In re: Avandia Marketing v.

PRECEDENTIAL UNITED STATES COURT OF APPEALS FOR THE THIRD CIRCUIT _____________ No. 25-2278 In re: AVANDIA MARKETING, SALES PRACTICES and PRODUCTS LIABILITY LITIGATION, GlaxoSmithKline LLC, Appellant On Appeal from the United States District Court for the Eastern District of Pennsylvania (D.C. Civil Action No. 2:07-md-01871) District Judge: Honorable Cynthia M. Rufe Argued on February 26, 2026 Before: SHWARTZ, MONTGOMERY-REEVES, and AMBRO, Circuit Judges (Opinion filed July 21, 2026) Devora W. Allon (Argued) Jay P. Lefkowitz Kevin M. Neylan, Jr. Kirkland & Ellis 601 Lexington Avenue New York, NY 10022 Cole Carter Kirkland & Ellis 333 W Wolf Point Plaza Chicago, IL 60654 Kyle A. Dolinsky Troutman Pepper Locke 11682 El Camino Real Suite 400 San Diego, CA 92130 Robin P. Sumner Troutman Pepper Locke 3000 Two Logan Square 18th and Arch Streets Philadelphia, PA 19103 Counsel for Appellant Hannah W. Brennan Erin C. Burns Thomas M. Sobol (Argued) Hagens Berman Sobol Shapiro One Faneuil Hall Square 5th Floor Boston, MA 02109 2 Edwina Bullard Clarke David Zimmer Zimmer Citron & Clarke 711 Atlantic Avenue Sixth Floor Boston, MA 02111 Joseph H. Meltzer Jonathan F. Neumann Terence S. Ziegler Kessler Topaz Meltzer & Check 280 King of Prussia Road Radnor, PA 19087 Julia Solomon-Strauss Zimmer Citron & Clarke 14 Ridge Square NW Suite 328 Washington, DC 20016 Anne-Marie J. De Bartolomeo Kaplan Fox & Kilsheimer 1999 Harrison Street Suite 1501 Oakland, CA 94612 Counsel for Appellees OPINION OF THE COURT 3 AMBRO, Circuit Judge We do not presume in law that x caused y merely because x happened first. The connection might be causal. But it might be coincidental. Or some z might be responsible for x and y alike. As statisticians emphasize, correlation alone does not prove causation. One method experts have developed for distinguishing true causation from mere correlation is multiple regression analysis. It can “define statistically the relationship between a dependent variable (e.g., salary) and one or more independent variables (e.g., education or work experience),” enabling us to conclude with confidence that the latter is the reason for the former (or is at least one reason). Weisfeld v. Sun Chem. Corp., 84 F. App’x 257, 261 n.3 (Table) (3d Cir. 2004); see also 1 David L. Faigman et al., Mod. Sci. Evidence § 6.1 (2025-2026 ed.). It can also enable us “to control for other independent variables” so we can rule out competing explanations (or at least rule them unlikely). Id. And it can quantify how much of a difference the cause makes to the effect. Thus, although it may be that “[t]he only empirical facts . . . we can discover about the world are facts about correlation,” regression analysis can justify the “inference” of causation by “testing and attempted invalidation” of other “causal hypotheses.” See United States v. Mosley, 454 F.3d 249, 266 (3d Cir. 2006). This appeal raises this issue and more. Third-party payors (“TPPs”) who covered prescriptions for the diabetes medication Avandia brought a putative class action against the manufacturer, GlaxoSmithKline LLC (“GSK”), for misrepresenting the drug’s cardiovascular risks and benefits. GSK’s misrepresentations, they claim, caused more health care 4 providers (we use “physicians,” “prescribers,” and similar terms interchangeably) to prescribe Avandia than cheaper alternatives. That, in turn, allegedly caused these TPPs to reimburse patients for Avandia that otherwise would not have been prescribed. GSK challenges the District Court’s certification of the class. It argues the proposed class is not ascertainable because there is not enough evidence to identify which TPPs reimbursed members for the drug. And it contends common issues do not predominate on causation because the plaintiffs lack class-wide evidence GSK’s fraud caused them to cover more Avandia prescriptions than they would have otherwise. Their evidence, GSK contends, shows only correlation, not causation. Though we hold the proposed class is ascertainable, we part with the District Court’s ruling that common issues would predominate on causation. We join the other circuits that have addressed this issue—the First, Second, and Ninth—and conclude that plaintiffs in a pharmaceutical fraud RICO class action may use statistical evidence to prove the defendant was responsible for their injuries when the evidence can establish causation, not merely correlation. The Plans’ statistical evidence does not satisfy this standard yet. After laying out the type of statistical evidence that may be used to prove causation in a case like this one, we vacate the District Court’s certification of the class and remand for further fact-finding on predominance under