7.2 Rule 23 Class Certification Requirements

Updated 2017 by Sarah Somers

Rules 23(a) and (b) of the Federal Rules of Civil Procedure govern the requirements for class certification. Rule 23(a) sets forth four threshold requirements for class certification, each of which must be met: (1) the class is so numerous that joinder of class members is impracticable (numerosity); (2) there are questions of law or fact common to the class (commonality); (3) the claims or defenses of the class representatives are typical of those of the class (typicality); and (4) the class representatives will fairly and adequately protect the interests of the class (adequacy).

To certify a class, a court must also find that one of the following requirements, set forth in Rule 23(b), are met: (1) that prosecution of separate actions risks either inconsistent adjudications which would establish incompatible standards of conduct for the defendant or would as a practical matter be dispositive of the interests of others; (2) that defendants have acted or refused to act on grounds generally applicable to the class; or (3) that there are common questions of law or fact that predominate over any individual class member’s questions and that a class action is superior to other methods of adjudication.

Before filing a case as a class action, counsel should analyze carefully if and how the case meets the Rule 23(a) and (b) requirements. The complaint should plead specifically each of the Rule 23 requirements rather than merely parrot the language of Rule 23. Indeed, many local rules require that class action allegations contain specific information regarding the class, such as an estimate of the number of persons in the class.1 In addition to Rule 23(a) and (b), as explained below, courts have added implicit requirements for class certification. The courts require (1) that a definable class exists, (2) the named representatives are members of that class, and (3) the claim of the class is live, rather than moot. 

The Supreme Court has recently made it clear that plaintiffs must not merely plead the existence of the Rule 23 requirements, but prove them.2 As a result, district courts must perform a "rigorous" analysis to determine whether the Rule 23(a) prerequisites are satisfied.3 In Wal-Mart Stores v. Dukes, the Court cast aside the frequently cited proposition that courts are not to consider the merits of the plaintiff’s underlying claim in the analysis,4 and observed that the rigorous analysis required frequently will evaluate the merits of the claims presented.5  Thus, in Wal-Mart Stores, the Court considered the merits of the plaintiffs' Title VII claims because of the overlap of commonality and allegations of a pattern and practice of discrimination.6 Subsequently, however, in Amgen, Inc. v. Connecticut Retirement Plans and Trust Funds, the Court cautioned that “free-ranging merits inquiries” are not appropriate under Rule 23 and that “[m]erits questions may be considered to the extent—but only to the extent—that they are relevant to determining whether the Rule 23 prerequisites for class certification are satisfied.”7

The plaintiff has the burden of proving that the requirements of Rule 23 are met.8 Factual determinations necessary to the certification ruling must be proven by a preponderance of the evidence.9 Courts of Appeals generally review the district court’s decision to certify or to deny certification of the class for abuse of discretion.10 A court abuses its discretion if its certification order is premised on legal error.11 Courts are less deferential to the denial of certifications than they are to the granting of them.12  

7.2.A. Rule 23(a) Requirements

The four preliminary requirements for class certification—numerosity, commonality, typicality and adequacy of representation—must all be met.

7.2.A.1. Numerosity

The numerosity requirement of Rule 23 does not focus exclusively on the number of members of the putative class, but, instead, on the impracticality of individual joinder.13 The courts apply no strict numerical test for determining impracticality of joinder, although, as a general benchmark, classes of less than 20 are insufficiently numerous and classes of 40 or more satisfy the numerosity requirement.14 Rather than relying only on numbers, courts must examine the specific facts of each case.15

Although a large number of putative class members may suffice to prove numerosity, other factors are considered in determining whether joinder is impracticable.16 These factors include the ease of identifying and finding individual class members, geographical separation, fluid composition of class population, size of individual claims, individual ability and motivation to bring separate actions, and the nature of the claims raised and relief sought.17 but will not resort to speculation.18 If the size and impracticality of joinder appear to be a problem in a given case, adjusting the class definition may resolve the issue by, for example, eliminating subclasses (each subclass must independently meet the numerosity requirements) or including persons who will be affected in the future.19

