a motion for partial summary judgment on the "similarly situated" question, and may be combined with cross-motions for summary judgment. See, e.g. , Sargent v. HG Staffing, LLC , 171 F.Supp.3d 1063, 1070 (D. Nev. 2016). If the motion for decertification is granted, the result is a negative adjudication of the party plaintiffs' right to proceed in a collective as that collective was defined in the complaint. The opt-in plaintiffs are dismissed without prejudice to the merits of their individual claims, and the original plaintiff is left to proceed alone. Hipp , 252 F.3d at 1218. If the motion for decertification is denied, the collective proceeds toward trial, at least on the questions justifying collective treatment. Id. In determining, as a matter of first impression in this circuit, how to evaluate a motion for decertification, we first must confirm that the district court was correct in considering decertification at the point it did, and on the record then available. We conclude that it was. The two-step approach has been endorsed by every circuit that has considered it. See Myers , 624 F.3d at 554-55 (2d Cir.) ; Camesi , 729 F.3d at 243 (3d Cir.) ; White , 699 F.3d at 877 (6th Cir.) ; Thiessen , 267 F.3d at 1105 (10th Cir.) ; Morgan , 551 F.3d at 1260 (11th Cir.). There is good reason for this consensus. In the absence of any statutory directive, the proper means of managing a collective action-the form and timing of notice, the timing of motions, the extent of discovery before decertification is addressed-is largely a question of "case management," Hoffmann-La Roche , 493 U.S. at 174, 110 S.Ct. 482, and thus a subject of substantial judicial discretion. See GCB Commc'ns, Inc. v. U.S. S. Commc'ns, Inc. , 650 F.3d 1257, 1262 (9th Cir. 2011) ; see also, e.g. , Myers , 624 F.3d at 555 n.10 ; Comer v. Wal-Mart Stores, Inc. , 454 F.3d 544, 546 (6th Cir. 2006). There are of course limits to that discretion. In some cases, it may be that a district court abuses its discretion in refusing to allow notice to putative collective action members, or in decertifying too early or too late. See, e.g. , Woods v. N.Y. Life Ins. Co. , 686 F.2d 578, 580 (7th Cir. 1982) (observing that, in a valid collection action, "forbid[ding] the sending of notice altogether" would be an abuse of discretion). But as a general rule, the two-step process, culminating in a decertification motion on or after the close of relevant discovery, has the advantage of ensuring early notice of plausible collective actions, then eliminating those whose promise is not borne out by the record. The present case fits this mold well. Notice was provided to putative collective action members upon preliminary certification. Discovery was extensive, and the relevant record was complete at the time of the district court's ruling on the decertification motion. The district court did not abuse its discretion in considering the validity of the collective mechanism as it did, by way of the City's post-discovery motion for decertification. 2 We turn next to the meaning of the statutory term "similarly situated." As the question is one of statutory construction, we proceed de novo. In re Mitchell , 977 F.2d 1318, 1320 (9th Cir. 1992). There is no established definition of the FLSA's "similarly situated" requirement, nor is there an established test for enforcing it. See Thiessen , 267 F.3d at 1102. This absence of authority is surprising, as being "similarly situated" is the key condition for proceeding in a collective, and thus the issue on which a grant or denial of decertification generally depends. Nonetheless, broadly speaking, two approaches to the "similarly situated" requirement have emerged. See Mooney , 54 F.3d at 1214. a. The minority approach The minority approach is to treat a collective as an opt-in analogue to a Rule 23(b)(3) class. See Mooney , 54 F.3d at 1214 ; see also, e.g. , Shushan v. Univ. of Colo. at Boulder , 132 F.R.D. 263, 265 (D. Colo. 1990). District courts following the minority approach tend to expect a collective to satisfy the requirements of numerosity, commonality, typicality, adequacy, predominance, and superiority. Fed. R. Civ. P. 23(b)(3) ; see Thiessen , 267 F.3d at 1103. No circuit court has adopted the minority approach in toto. See 7B Fed. Prac. & Proc. Civ. § 1807 (collecting examples). The Seventh Circuit has imported the "predominance" requirement of Rule 23(b)(3) into section 216(b). Alvarez v. City of Chicago , 605 F.3d 445, 449 (7th Cir. 2010). It is unclear whether it would similarly import the other requirements of Rule 23. In Espenscheid