the clarified standard. I. BACKGROUND 5  In 1999, the Food and Drug Administration (“FDA”) approved a new treatment for Type II diabetes: Avandia.1 GSK, its developer, sold it for a higher price than the drug’s older rivals, like metformin. But GSK said Avandia was worth the premium. According to the pharmaceutical company’s marketing, Avandia would not help patients manage only their blood sugar. It would also reduce their cardiovascular risks. To diabetics, that mattered. Roughly two-thirds of diabetes patients die of cardiovascular conditions. So despite Avandia’s higher cost, health insurers added it to their formularies and reimbursed patients. In the years following FDA approval, Avandia prescriptions soared. In 2006 alone, GSK sold $2.2 billion of the drug in the United States. Meanwhile, GSK’s own research began to suggest an inconvenient truth: the drug actually posed distinctive cardiovascular risks. In 2004, GSK began an internal meta- analysis, that is, a study of what existing clinical trials indicated about Avandia’s cardiovascular profile. See In re Paoli R.R. Yard PCB Litig., 916 F.2d 829, 856 (3d Cir. 1990) (defining as “meta-analysis” a study “combining the results of different . . . studies done by other scientists, and re-analyzing the combined data to see if the data, in toto, renders different results than the individual studies done with a smaller data sample”). That September, it completed its initial review of those trials, the precursor to the study later dubbed ICT-37. 1 We limit our recitation of the facts, as we have recounted them in two prior precedential opinions in this case. See In re Avandia Mktg., Sales Practices & Prod. Liab. Litig., 804 F.3d 633 (3d Cir. 2015); In re Avandia Mktg., Sales Practices & Prod. Liab. Litig., 945 F.3d 749 (3d Cir. 2019), cert. denied, 141 S. Ct. 265 (Mem). 6 GSK did not complete the meta-analysis and present the results to its safety board as ICT-37 until a year later, September 2005. The conclusion: Avandia was associated with a statistically significant increase of serious ischemic events (compromises of the blood flow to the heart causing heart attack, disability, or death). GSK nonetheless did not immediately update the drug’s label or ask the FDA for permission to do so. In February 2006, GSK completed a new meta-analysis, reexamining the results of the clinical trials it examined in ICT- 37 and evaluating five additional ones. This study, ICT-42, reached the same conclusion: Avandia posed serious cardiovascular risks. In August the same year, the company asked the FDA for permission to add a warning to Avandia’s label, notifying patients that ICT-42 found the drug caused a statistically significant risk of an increase in myocardial ischemic events. In May 2007, GSK also asked to make that warning clearer and more prominent. Then—before the FDA had ruled on either of these requests—the truth reached the public. The New England Journal of Medicine published a study of Avandia by Dr. Steve Nissen (the “Nissen study”). It found Avandia “was associated with a significant increase in the risk of myocardial infarction and with an increase in the risk of death from cardiovascular causes that had borderline significance.” JA 443. The FDA denied GSK’s requests to change the label, then demanded that it make more dramatic changes to address the Nissen study and other emerging research. By the end of 2007, the FDA had directed GSK to add a “black-box warning”2 conveying that 2 Though officially called a “boxed warning,” the term refers to the FDA’s most stringent safety alert communicated through 7 Avandia could cause or exacerbate congestive heart failure and increase the risk of myocardial ischemic events. Prescriptions plummeted. Between 2004 and 2006, doctors prescribed Avandia about 1.2 million times per month. By the end of 2007, that number was below 500,000 prescriptions per month. After over 50 additional clinical trials, the FDA enhanced the black-box warning and restricted distribution of Avandia.3 Consequences followed. In 2012, GSK pled guilty to one count of failing to report clinical data to the FDA and agreed to pay a criminal fine of nearly $250 million. GSK also reached a civil settlement for misrepresenting Avandia’s cardiac risks in violation of the False Claims Act, 31 U.S.C. § 3729, and agreed to pay the federal Government over $500 million. United Food and Commercial Workers Local 1776 and Participating Employers Health and Welfare Fund (“UFCW”), along with J.B. Hunt Transport Services, Inc. (“J.B. Hunt”), provide prescription drug coverage to their members or employees. In 2010, they sued GSK on behalf of a proposed a bold, black-bordered notice atop a drug’s label or package insert. See generally 21 C.F.R. § 201.57(c)(1) (explaining that black-box warnings reveal “[c]ertain contraindications or serious warnings, particularly those that may lead to death or serious injury”). 