POOLER, Circuit Judge:

We turn to this case for the third time, as the Supreme Court released its latest views on class arbitration waivers in AT & T Mobility LLC v. Concepcion, ___ U.S. ___, 131 S.Ct. 1740, 179 L.Ed.2d 742 (2011), just weeks after we issued our decision in In re American Express Merchants' Litigation, 634 F.3d 187 (2d Cir. 2011) ("Amex II"). Amex II returned to us from the Supreme Court, after defendants American Express Company and American Express Travel Related Services Co. (together, "Amex") sought review from the Supreme Court following our decision in In re American Express Merchants' Litigation, 554 F.3d 300 (2d Cir.2009) ("Amex I"). In Amex I, we considered the enforcement of a mandatory arbitration clause in a commercial contract also containing a "class action waiver," that is, a provision which forbids the parties to the contract from pursuing anything other than individual claims in the arbitral forum. We found the class action waiver unenforceable, "because enforcement of the clause would effectively preclude any action seeking to vindicate the statutory rights asserted by the plaintiffs." Amex I, 554 F.3d at 304.

The Supreme Court granted Amex's petition for a writ for certiorari, then vacated and remanded for reconsideration in light of its decision in Stolt-Nielsen S.A. v. AnimalFeeds Int'l Corp., ___ U.S. ___, 130 S.Ct. 1758, 176 L.Ed.2d 605 (2010). Finding our original analysis unaffected by Stolt-Nielsen, we again reversed the district court's decision and remanded for further proceedings. Amex II, 634 F.3d at 199-200. On April 11, 2011, we placed a hold on the mandate in Amex II in order for Amex to file a petition seeking a writ of certiorari. While the mandate was on hold, the Supreme Court issued its decision in AT & T Mobility LLC v. Concepcion, ___ U.S. ___, 131 S.Ct. 1740, 179 L.Ed.2d 742 (2011). The Concepcion Court held that the Federal Arbitration Act preempted a California law barring the enforcement of class action waivers in consumer contracts. Id. at 1750-51. The parties submitted supplemental briefing discussing the impact, if any, of Concepcion on our previous decisions, and we find oral argument unnecessary. As discussed below, Concepcion does not alter our analysis, and we again reverse the district court's decision and remand for further proceedings.

BACKGROUND

Because the only issue before us is the narrow question of whether the class action waiver provision contained in the contract between the parties should be enforced, we provide but a brief recitation of the facts.

A. Procedural Posture.

The plaintiffs appealed from the March 20, 2006 judgment of the United States District Court for the Southern District of New York, which granted Amex's motion to compel arbitration pursuant to the Federal Arbitration Act ("FAA") and Federal Rule of Civil Procedure 12(b). See In re Am. Express Merchs. Litig., No. 03 CV 9592, 2006 WL 662341 (S.D.N.Y. Mar. 16, 2006) (Daniels, J.).

B. The Parties.

The amended complaint alleges that Amex "is the leading issuer of general purpose and corporate charge cards to consumers and businesses in the United States and throughout the world. It is also the leading provider of charge card services to merchants." The named plaintiffs are: (1) California and New York corporations which operate businesses which have contracted with Amex and (2) the National Supermarkets Association, Inc. ("NSA"), "a voluntary membership-based trade association that represents the interests of independently owned supermarkets."

The named plaintiffs seek to represent the following class:

C. The Plaintiffs' Substantive Claims.

The plaintiffs' dispute with Amex rests upon the distinction between "charge cards" and "credit cards."3 The district court explained the distinction:

In re Am. Express Merchs., 2006 WL 662341, at *1, n. 6.

According to the plaintiffs, Amex had until recent years centered its business on the issuance of corporate and personal charge cards to corporate clients and affluent consumers. The plaintiffs further assert that "[h]olders of charge cards are more affluent than credit cardholders, and a vastly higher percentage of charge cards than credit cards are held by businesses and used for business travel and other corporate purposes." In fact, the plaintiffs allege that Amex itself contends that "the average purchase on an American Express card is 17% higher than the average purchase made on a credit card." Thus, the holder of a charge card is likely to be "a higher class of customer" and, as such, is particularly attractive to merchants such as the plaintiffs.

As a result of this distinction, Amex has traditionally been able to charge high "merchant discount fees," which are the fees a card issuer withholds as a percentage of each purchase made with its card at the merchant's establishment. These fees, the plaintiffs aver, "are at least 35% higher than competitive rates" applicable to mass-market credit cards such as Visa, MasterCard, and Discover. Over the last decade, the plaintiffs allege, Amex's "business in the markets for credit card issuance and credit card services has grown dramatically." By leveraging its market power in corporate and personal charge cards, however, plaintiffs allege that American Express was able to compel merchants to accept "its new revolving credit card product[s] at the same elevated discount rate, which vastly exceeded the rate for comparable Visa, MasterCard or Discover products."