v. DirectSat USA, LLC , 705 F.3d 770 (7th Cir. 2013), the Seventh Circuit did suggest that the section 216(b) and Rule 23 standards are already "largely merged ..., though with some terminological differences." Id. at 772. But Espenscheid 's depiction of section 216(b) reflects the Seventh Circuit's desire for "[s]implification" more than the text of the FLSA. Id. All other circuits to have considered the issue-including the Tenth Circuit, which Espenscheid inaccurately cites as supportive, see Thiessen , 267 F.3d at 1105 -have rejected the analogy to Rule 23. See, e.g. , Monroe v. FTS USA, LLC , 860 F.3d 389, 405-06 (6th Cir. 2017), cert. denied , --- U.S. ----, 138 S.Ct. 980, 200 L.Ed.2d 248 (2018) ; Grayson v. K Mart Corp. , 79 F.3d 1086, 1096 (11th Cir. 1996). We agree with the consensus view that the minority approach rests improperly on an analogy to Rule 23 lacking in support in either the FLSA or the Federal Rules of Civil Procedure. First, in language and structure, section 216(b) and Rule 23 bear little resemblance to one another. The limited statutory requirements of a collective action are "independent of, and unrelated to, the requirements for class action under Rule 23," Grayson , 79 F.3d at 1096 n.12, and, by omitting most of the requirements in Rule 23 for class certification, necessarily impose a lesser burden, see Calderone , 838 F.3d at 1104. See also LaChapelle v. Owens-Ill., Inc. , 513 F.2d 286, 289 (5th Cir. 1975). For example, section 216(b) does not mention predominance or superiority. Monroe , 860 F.3d at 397. And as nonrepresentative actions, collective actions have no place for conditions such as adequacy or typicality. This gap between the requirements of collective and class proceedings is to be expected, as many of the rules specific to class actions have evolved to protect the due process rights of absent class members, a consideration not pertinent under the post-1947 FLSA. See Portal-to-Portal Act, § 5(a); McElmurry , 495 F.3d at 1139 ; Espenscheid , 705 F.3d at 772. Second, as other circuits have noted, the FLSA not only imposes a lower bar than Rule 23, it imposes a bar lower in some sense even than Rules 20 and 42, which set forth the relatively loose requirements for permissive joinder and consolidation at trial. Fed. R. Civ. P. 20(a) ; Fed. R. Civ. P. 42 ; O'Brien , 575 F.3d at 584-85 ; Grayson , 79 F.3d at 1096 ; Lusardi , 855 F.2d at 1078. Whereas Rules 20 and 42 allow district courts discretion in granting joinder or consolidation, In re EMC Corp. , 677 F.3d 1351, 1360 (Fed. Cir. 2012), the FLSA, which declares a right to proceed collectively on satisfaction of certain conditions, does not. See 29 U.S.C. § 216(b) ; Grayson , 79 F.3d at 1096-97. Furthermore, Rule 20 requires, in addition to a common question of law or fact, that the plaintiffs assert a right to relief arising from "the same transaction[ ] [or] occurrence," Fed. R. Civ. P. 20(a)(1)(A), a condition with no parallel in the FLSA. See Hipp , 252 F.3d at 1219. Third, unlike Rule 23, the collective action mechanism is, in effect, tailored specifically to vindicating federal labor rights. The FLSA is a remedial statute with broad worker-protective aims. See Hoffmann-La Roche , 493 U.S. at 173, 110 S.Ct. 482 ; Anderson v. Mt. Clemens Pottery Co. , 328 U.S. 680, 687, 66 S.Ct. 1187, 90 L.Ed. 1515 (1946) ; Monroe , 860 F.3d at 396, 402-03, 405-06. The collective action mechanism is a means of serving these aims. See Hoffmann-La Roche , 493 U.S. at 173, 110 S.Ct. 482 ; Monroe , 860 F.3d at 396-97 ; O'Brien , 575 F.3d at 586. Rule 23, by contrast, is neither a creation of statute nor a provision of specific applicability to certain substantive rights or remedial schemes. Lastly, as section 216(b) makes no mention of "class" proceedings, one can surmise that the distinction between collective and class proceedings reflects an affirmative congressional choice "not to have the Rule 23 standards apply to [collective] actions." Thiessen , 267 F.3d at 1105. That choice was made clear upon introduction of the opt-in provision in 1947, which Congress accomplished without importing class-action requirements or terminology into the FLSA. See Calderone , 838 F.3d at 1105 ; O'Brien , 575 F.3d at 584. And it was recognized and reinforced by the Advisory Committee on Rules in 1966, when Rule 23 was amended with the caveat that "present provisions of 29 U.S.C. § 216(b) are not intended to be affected." Fed. R. Civ. P. 23 advisory committee notes to 1966 amendment; see also Calderone , 838 F.3d at 1106 ; Knepper v. Rite Aid Corp. , 675 F.3d 249, 257 (3d