7.2.A.2. Commonality

Plaintiffs’ grievances generally must share a common question of law or fact.20 Rule 23 does not require that all questions of law or all questions of fact be common to all class members.21 In fact, only one question of law or fact must be common to the proposed class.22 Some factual differences among class members do not defeat commonality.23 Class actions that seek class-wide injunctive or declaratory relief "by their very nature present common questions of law and fact."24  

However, allegations that the common question of law or fact is tied to systemic violations of law have recently drawn closer scrutiny.25 In Lightfoot v. District of Columbia, for example, the plaintiff class alleged that the government and its contractor terminated the benefits of disabled city workers without providing them a pre-deprivation opportunity to challenge the termination. The court decertified the class following receipt of voluminous summary judgment filings when it concluded the procedural due process violations were the result of different practices which did not uniformly pervade the class as a whole. The court held that plaintiffs were required to identify more specifically a particular policy or custom that both violates due process and is common to the class.26

The Supreme Court addressed a similar commonality issue in the Title VII context in Wal-Mart Stores v. Dukes.27   In Wal-Mart Stores, as framed by the majority, the plaintiffs contended that local managers wielded substantial discretion over pay and promotion that had a disparate impact on women because this discretion was exercised within a corporate culture of discrimination of which Wal-Mart was aware but did nothing to stop.  This common discriminatory practice adversely affected all female employees. The Court took issue with defining commonality at a high level of generality:

Quite obviously, the mere claim by employees of the same company that they have suffered a Title VII injury, or even a disparate-impact Title VII injury, gives no cause to believe that all their claims can productively be litigated at  once. Their claims must depend upon a common contention—for example, the assertion of discriminatory bias on the part of the same supervisor. That common contention, moreover, must be of such a nature that it is capable of classwide resolution—which means that determination of its truth or falsity will resolve an issue that is central to the validity of each one of the claims in one stroke.28

The Court found that the plaintiffs had established the existence of a corporate policy: delegating to local managers decisionmaking authority over pay and promotions.  But, it essentially concluded that such delegation was at odds with commonality.  What was required was a showing that local managers exercised this discretion in a common way.  National and regional disparities in pay and promotion between men and women fell short of that because they failed to show the store-by-store differences.  In short, the plaintiffs failed to demonstrate commonality because they could point to no specific employment practice that directly affected all women at Wal-Mart.29 As anticipated, Wal-Mart Stores has set a higher bar for establishing commonality. However, public interest lawyers have had post Wal-Mart success, particularly in (b)(2) classes.30

Commonality may be demonstrated by expert opinion and statistical evidence.  However, Wal-Mart Stores may have made doing so more difficult. The Court demanded "significant proof" of a policy of discrimination and was quite critical of the plaintiff's expert who attempted to supply such proof, while expressing a view that such experts must meet the requirements of Daubert v. Merrell Dow.31 Affidavits from class members containing anecdotal evidence of harm may also be used to support commonality, but there, too, Wal-Mart set a high bar: the Court found insufficient 120 affidavits which represented a very small percentage of class members and only a portion of the nation.32 If the proposed class definition fails to establish commonality, the court may redefine or limit the class,33  or create subclasses.34

The Supreme Court, however, recently decided an important Rule 23(b)(3) class action case, Tyson Foods, Inc. v. Bouaphakeo,35 which, while focusing on the Rule’s predominance inquiry, is significant on the issue on commonality because, distinguishing Wal-Mart, it refused to bar the use of representative evidence in establishing liability. The case dealt with compensable time spent by factory employees in donning and doffing protective uniforms, time that the employer did not record. As a result, the plaintiffs retained an expert who examined a representative sample of employees and determined the average time devoted to these activities. Tyson Foods argued that the time each worker devoted to donning and doffing and whether that time pushed them to overtime status were individual, not common class, questions. As a result, it urged the Court to bar all use of representative evidence in class actions.                    