3 In 2013, the FDA relaxed these restrictions and removed the black-box warning for myocardial ischemic events (blocked blood vessels), but it retained the one for myocardial infarction (heart attack). 8 class of TPPs (the “Plans”) that paid for Avandia, alleging violations of the Racketeer Influenced and Corrupt Organizations Act (“RICO”), 18 U.S.C. § 1962(c), and a host of state laws. Their cases were combined into the In re Avandia Marketing, Sales Practices and Products Liability multi- district litigation. The Plans alleged GSK fraudulently misrepresented Avandia’s true cardiovascular profile, marketing the drug for its supposed cardiovascular benefits while failing to disclose its real cardiovascular risks. In reliance on GSK’s misrepresentations, they included Avandia on their formularies even though the drug cost more than the alternatives and covered more Avandia prescriptions than they would have absent the fraud. GSK moved to dismiss the complaint for failure to state a claim, contending in relevant part that the Plans had failed to allege plausibly they suffered an economic injury and that GSK’s alleged fraud was its proximate cause. In re Avandia Mktg., Sales Practices & Prod. Liab. Litig., 804 F.3d 633, 637 (3d Cir. 2015) (“Avandia I”). The District Court denied the motion as to the RICO claim, holding the plaintiffs plausibly alleged GSK’s misrepresentations about Avandia’s cardiac benefits deprived them of “the substantial savings they would have experienced had they covered cheaper alternatives to Avandia.” Id. We affirmed. Id. at 634. In 2016, GSK moved for summary judgment on the grounds the federal Food, Drug, and Cosmetic Act, 21 U.S.C. Ch. 9, preempted the remaining state law claims and that the Plans had failed to create a genuine dispute of material fact about the existence of a RICO enterprise. In re Avandia Mktg., 9 Sales Practices & Prod. Liab. Litig., 945 F.3d 749, 756 (3d Cir. 2019), cert. denied, 141 S. Ct. 265 (Mem). The District Court granted summary judgment for GSK. Id. We reversed the Court’s order on the state law claims and vacated its order on the RICO claims, holding the Plans were entitled to discovery on the latter. Id. at 752–53. In May 2023, the Plans moved to certify the following class: All entities in the United States of America and its territories, which indirectly purchased, and/or provided reimbursement for some or all of the purchase price for the drugs Avandia, Avandamet, and/or Avandaryl from May 25, 1999 until August 14, 2007.4 Included in the Class are self-insured non- governmental entities and third-party payers that offer insured plans to private individuals and groups. Likewise third-party payers that offer insured plans to government entities including the Federal Employee Program, Managed Medicaid, and Medicare Part D are class members. They also proposed five exclusions: (i) governmental entities other than municipalities and/or local governments with self-funded prescription drug plans; (ii) fully 4 We use Avandia throughout to refer to all three drugs. 10  insured health plans, i.e., plans for which the insurer bears 100% of the risk for the reimbursement obligations to members; (iii) pharmacy benefit managers; (iv) natural person consumers; and (v) employees of [GSK], including its officers or directors, and subsidiaries and affiliates. And they later agreed to narrow the class period to January 1, 2005 to August 14, 2007. In support of their motion for class certification, the Plans moved to introduce two expert reports. The first, from Dr. Meredith Rosenthal, sought to prove causation. She offered two main opinions: (a) GSK’s misrepresentations of Avandia’s health benefits were responsible for a significant portion of the prescriptions the Plans covered; and (b) 41% of prescriptions in the class period would not have happened but for the fraud. Dr. Rosenthal based these conclusions on a multiple regression analysis performed to isolate the causal significance of GSK’s misrepresentations on prescription volume. The Plans introduced the second report, from Dr. Thomas McGuire, to prove damages. Using several models, he estimated damages totaling between $500 million and over $2 billion. As relevant here, one model—the Scenario 1 Step Down Adjustment—assumed the earlier publication of ICT-37 would have caused a similar decline in prescriptions as did the actual publication of the Nissen study. On that assumption, Dr. McGuire calculated damages by applying the percentage decline in prescriptions after that study to the earlier time period and estimated damages of around $1 billion. 