Cir. 2012). For all these reasons, mimicking the Rule 23 standards in evaluating section 216(b) collective actions is not appropriate. b. The majority approach The majority approach to the "similarly situated" requirement-the approach followed by the district court in this case, and by far the more common option -is a flexible inquiry into the factual differences between the party plaintiffs and the desirability of collective treatment. See Morgan , 551 F.3d at 1260 n.38. Under this approach, often called-not very helpfully-the "ad hoc" test, the district court applies a three-prong test that focuses on points of potential factual or legal dissimilarity between party plaintiffs. First, the district court considers the "disparate factual and employment settings of the individual plaintiffs." Thiessen , 267 F.3d at 1103. Second, the district court considers "the various defenses available to defendants which appear to be individual to each plaintiff." Id. Third, the district court considers "fairness and procedural considerations." Id. The ad hoc test is the only one that has been fully endorsed at the circuit level. See Morgan , 551 F.3d at 1260 n.38 (collecting examples). And that test is a significant improvement over the Rule 23 analogy. In omitting conditions with no grounding in the FLSA, the ad hoc test better accommodates the party plaintiffs' broad right to proceed collectively. O'Brien , 575 F.3d at 585. But the ad hoc test has two major flaws. First, although the ad hoc test is properly aimed at gauging whether party plaintiffs are legally or factually "similarly situated," it does so at such a high level of abstraction that it risks losing sight of the statute underlying it. As it stands, the ad hoc test offers no clue as to what kinds of "similarity" matter under the FLSA. It is, in effect, a balancing test with no fulcrum. The Third Circuit, for example, has offered a list of potentially salient considerations in ADEA cases-"whether the plaintiffs are employed in the same corporate department, division and location; [whether they] advanced similar claims of age discrimination ... [;] [whether they] had similar salaries and circumstances of employment"-but notes that none is necessarily dispositive in a given case, or even necessary to consider in every instance. See Ruehl v. Viacom, Inc. , 500 F.3d 375, 388 n.17 (3d Cir. 2007). The key question, then, is one the ad hoc test does not answer: what it means to be "similarly situated" specifically for the purposes of section 216(b). The abstractness of the ad hoc standard reflects the circuits' focus on providing "tests" for applying the "similarly situated" standard rather than beginning with the term's meaning. See Mooney , 54 F.3d at 1213. In doing so, the ad hoc approach tends to "explain[ ] what the term ['similarly situated'] does not mean-not what it does." Morgan , 551 F.3d at 1260 & n.38 ; see also Mooney , 54 F.3d at 1213. The natural answer to the proper inquiry-what "similarly situated" means-is, in light of the collective action's reason for being within the FLSA, that party plaintiffs must be alike with regard to some material aspect of their litigation. That is, the FLSA requires similarity of the kind that "allows ... plaintiffs the advantage of lower individual costs to vindicate rights by the pooling of resources." Hoffmann-La Roche , 493 U.S. at 170, 110 S.Ct. 482 ; see also Halle , 842 F.3d at 223-24. That goal is only achieved-and, therefore, a collective can only be maintained-to the extent party plaintiffs are alike in ways that matter to the disposition of their FLSA claims. See Halle , 842 F.3d at 226. If the party plaintiffs' factual or legal similarities are material to the resolution of their case, dissimilarities in other respects should not defeat collective treatment. Cf. Aragon v. Republic Silver State Disposal, Inc. , 292 F.3d 654, 659-60 (9th Cir. 2002) (applying Title VII's "similarly situated" standard, and looking for evidence of similarities material to the plaintiff's specific allegation of discrimination). In considering the "similarly situated" requirement in this case, both the City and the Officers rely heavily on the Supreme Court's assessment, in Wal-Mart Stores, Inc. v. Dukes , 564 U.S. 338, 131 S.Ct. 2541, 180 L.Ed.2d 374 (2011), of the commonality requirement of Rule 23. The analogy is not entirely misplaced. The "common question" requirement within Rule 23, like the similarly phrased requirements within Rules 20 and 42, bears a close resemblance to the "similarly situated" requirement of section 216(b). See Fed. R. Civ. P. 