The Court rejected that request, in part because of the nature of wage-payment cases. It held that whether a representative or statistical sample can permissibly be used to establish class-wide liability depends on the elements of the claim and purpose of the sampling.36 In the context of wage-payment cases, when the employer violates its duty of recording time worked, the employee may show that time by “just and reasonable inference.”37 Because of that doctrine, here, had a class member pursued an individual action, it could have used representative sampling evidence. As the Court explained, “[i]f the sample could have sustained a reasonable jury finding as to hours worked in each employee’s individual action, that sample is a permissible means of establishing the employees’ hours worked in a class action.”38 

That distinguished Wal-Mart, which foundered on commonality rather than Rule 23(b)(3)’s predominance prong. In Bouaphakeo, a representative sample of all employees who worked at the same plant doing similar work was relevant to the hours individuals donned and doffed their protective gear. In Wal-Mart, in contrast, plaintiffs “proposed to use representative evidence as a means of overcoming this absence of a common policy. . . . Since the Court held that the employees were not similarly situated, none of them could have prevailed in an individual suit by relying on depositions detailing the ways in which other employees were discriminated against by their particular store managers.”39

7.2.A.3. Typicality

While commonality and typicality "tend to merge,"40 the commonality requirement focuses on the common thread among all class members, and the typicality requirement focuses on the named plaintiff. In the leading case in this area, General Telephone Company of the Southwest v. Falcon, the Supreme Court held that the class representative had to “possess the same interest and suffer the same injury as the class members.”41 The typicality requirement centers on “whether the class representative’s claims have the same essential characteristics as those of the putative class. If the claims arise from a similar course of conduct and share the same legal theory, factual differences will not defeat typicality.”42

Put another way, typicality can be determined by whether there is a sufficient nexus between the claims of the named representatives and those of the class.43 As with commonality, factual differences do not defeat typicality if the course of conduct and the claims are based on the same legal theory.44

However, typicality is not present when a class representative's claim may be challenged by a unique defense, which may preoccupy the putative class representative and potentially place her interests ahead of those of the class.45 In addition, typicality generally requires at least one named plaintiff to have claims against each defendant, otherwise there is no standing against defendants with no claims against them.46 There are two exceptions to this principle: when the defendants conspired to harm the class representative and when the defendants are "juridically linked" in the sense that a class action is preferred over multiple actions.47

7.2.A.4. Adequacy of Representation—Class Representatives and Counsel

Rule 23 (a)(4) requires a class representative to represent fairly and adequately the interests of absent class members. As with other aspects of Rule 23, due process governs the determination of adequacy of representation.48 By assuring adequacy of representation, Rule 23 permits class judgments to bind absent class members.49 The requirement of adequate representation applies to both the plaintiffs and counsel. The 2003 Amendments, which added subsection (g) to Rule 23, have changed somewhat the inquiry into adequate representation of counsel.

First, the court asks whether the named plaintiffs will serve as adequate class representatives. By separating the inquiry into adequacy of representation from the issues of commonality and typicality, the rule requires a critical assessment of issues on which the named plaintiffs and any part of the class might disagree.50 Class certification is improper when the interests of the representative party and the class conflict, although they need not be identical. In a leading Supreme Court case in this area, a class was decertified upon a finding that the claims of the named representatives were not aligned with those of the other class members. In that case, putative class members were all exposed to asbestos, but many members suffered injuries completely different than those suffered by other class members.51 Defendants often attempt to defeat class certification by making allegations of antagonistic interests between the named representatives and the remainder of the class.

Conflicts can usually be averted by counsel vigilantly assessing all interests involved on a regular basis, informing the court of any potential conflicts when they arise, and asking the court to certify subclasses and appoint independent counsel to represent the varying interests in the conflict.52 In addition, a judge may order notice to all class members informing them of the right to intervene to oppose the named plaintiff’s position.53 Or, the court may define the class in a more limited way to avoid conflicts.54

In addition to showing a lack of conflict with class members, the named plaintiff must also evidence a willingness to prosecute the class claims actively. Thus, in a case in which the named plaintiff failed to file for class certification for two and a half years, the court found that she failed to protect the interests of the proposed class.55 Adequate representation by the named plaintiff generally should not, however, include an assessment of plaintiff’s financial resources, unless lack of financial resources is relevant to the named plaintiff’s willingness or ability to fund the litigation or represent the class.56