11  GSK moved to exclude both reports. In October 2024, after a Daubert hearing, the District Court granted GSK’s motion to exclude the Rosenthal report and granted in part and denied in part its motion to exclude the McGuire report. The Court found Dr. Rosenthal’s opinions unreliable because her regression model deviated from the standards of her field and the deviations were consequential. The model appeared “results-oriented” and particularly susceptible to false positives. In re Avandia Mktg., Sales Pracs. & Prods. Liab. Litig., No. 07-MD-1871, 2024 WL 4582876, at *10–11 (E.D. Pa. Oct. 25, 2024). For instance, not only did it show a statistically significant positive causal relationship between prescription volume and GSK’s promotion of Avandia, it also indicated a statistically significant positive causal relationship between prescription volume and obviously irrelevant variables, like U.S. carbon emissions. So the District Court granted the motion to exclude it. The Court found one of Dr. McGuire’s models unreliable because it depended on Dr. Rosenthal’s opinions and rejected others as unreliable on their own merits. The Court nonetheless left one standing: the Scenario 1 Step Down Adjustment, explained above. The Plans did not appeal the District Court’s evidentiary rulings. In May 2025, the District Court granted the Plans’ motion to certify the class. First, it held the proposed class satisfied the elements of Federal Rule of Civil Procedure 23(a): numerosity, commonality, typicality, and adequacy of representation. GSK did not contest any of the Rule 23(a) issues. Second, the Court ruled that the proposed class satisfied Rule 23(b)(3); in relevant part, it held the Plans established that common questions would predominate and that the proposed class was ascertainable. 12  GSK argued the Plans had not proven common questions would predominate on one element of their RICO claim: causation. The Plans advanced a quantity-effect theory of causation: that GSK’s misrepresentations about Avandia’s cardiac profile led doctors to issue more Avandia prescriptions, which in turn led the Plans to reimburse more prescriptions for this expensive drug. GSK claimed that individualized issues would predominate over common ones. It offered two arguments on this point. First, GSK insisted, questions of reliance are typically individual questions: they turn on why particular doctors issued particular prescriptions to particular patients. Matters like that, it said, are not susceptible to proof by class-wide evidence. The District Court rejected GSK’s argument. It held that the Plans had introduced enough common evidence to justify an inference of “class-wide reliance,” emphasizing two forms of evidence. In re Avandia Mktg., Sales Pracs. & Prods. Liab. Litig., No. 07-MD-1871, 2025 WL 1479618, at *7 (E.D. Pa. May 22, 2025). They had common evidence of the alleged uniform scheme to cover up the drug’s dangers, like marketing materials touting Avandia’s cardiac benefits and testimony from GSK employees about the success of that marketing. And they also had, the District Court found, statistical evidence that GSK’s marketing mattered: internal GSK studies showed that some of its marketing campaigns increased prescriptions. Together, the Court determined, these two forms of common evidence could prove causation.5 5 Along the way, it rejected GSK’s argument that the individualized nature of providers’ decision-making precluded an inference of reliance. As the Court saw the matter, “even though the decision to prescribe Avandia is not ‘one- 13  Second, GSK argued, even if causation could be proven on a class-wide basis by these two forms of common evidence, the evidence here was insufficient. Specifically, according to GSK, its internal studies played a key role in the Plans’ common evidence. But those studies did not isolate causation. And, without causation isolated, they could not serve as class- wide evidence capable of proving it. While the District Court acknowledged GSK’s second argument, it did not articulate the reasons for rejecting it. On ascertainability, the Plans proposed to identify members of the class through a combination of drug purchase records for GSK, a data publisher’s list of entities that paid for Avandia, and a pharmaceutical database, supplemented by affidavits to confirm membership. GSK argued there would not be enough reliable evidence to determine which prospective class members had actually covered Avandia prescriptions. After a careful review of the record, the District Court rejected these concerns. So it held the class was ascertainable and granted the motion to certify. dimensional,’ it is not so subjective that a provider’s reliance cannot be inferred.” Avandia, 2025 WL 1479618, at *8. It acknowledged “there are many factors that impact a provider’s decision to prescribe one medication over another.” Id. Yet it perceived “every provider’s goal when considering whether to prescribe Avandia is largely the same—to treat a patient’s diabetes without otherwise causing harm to their health.” Id. And it thought “providers generally consider the same set of factors” with minimal patient-by-patient variation. Id. 14  In June 2025, GSK petitioned us for permission to appeal under Federal Rule of Civil Procedure 23(f). We granted it, and this appeal followed. II. JURISDICTION AND STANDARDS OF REVIEW The District Court had jurisdiction under 28 U.S.C. § 1331. We have jurisdiction under 28 U.S.C. § 1292(e) and Federal Rule of Civil Procedure 23(f). We review the certification of a class for abuse of discretion, “which occurs if the district court’s decision rests upon a clearly erroneous finding of fact, an errant conclusion of law, or an improper application of law to fact.” In re Hydrogen Peroxide Antitrust Litig., 552 F.3d 305, 312 (3d Cir. 2008) (cleaned up). III. DISCUSSION GSK challenges the District Court’s holdings that the class is ascertainable and that common issues would predominate on causation. We asked the parties to brief a third, threshold issue: the scope of our review of a Rule 23(f) appeal. That is where we begin. A. We may limit the scope of our review under Rule 23(f). Rule 23(f) provides that a “court of appeals may permit an appeal from an order granting or denying class-action certification under this rule.” Fed. R. Civ. P. 23(f). The text does not expressly address whether a motions or merits panel may limit review to specific questions. No precedent of ours directly answers this question either. However, since Rule 23(f)’s inception, we have analogized it to another interlocutory appeal provision, 28 U.S.C. § 1292(b). Under that 15 subsection, we may choose which issues we review when we accept and decide an appeal. For this reason, we now hold we have the same discretion under Rule 23(f). Rule 23(f) models § 1292(b). Newton v. Merrill Lynch, Pierce, Fenner & Smith, Inc., 259 F.3d 154, 163 (3d Cir. 2001) (citing 7B Charles Alan Wright, Arthur R. Miller & Mary Kay Kane, Fed. Prac. & Proc. § 1802 (West Supp. 2000)). The statute authorizes us to permit an interlocutory appeal of a non- final order that “involves a controlling question of law as to which there is substantial ground for difference of opinion” where “an immediate appeal from the order may materially advance the ultimate termination of the litigation.” 28 U.S.C. § 1292(b). As the Supreme Court has explained, “[c]ourts of appeals wield ‘unfettered discretion’ under Rule 23(f), akin to the discretion afforded circuit courts under § 1292(b). But Rule 23(f) otherwise ‘departs from the § 1292(b) model,’ for it requires neither district court certification nor adherence to § 1292(b)’s other ‘limiting requirements.’” Microsoft Corp. v. Baker, 582 U.S. 23, 31 (2017) (quoting Comm. Note on Rule 23(f)). In short, Rule 23(f) is the class-action version of § 1292(b), save that it confers on courts of appeals even greater discretion. Under § 1292(b), we may choose which issues to review. The Supreme Court has taken care to use permissive rather than mandatory language in characterizing appellate courts’ power over the scope of our review in § 1292(b) appeals. Yamaha Motor Corp., U.S.A. v. Calhoun held that a court of appeals has appellate jurisdiction over the entire order certified for appeal because “it is the order that is appealable,” not the certified question. 516 U.S. 199, 205 (1996) (emphasis omitted) (quoting 9 J. Moore & B. Ward, Moore’s Federal 16 Practice ¶ 110.25[1], p. 300 (2d ed. 1995). The Court could have said a court of appeals must consider every question the parties raise. It did not. Instead, it consistently said that appeals courts may do that. See, e.g., id. at 205. We too have taken care to use permissive words like “may” and “can,” rather than mandatory language like “must” or “shall,” in the § 1292(b) context. See, e.g., Lundeen v. 10 W. Ferry St. Operations LLC, 156 F.4th 332, 337 (3d Cir. 2025) (“Although the District Court certified a single question, our review may reach any matter ‘fairly included within the certified order.’” (emphasis added) (quoting Barbato v. Greystone All., LLC, 916 F.3d 260, 264 (3d Cir. 2019))); Gruber v. Price Waterhouse, 911 F.2d 960, 963 (3d Cir. 1990) (“[S]ince we review orders and not isolated legal questions, we may consider all grounds that might require reversal of the order.” (emphasis added) (citation omitted)); see also McMunn v. Babcock & Wilcox Power Generation Grp., 869 F.3d 246, 266 (3d Cir. 2017) (noting “may” is permissive). This permissive language is no accident. It reflects the position we adopted around the same time we started writing on these discretionary terms: on a § 1292(b) appeal, “we are free to consider ‘all grounds advanced in support of [reversal] and all grounds suggested for [affirmance].’” See Miller v. Bolger, 802 F.2d 660, 666 (3d Cir. 1986) (quoting Struble v. N.J. Brewery Emps.’ Welfare Tr. Fund, 732 F.2d 325, 336 n.10 (3d Cir. 1984)). “In deciding whether to exercise that power, we are guided by prudential considerations”—not by any obligation to consider every challenge the appellant raises. Id. Were there any doubt, in 1988 our full Court adopted these expressly permissive terms for § 1292(b) appeals, 17 providing that we “may consider all grounds that might require reversal of the order appealed from.” In re Data Access Sys. Sec. Litig., 843 F.2d 1537, 1539 (3d Cir. 1988) (en banc) (emphasis added) (citing Merican, Inc. v. Caterpillar Tractor Co., 713 F.2d 958, 962 n.7 (3d Cir. 1983)), superseded on other grounds by statute as stated in In re Exxon Mobil Corp. Sec. Litig., 500 F.3d 189, 198 (3d Cir. 2007). We have refused to consider a ground for reversal on a § 1292(b) appeal at least three times: in Miller, 802 F.2d at 666–67; Resol. Tr. Corp. v. Cityfed Fin. Corp., 57 F.3d 1231, 1236 & n.6 (3d Cir. 1995), vacated on other grounds sub nom. Atherton v. FDIC, 519 U.S. 213 (1997); and most recently in this very case. A decade ago, we heard an appeal from the District Court’s denial of GSK’s motion to dismiss for failure to state a claim. See Avandia I, 804 F.3d at 637. GSK had moved to dismiss all of the Plans’ claims, federal and state. See id. at 636–37 & n.9. The District Court certified for appeal three questions about its denial of the motion to dismiss the federal-law claims. Id. at 637. Even though GSK asked us to reverse on the state-law claims as well, we refused to consider them. Id. at 637 n.11. The lesson of our § 1292(b) practice: we may circumscribe the scope of our review, refusing to consider asserted grounds for reversal. See 16 Charles Alan Wright, Arthur R. Miller & Edward H. Cooper, Fed. Prac. & Proc. § 3931.1 (3d. ed. 2026). To be sure, in the more distant past we declared that “[o]n a Section 1292(b) appeal we consider all grounds which might require a reversal of the order appealed from.” Murphy v. Heppenstall Co., 635 F.2d 233, 235 n.1 (3d Cir. 1980); see 18 also Merican, 713 F.2d at 962 n.7 (same); In re Sch. Asbestos Litig., 789 F.2d 996, 1002 & n.5 (3d Cir. 1986) (same). But these cases predate our 1988 en banc decision in Data Access. Since then, we have never repeated the arguably mandatory language. Instead, we have used the permissive version. See, e.g., Howard Hess Dental Lab’ys Inc. v. Dentsply Int’l, Inc., 424 F.3d 363, 368–69 (3d Cir. 2005) (“We may ‘consider all grounds which might require a reversal of the order appealed from.’” (emphasis added) (quoting Merican, 713 F.2d at 962 n.7)).6 There are two caveats. First, we cannot set aside challenges to our subject matter jurisdiction. See Fox v. Saginaw Cnty., 67 F.4th 284, 292 (6th Cir. 2023). Even if a motions panel purported to refuse review of a jurisdictional question, the merits panel not only may, but must, address it. Cf. Council Tree Commc’ns, Inc. v. FCC, 503 F.3d 284, 292 6 There is also some language in Katz v. Carte Blanche Corporation, 496 F.2d 747 (3d Cir. 1974) (en banc), cert. denied, 419 U.S. 885 (1974), that one could read as requiring us to consider any argument that a district court erroneously certified a class, see id. at 756. Even if that were the right reading of Katz, it would not survive our decision in Link v. Mercedes-Benz of North America, Inc., 550 F.2d 860 (3d Cir. 1977) (en banc). The case presented two questions: whether the District Court erred in certifying a class and whether it could bifurcate the trial and use separate juries for the liability phase and damages phase were liability found. Id. at 861–62. Even though a motions panel had granted permission to appeal these matters, id. at 862, the full Court declined to rule on either one, id. at 861, 864–65; see also Sperling v. Hoffman-La Roche Inc., 862 F.2d 439, 443–44 (3d Cir. 1988). 