23(a)(2) ; see also Fed. R. Civ. P. 20(a)(1)(B) ; Fed. R. Civ. P. 42(a). All these requirements serve comparable ends; their purpose is not simply to identify shared issues of law or fact of some kind , but to identify those shared issues that will collectively advance the prosecution of multiple claims in a joint proceeding. As the Supreme Court stated in Dukes , "[w]hat matters ... is not the raising of common 'questions'-even in droves-but, rather the capacity of a classwide proceeding to generate common answers apt to drive the resolution of the litigation." Dukes , 564 U.S. at 350, 131 S.Ct. 2541 (emphasis omitted) (quoting Nagareda, Class Certification in the Age of Aggregate Proof , 84 N.Y.U. L. Rev. 97, 132 (2009) ). Similarly, in the collective action context, what matters is not just any similarity between party plaintiffs, but a legal or factual similarity material to the resolution of the party plaintiffs' claims, in the sense of having the potential to advance these claims, collectively, to some resolution. See Calderone , 838 F.3d at 1103 ; Symczyk , 656 F.3d at 199-200. However, for the reasons discussed above, broad reliance on Dukes and other class action case law remains unwise in the collective action context, as it risks importing into the FLSA, contrary to its terms, the "rigorous analysis" uniquely applied under Rule 23 to purely representative litigation, Dukes , 564 U.S. at 350-51, 131 S.Ct. 2541, as well as factors-for example, adequacy, superiority, predominance-with no foundation in the language of section 216(b). See 7B Fed. Prac. & Proc. Civ. § 1807 (observing that district courts have "uniformly" rejected the argument that Dukes affects the FLSA's "similarly situated" requirement). Under section 216(b), if the party plaintiffs are similar in some respects material to the disposition of their claims, collective treatment may be to that extent appropriate, as it may to that extent facilitate the collective litigation of the party plaintiffs' claims. District courts have ample experience managing cases in this way. For example, Rule 42, which offers a closer analogy to the collective mechanism than Rule 23, already provides for the possibility of partial consolidation for trial, to the extent separate actions involve common questions of law or fact. Fed. R. Civ. P. 42(a)(1). The second flaw of the ad hoc test lies in its "fairness and procedural considerations" prong. Such an open-ended inquiry into the procedural benefits of collective action invites courts to import, through a back door, requirements with no application to the FLSA-for example, the Rule 23(b)(3) requirements of adequacy of representation, superiority of the group litigation mechanism, or predominance of common questions. Again, the FLSA does not give district courts discretion to reject collectives that meet the statute's few, enumerated requirements. Zavala v. Wal Mart Stores Inc. , 691 F.3d 527, 535 (3d Cir. 2012). To the contrary, the FLSA gives party plaintiffs the power to decide in what form they wish to proceed, for "Congress has stated its policy that [party] plaintiffs should have the opportunity to proceed collectively." Hoffmann-La Roche , 493 U.S. at 170, 110 S.Ct. 482. That is not to say that "procedural considerations" can never justify decertification. A "collective" action in which, as a practical matter, no material dispute truly could be heard on a collective basis would hardly be consistent with the FLSA's remedial purpose. But if the party plaintiffs' FLSA right to choose collective litigation has any force, "procedural considerations" must mean more than the inconvenience, from the court's or defendant's viewpoint, of the party plaintiffs' choice. Importantly, the theoretical alternative to collective litigation is the possible proliferation of individual actions-in the present case, thousands of individual actions-litigated seriatim. See Morgan , 551 F.3d at 1265. Accordingly, at this second step of the ad hoc test, decertification of a collective action of otherwise similarly situated plaintiffs cannot be permitted unless the collective mechanism is truly infeasible. c. The district court's analysis The district court's approach to decertification in the present case offers a useful example of both flaws of the ad hoc test. The Officers' position was that there was a tacit, Department-wide policy discouraging the reporting of earned overtime. If that allegation were adequately supported by the record, the "similarly situated" requirement would have been met. The Officers would have been alike in a way material to