The 2003 amendments to Rule 23 added subsection (g), which requires the court to appoint class counsel and now explicitly mandates that counsel fairly and adequately represent the class. Under Rule 23(g), certification of the class precedes appointment of adequate counsel.57 Rule 23(g)(1)(A) lists the factors that the court must consider in appointing class counsel. They include pre-filing investigation, experience in class actions or similar claims, knowledge of law, and resources that counsel will commit to representing the class.58

When evaluating adequate representation of counsel, zeal and competency of counsel are important factors. Zeal and competency of counsel for the class are initially determined on the basis of the experience of the lawyer or the legal organization for whom the lawyer works and the quality of initial pleadings.59 Indeed, the court examines the conduct of counsel in the case to date and in other class actions to determine if the representation is adequate.60  For example, failing to move promptly for class certification could be viewed as evidence of lack of adequate class representation.61

Having more than one counsel in class actions is advisable as a rule. If one has not handled a class action, then co-counseling with experienced counsel is necessary. Although an initial determination of counsel’s adequacy to represent the class aggressively is necessary to certify the class, the court has flexibility to decertify the class later based on evidence of inadequate representation in discovery.62

7.2.B. Implicit Requirements

The courts have added some “implicit” requirements for the putative class to meet in order to obtain class certification: (1) a definable class exists, (2) the named representatives have standing, and (3) the claim of the class is live, not moot.

7.2.B.1. Existence of a Definable Class

In order to obtain certification, a class must be sufficiently definable or ascertainable.63 The court must determine that defining the class is both possible and feasible. This means that a court must be able to identify all members of the class by using objective criteria.64 If a class is defined in terms of vague or subjective criteria, such as the members’ states of mind, the court has no objective means with which to identify the members of the class and therefore will not certify the class.65 Even if the class is defined in terms of objective criteria, those criteria may be too difficult for the court to apply feasibly and the court may refuse to certify the class.66

If a class is so broad that it includes members who would not have standing to bring an action individually, the court will not certify the class. For example, in an action by Latino inmates against a prison for not providing Spanish-speaking staff, the court would not certify a class comprised of all of the Latino inmates. Some of those Latino inmates spoke English and would not have suffered any injury; thus, they did not have standing to sue.67

Although members of a class must be easily identifiable for the court, a class may be certified even though the court cannot identify every potential member of the class at the moment of certification. Thus, a class may obtain certification even if it is of such a nature that it will inevitably need to add or drop members during the course of the action.68

Upon finding that a class is not sufficiently definable, the court may limit or redefine the class using its authority under Rule 23(c)(4),69 or it can deny class certification and allow the named members to proceed individually.70 A precisely defined class is necessary in order to analyze whether that class meets the other requirements for certification under Rule 23. Further, a court must have a precise class definition in order to be able to determine which individuals are entitled to notice or relief as well as which individuals will be bound by a judgment.

7.2.B.2. Class Representatives Must Be Part of the Defined Class

In order to obtain certification, the named representatives must be class members. That is, each named representative must have proper standing and must have the same interest and injury as other members of the class. Moreover, for each named defendant, at least one named plaintiff must be able to allege injury traceable to the defendant. 71 For example, plaintiffs in an employment discrimination suit would need to be qualified for the job positions at issue in order to act as named representatives of the people against whom an employer has allegedly discriminated.72 

There is disagreement among courts, however, as to whether so-called “no injury” class actions, in which some of the putative plaintiffs have not been injured by the challenged conduct, may be maintained. These can be, for example, toxic tort cases, in which putative plaintiffs have been exposed to an alleged toxin but not showing injury, consumer cases in which putative plaintiffs have purchased an allegedly defective product that has not yet failed, or employment cases in which plaintiffs sue for overtime pay but not all class members have worked overtime. Some courts of appeal have allowed such cases to proceed, while others have not.73

7.2.B.3. A Live Claim

In order for the class to obtain certification, courts require a claim to be live, not moot. If it is not a live claim, the court will dismiss the suit unless a new class representative with a live claim steps forward. However, under certain circumstances, an individual with a moot claim may still serve as a class representative. For example, if a class representative’s claim becomes moot after a class is certified, the entire class action does not become moot as a result.74 If the court denies class certification and the named representative’s claim later becomes moot, the class representative may still appeal the denial of certification.75