19 (3d Cir. 2007). Second, as the history we have recounted reveals, although a motions panel is free to specify the issues for the merits panel to review, the merits panel may refuse to answer them. See, e.g., Link v. Mercedes-Benz of North America, Inc., 550 F.2d 860, 861, 864–65 (3d Cir. 1977) (en banc). In sum, Rule 23(f) essentially mirrors § 1292(b). To the extent they differ, Rule 23(f) provides more discretion, not less. Under § 1292(b), we may limit the scope of our review of an order to select issues. We have exercised this discretion for decades. There is no reason to think we may not do the same on a Rule 23(f) appeal. Accordingly, we hold we may circumscribe review of a Rule 23(f) appeal to the issues we choose. B. The proposed class is ascertainable. Class certification is warranted when the putative class meets the requirements of Rule 23(a) and Rule 23(b)(1), (2), or (3). See Reyes v. Netdeposit, LLC, 802 F.3d 469, 482 (3d Cir. 2015). Here, there is no dispute the Plans satisfied Rule 23(a). What is disputed is whether they satisfy two requirements of Rule 23(b)(3): predominance and ascertainability. Although we do not believe the ascertainability issue presented in this case merits review, we briefly address it out of respect for the parties. To establish ascertainability, the plaintiffs must prove that “(1) the class is defined with reference to objective criteria” and “(2) there is a reliable and administratively feasible mechanism for determining whether putative class members fall within the class definition.” In re Niaspan 20 Antitrust Litig., 67 F.4th 118, 130 (3d Cir. 2023) (quoting Hargrove v. Sleepy’s LLC, 974 F.3d 467, 469–70 (3d Cir. 2020)). That happens when membership can be determined from a combination of objective records and verifiable affidavits from potential members. See Byrd v. Aaron’s Inc., 784 F.3d 154, 171 (3d Cir. 2015); Hargrove, 974 F.3d at 480; City Select Auto Sales Inc. v. BMW Bank of N. Am. Inc., 867 F.3d 434, 441 (3d Cir. 2017). The Plans intend to determine membership using this very combination of evidence: identifying potential members with Avandia purchase and reimbursement records, then confirming actual membership with an affidavit and proof of purchase. GSK nonetheless advances two arguments that the Plans failed to prove there is a reliable and feasible mechanism for identifying class members. First, it contends there are no records of which putative members reimbursed Avandia prescriptions in the class period. Second, it asserts that even if those records existed, they would not indicate whether a putative member was an end-payor (thus eligible for class membership) or was fully insured (hence ineligible for class membership). The District Court’s finding that there are objective records of the Plans’ reimbursements for Avandia prescriptions has no clear error. We note that two named plaintiffs—Allied Services Division Welfare Fund and United Benefit Fund (“UBF”)—dropped out of the case when they could not obtain purchase records from their pharmaceutical benefit managers (“PBMs”). But, after receiving a subpoena, UBF’s PBM provided the data, showing it has (or at least had) the records after all. Even if PBMs could not provide the requisite data, the District Court’s finding that class members would be able to 21 corroborate their claims was not clearly erroneous because a potential class member’s affidavit can be corroborated using multiple forms of documentation. The District Court’s finding the Plans will be able to distinguish end-payors from fully insured plans did not clearly err either. GSK claims that most TPPs will rely on PBM purchase records to establish their membership in the class. Generally, those documents do not identify whether a purchaser was an end-payor. See Niaspan, 67 F.4th at 136. The Plans, however, do not propose to rely on PBM data alone; the record contained ample evidence they would be able to use other resources to distinguish end-payors from fully insured TPPs. In a final bid to prevent class certification, GSK frames the Plans’ proposal as a dilemma. In its view, the proposal permits potential class members to identify themselves— violating our admonition that ascertainability cannot rest on mere say-so—or it depends on individualized evidence, risking the very mini-trials the ascertainability requirement exists to prevent. See id. at 130–31. This dilemma is illusory. The Plans’ proposal for distinguishing end-payors from fully insured plans does not rely on mere say-so. Each potential class member’s payor status would be verified with documentation like receipts, claims data, plan documents, or public records. And using these records to confirm a TPP is an end-payor hardly constitutes a mini-trial. To the contrary, it is the “straightforward ‘yes-or-no’ review of existing records to identify class members” we have held “is administratively feasible even if it requires review of individual records with 22 cross-referencing of voluminous data from multiple sources.” Kelly v. RealPage Inc., 47 F.4th 202, 224 (3d Cir. 2022). The Plans’ proposal falls well within the