their litigation, as proving (or failing to prove) the existence of such a Department policy would have affected the ultimate findings regarding the occurrence of unpaid overtime and the City's knowledge of it, see 29 C.F.R. § 785.11, thus collectively advancing the litigation. In applying the ad hoc test, however, the district court focused less on whether there was adequate evidentiary support for the posited policy and more on the overall sameness of the Officers' employment circumstances. For example, the district court emphasized that Officers worked on different tasks, in different divisions, and under different supervisors. Those distinctions would not have mattered to the determination of liability if it were proven, as claimed, that the Department had an overall policy against submitting small overtime claims. See Morgan , 551 F.3d at 1264. A systemic policy is no less common across the collective if those subject to it are affected at different times, at different places, in different ways, or to different degrees. See, e.g. , Klimchak v. Cardrona, Inc. , No. CV-09-04311 (SJF)(ARL), 2011 WL 1120463, at *5 (E.D.N.Y. Mar. 24, 2011) ("[I]f defendants had a policy or practice of not paying overtime compensation to any of its laborers, whether full-time or part-time, union member or non-union member, all of those employees would be similarly situated for purposes of this analysis."). The district court emphasized also that the Officers worked different hours and claimed overtime of different amounts, including some amounts that might have been de minimis. But those distinctions go to the individualized calculation of damages or the individualized application of defenses. Such distinctions do not preclude collective treatment for the purpose of resolving the common issue that does exist, and that must be answered in the first instance. See, e.g. , Bouaphakeo v. Tyson Foods, Inc. , 765 F.3d 791, 797 (8th Cir. 2014), aff'd , --- U.S. ----, 136 S.Ct. 1036, 194 L.Ed.2d 124 (2016). Nor are individualized damages calculations inherently inconsistent with a collective action. In the wage-and-hour context, if a common question regarding the employer's liability is answered in the plaintiffs' favor, individualized calculations of work hours may readily be addressed with any of the practices developed to deal with Rule 23 classes facing similar issues. See Jimenez v. Allstate Ins. Co. , 765 F.3d 1161, 1167 (9th Cir. 2014). "[T]he amount of damages is invariably an individual question and does not defeat class action treatment." Leyva v. Medline Indus. Inc. , 716 F.3d 510, 514 (9th Cir. 2013) (quoting Blackie , 524 F.2d at 905 ). Individual damages amounts cannot defeat collective treatment under the more forgiving standard of section 216(b) either. In effect, using the ad hoc test, with its focus on differences rather than similarities among the party plaintiffs, improperly led the district court into an approach that treats difference as disqualifying, rather than one that treats the requisite kind of similarity as the basis for allowing partially distinct cases to proceed together. In sum, we reject both extant approaches to the FLSA's "similarly situated" requirement. We reject the minority approach because it is founded on an untenable analogy to class action practice and Rule 23. We reject the majority approach-at least as it is typically articulated -because it inadequately accounts for the meaning of "similarly situated" in the FLSA context and improperly sanctions the decertification of collective actions the district court finds procedurally challenging. Party plaintiffs are similarly situated, and may proceed in a collective, to the extent they share a similar issue of law or fact material to the disposition of their FLSA claims. The district court may be able to decertify where conditions make the collective mechanism truly infeasible, but it cannot reject the party plaintiffs' choice to proceed collectively based on its perception of likely inconvenience. 3 We turn to the standard the district court should apply in evaluating a post-discovery motion for decertification. Determining the proper legal standard is a question of law, so we proceed de novo. United States v. Hinkson , 585 F.3d 1247, 1261-62 (9th Cir. 2009) (en banc). Because preliminary certification is not challenged in this case, we address only the standard the district court should apply to post-discovery decertification. We conclude that, in a case such as this one, in which decertification overlaps with the merits of the underlying FLSA claims, the summary judgm