There are a number of exceptions to the mootness doctrine. An individual whose claim is moot may continue to serve as a class representative if the individual’s claim is “capable of repetition yet evading review.” In addition, there are exceptions for claims that are "inherently transitory" and when defendants "pick off" named plaintiffs in an attempt to moot claims. In such cases an individual with a moot claim may serve as a class representative even if the claim became moot before class certification.76

In Wilson v. Gordon, plaintiffs alleged that delays in application processing and failure to provide a hearing on their delayed applications violated Medicaid provisions and the Due Process Clause. The district court certified a class and granted a preliminary injunction and the state appealed. Because the named plaintiffs had been enrolled in the Medicaid program the day before the hearing, the state agency argued that their claims were moot and class should not have been certified. The district court rejected this argument, finding that exceptions to the mootness doctrine applied.  A divided panel of the Sixth Circuit affirmed and held that the “inherently transitory” and “picking off” exceptions applied. The first exception applied because the duration of plaintiffs’ claims were tenuous and they did not know how long their claims for injunctive relief would remain live. The second applied because the evidence showed that the state agency had strategically mooted the plaintiffs’ claims.77

7.2.C. Rule 23(b) Requirements

In addition to meeting all four Rule 23(a) requirements, a class action must meet one of the three requirements of Rule 23(b).

7.2.C.1. Rule 23(b)(1) Classes

A Rule 23(b)(1)(A) action is intended to protect the defendants from inconsistent adjudications imposing incompatible obligations that might result from independent actions brought by individual plaintiffs. The Advisory Committee explained:  "One person may have rights against, or be under duties toward, numerous persons constituting a class and be so positioned that conflicting or varying adjudications in lawsuits with individual members of the class might establish incompatible standards to govern his conduct. The class action device can be used effectively to obviate the actual or virtual dilemma which would thus confront the party opposing the class."78 It offered an example:

Separate actions by individuals against a municipality to declare a bond issue invalid or condition or limit it, to prevent or limit the making of a particular appropriation or to compel or invalidate an assessment, might create a risk of inconsistent or varying determinations. In the same way, individual litigations of the rights and duties of riparian owners, or of landowners’ rights and duties respecting a claimed nuisance, could create a possibility of incompatible adjudications. Actions by or against a class provide a remedy and fair means of achieving unitary adjudication.79

Generally, the prospect of inconsistent injunctive relief satisfies this rule while the possibility of varying monetary awards does not.80

By contrast, a Rule 23(b)(1)(B) action is designed to protect absent class members from litigation that could impair “their ability to protect their interests.” The Advisory Committee explained that:

In various situations an adjudication as to one or more members of the class will necessarily or probably have an adverse practical effect on the interests of other members who should therefore be represented in the lawsuit. This is plainly the case when claims are made by numerous persons against a fund insufficient to satisfy all claims. A class action by or against representative members to settle the validity of the claims as a whole, or in groups, followed by separate proof of the amount of each valid claim and proportionate distribution of the fund, meets the problem.81

The Supreme Court’s most recent word on Rule 23(b)(1)(B) class actions in the limited fund context is Ortiz v. Fibreboard Corporation.82 The Court held that certification under this provision requires that 1) the fund is inadequate to pay all claims, 2) all the fund is to be devoted to paying the claims and 3) the class members are treated equitably among themselves.83 These requirements are difficult to satisfy; an excellent recent example is Katrina Canal Breaches Litigation v. Board of Commissioners, in which the Fifth Circuit reversed the certification of a limited fund class for settlement purposes in a Katrina-related case, holding that the settlement was not fair or reasonable and did not equitably distribute funds among class members.84