bounds of our precedents, leaving no abuse of discretion in holding the class is ascertainable. C. The record so far does not show that common issues would predominate. Rule 23(b)(3) requires “questions of law or fact common to class members predominate over any questions affecting only individual members.” Reyes, 802 F.3d at 482 (quoting Fed. R. Civ. P. 23(b)(3)). “An individual question is one where ‘members of a proposed class will need to present evidence that varies from member to member,’ while a common question is one where ‘the same evidence will suffice for each member to make a prima facie showing [or] the issue is susceptible to generalized, class-wide proof.’” Tyson Foods, Inc. v. Bouaphakeo, 577 U.S. 442, 453 (2016) (alteration in original) (quoting 2 W. Rubenstein, Newberg on Class Actions § 4:50 196–97 (5th ed. 2012)). “[T]he presence of individual questions does not per se rule out a finding of predominance.” In re Prudential Ins. Co. Am. Sales Prac. Litig. Agent Actions, 148 F.3d 283, 315 (3d Cir. 1998). Common questions predominate so long as they “overwhelm individual issues.” Neale v. Volvo Cars of N. Am., LLC, 794 F.3d 353, 371 (3d Cir. 2015) (citing Amgen Inc. v. Conn. Ret. Plans & Tr. Funds, 568 U.S. 455, 468–69 (2013)). In other words, “[w]hen one or more of the central issues in the action are common to the class and can be said to predominate, the action may be considered proper under Rule 23(b)(3) even 23 though other important matters will have to be tried separately, such as damages or some affirmative defenses peculiar to some individual class members.” Tyson, 577 U.S. at 453–54 (cleaned up). “Class certification is proper only ‘if the trial court is satisfied, after a rigorous analysis, that the prerequisites’ of Rule 23 are met.” Hydrogen Peroxide, 552 F.3d at 309 (quoting Gen. Tel. Co. of Sw. v. Falcon, 457 U.S. 147, 161 (1982)). “Factual determinations necessary to make Rule 23 findings must be made by a preponderance of the evidence.” Id. at 320. This requires resolving “every dispute that is relevant to class certification” before it can be granted. Ferreras v. Am. Airlines, 946 F.3d 178, 183 (3d Cir. 2019). We “analyze predominance in the context of Plaintiffs’ actual claims” because “the nature of the evidence that will suffice to resolve a question determines whether the question is common or individual.” Neale, 794 F.3d at 371–72 (quoting, in second passage, Hydrogen Peroxide, 552 F.3d at 311). That means class-wide evidence of each element of the cause of action must predominate over evidence particular to individual class members. See Reyes, 802 F.3d at 482–83, 489; see also Hydrogen Peroxide, 552 F.3d at 311 (“If proof of the essential elements of the cause of action requires individual treatment, then class certification is unsuitable.” (cleaned up)). Accordingly, here predominance is “satisfied if each element of the alleged RICO violation involves common questions of law and fact capable of proof by evidence common to the class.” Reyes, 802 F.3d at 489 (emphasis omitted). “Establishing liability under [§ 1962(c)] of the RICO statute requires (1) conduct (2) of an enterprise (3) through a 24 pattern (4) of racketeering activity, plus an injury to business or property.” Id. (alteration in original) (quoting In re Ins. Brokerage Antitrust Litig., 579 F.3d 241, 269 (3d Cir. 2009)). Implicit is a requirement that the racketeering activity was the but-for cause of the alleged injury. Id. “The simplest statement of the concept of but-for causation is that event A is a but-for cause of event B if event B could not happen without event A happening first.” Mosley, 454 F.3d at 266. “Although reliance on the defendant’s alleged misrepresentation is not an element of a RICO mail-fraud claim, the plaintiffs’ theory of injury in most RICO mail-fraud cases will nevertheless depend on establishing that someone— whether the plaintiffs themselves or third parties—relied on the defendant’s misrepresentation.” Sergeants Benevolent Ass’n Health & Welfare Fund v. Sanofi-Aventis U.S. LLP, 806 F.3d 71, 87 (2d Cir. 2015) cert. denied, 580 U.S. 825 (2016). That is because reliance will typically be a necessary step in the causal chain linking the defendant’s alleged misrepresentation to the plaintiffs’ injury: if the person who was allegedly deceived by the misrepresentation (plaintiff or not) would have acted in the same way regardless of the misrepresentation, then the misrepresentation cannot be a but-for, much less proximate, cause of the plaintiffs’ injury. Id. Because “reliance is nearly always an individualized question,” Harnish v. Widener Univ. Sch. of L., 833 F.3d 298, 309 (3d Cir. 2016), establishing predominance on causation in 25 a putat