7.2.C.2. Rule 23(b)(2) Classes

Class certification under Rule 23(b)(2) is far more common than (b)(1) classes and the traditional class action tool for poverty lawyers. Under Rule 23(b)(2), the class must show that the defendant acted in a way “generally applicable” to class members, making classwide declaratory and injunctive relief appropriate. In Wal-Mart Stores, the Court held that Rule 23(b)(2) is only satisfied when 

a single injunction or declaratory judgment would provide relief to each member of the class. It does not authorize class certification when each individual class member would be entitled to a different injunction or declaratory judgment against the defendant.85

Unlike with the commonality requirement of Rule 23(a), factual differences between the named plaintiffs following the classwide injunctive relief may sometimes defeat certification.86 While manageability is not explicitly required in a Rule 23(b)(2) class, courts sometimes consider it nonetheless.87 Certification is unlikely if the putative class seeks particularized relief for each class member.

In requesting Rule 23(b)(2) certification for injunctive relief, the named plaintiffs must have standing for each type of relief requested.88 Thus, when a named plaintiff does not have standing to seek injunctive relief, Rule 23(b)(2) class certification is denied.89 Rule 23(b)(2) class members require no notice (although the court may direct notice in unusual cases) and have no opt-out rights.90

In cases where compensatory damages as well as injunctive or declaratory relief are sought, courts have struggled with determining whether (b)(2) certification is appropriate. This is particularly significant in employment discrimination cases. Since the 1991 amendments to the Civil Rights Act, Title VII plaintiffs have been permitted to recover compensatory damages.91 These damages include relief for a wide range of losses including future pecuniary losses, emotional pain, suffering, nonpecuniary damages (Section 1981a(b)(3)); and punitive damages (Section 1981a(b)(1)(2)). In Wal-Mart Stores v. Dukes, the Court resolved that issue in large part by holding that a Rule 23(b)(2) class is not appropriate when the class seeks individualized monetary damages for class members.92 Further, the Court rejected the notion that Rule 23(b)(2) classes are appropriate so long as monetary relief does not "predominate" over injunctive or declaratory relief.93

The Court noted, with apparent approval, the holding in Allison v. Citgo Petroleum Corporation94  that Rule 23(b)(2) certification was appropriate only if compensatory relief was merely "incidental" to the equitable relief sought in Title VII cases.95 Such would be the case if "damages . . . flow directly from liability to the class as a whole on the claims forming the basis of the injunctive or declaratory relief."96 This was appropriate because such "incidental damage should not require additional hearings to resolve the disparate merits of each individual's case; it should neither introduce new substantial legal or factual issues, nor entail complex individualized determinations."97 The Court in Wal-Mart said that it did not have to decide whether the award of such incidental damages could comport with Due Process because the plaintiffs did not and could not argue that the monetary relief sought satisfied the "incidental" test.98 In the Title VII context, the Court held that principles of Due Process require individualized hearings on eligibility for backpay.99

 Increasingly, courts are finding an implicit "cohesiveness" requirement in Rule 23(b)(2).100 The Lightfoot v. District of Columbia case fell victim to such a requirement, found nowhere in the Rule.  There, the court found that differences in the amounts of time class members had between notice and termination, all alleged to be constitutionally insufficient, yielded a conclusion that the class was not sufficiently cohesive to warrant class certification.101 The irony of such a cohesiveness requirement in Rule 23(b)(2) cases is seemingly arbitrary deviations from a common unwritten custom and practice can preclude class certification.

7.2.C.3. Rule 23(b)(3) Classes

Rule 23(b)(3) permits certification under subdivision (b)(3) when the primary relief sought is damages. In such a case, Rule 23(b)(3) requires that the common questions of law and fact predominate over any individual questions and that a class action be superior to other methods for fair and efficient resolution of the conflict.102 The district court has broad discretion in determining whether common questions predominate and whether a class action is manageable, using the factors set forth in Fed. R. Civ. P. 23(b)(3)(A-D).

Rule 23(b)(3) class actions are expensive and time-consuming, requiring notice to all class members;103 opportunity for opt-out; more expensive and extensive discovery; and individual representation post-judgment. As such, counsel should carefully consider the resources required for litigation before undertaking representation of a Rule 23(b)(3) class. Whenever possible, certification should be sought under subdivision (b)(1) or (b)(2).

 Updated 2017 by Sarah Somers