According to the plaintiffs, the vehicle of this compulsion is the "Honor All Cards" provision contained in the Card Acceptance Agreement. Under the Agreement, a merchant does not contract to accept any one Amex product as a form of payment. Rather, the Agreement applies:

The plaintiffs assert that, by means of the "Honor All Cards" provision, merchants are faced with the choice of paying supracompetitive merchant discount fees (i.e., fees above competitive levels) on Amex's new mass-market products or "inevitably los[ing] a significant portion of the sales they receive from businesses, travelers, affluent consumers, and others" who are the traditional users of Amex charge cards. This, the plaintiffs claim, amounts to an illegal "tying arrangement," in violation of Section 1 of the Sherman Act, 15 U.S.C. § 1.4

D. The Card Acceptance Agreement.

The basic contractual relationship between Amex and the plaintiffs was set forth in an affidavit of an Amex executive:

The Card Acceptance Agreement is a standard form contract issued by Amex. It may be terminated by either party "at any time by sending written notice to the other party." Further, Amex reserves the right:

According to Amex, the Card Acceptance Agreement has "expressly permitted amendments upon notice" for more than twenty-five years. The Card Acceptance Agreement also contains a choice of law provision designating New York law as governing and, as Amex states, there is no dispute that the agreement "has always" contained this provision.

By contrast, it is only since 1999 that the Card Acceptance Agreement has contained a mandatory arbitration clause:

At the heart of the instant appeal is the following provision contained in the Agreement:

(emphasis in the original). The Card Acceptance Agreement thus not only precludes a merchant from bringing a class action lawsuit, it also precludes the signatory from having any claim arbitrated on anything other than an individual basis.

E. The District Court's Decision.

Amex moved to compel arbitration pursuant to the terms of the Card Acceptance Agreement. In its March 16, 2006 opinion, the district court granted Amex's motion, first holding that the arbitration clause in the Agreement was "a paradigmatically broad clause" which was certainly applicable to the dispute between the parties. In re Am. Express Merchs. Litig., 2006 WL 662341, at *4. The district court also held that "[t]he enforceability of the collective action waivers is a claim for the arbitrator to resolve. Issues relating to the enforceability of the contract and its specific provisions are for the arbitrator, once arbitrability is established." Id. at *6. Thus, the district court concluded that all of the plaintiffs' substantive antitrust claims, as well the question of whether or not the class action waivers were enforceable, were subject to arbitration. Having so decided, the district court dismissed plaintiffs' cases against Amex. Id. at *10.

E. Our Original Decision, Amex I.

The plaintiffs filed a timely appeal. We first decided that the issue of the class action waiver's enforceability was a matter for the court, not the arbitrator. Amex I, 554 F.3d at 310. Neither party takes issue with that holding, which we find survives Stolt-Nielsen and Concepion.

Turning to the question of whether the class action waiver in the Card Acceptance Agreement was enforceable, we found that Green Tree Financial Corp.-Alabama v. Randolph, 531 U.S. 79, 121 S.Ct. 513, 148 L.Ed.2d 373 (2000), controlled our analysis:

Amex I, 554 F.3d at 315-16. Based in part on plaintiffs' submission of an affidavit from an economist detailing the fiscal impracticality of pursuing individual claims, we concluded that:

Id. at 319. Thus, we held that:

Id. at 320. Amex timely filed a petition for a writ of certiorari. Am. Express Co. v. Italian Colors Rest., ___ U.S. ___, 130 S.Ct. 2401, 176 L.Ed.2d 920 (2010). The Supreme Court granted Amex's petition, vacated our original decision, and remanded for further consideration in light of its holding in Stolt-Nielsen.

G. The Stolt-Nielsen Decision.

In Stolt-Nielsen, petitioners were shipping companies. See 130 S.Ct. at 1764. The charter party—a maritime contract governing the relationship between the parties—provided, in relevant part

Id. at 1765. Respondent AnimalFeeds, along with other charterers, sued Stolt-Nielsen, alleging price fixing, and eventually served a demand for class arbitration. Id. The parties agreed to have an arbitration panel decide the threshold issue of whether the charter party permitted class arbitration, and stipulated before the panel that the arbitration clause was silent on the issue of class arbitration. Id. at 1765-66. The panel concluded that the expert testimony offered did not demonstrate an "inten[t] to preclude class arbitration." Id. (alteration in original). After finding that the issue was controlled by the Supreme Court's decision in Green Tree Fin. Corp. v. Bazzle, 539 U.S. 444, 123 S.Ct. 2402, 156 L.Ed.2d 414, (2003), the panel concluded Bazzle and policy considerations dictated finding the clause permitted class arbitration. Id.

The Supreme Court found that the arbitration panel "imposed its own policy choice," rather than "identifying and applying a rule of decision derived from the FAA or either maritime or New York law," and "thus exceeded its powers." 130 S.Ct. at 1770. Tackling the issue itself, the Court found the FAA controlling, id. at 1773, and reaffirmed that "arbitration is simply a matter of contract between the parties." Id. at 1774 (alterations omitted). The Court concluded that "a party may not be compelled under the FAA to submit to class arbitration unless there is a contractual basis for concluding that the party agreed to do so." Id. at 1775 (emphasis in the original).

H. Our Decision in Amex II.

On remand from the Supreme Court, we found Stolt-Nielsen did not require us to depart from our original analysis. The key issue, we concluded, was whether the mandatory class action waiver in the Card Acceptance Agreement is enforceable even if the plaintiffs are able to demonstrate that the practical effect of enforcement of the waiver would be to preclude their bringing Sherman Act claims against Amex. In re American Express Merchants' Litigation, 634 F.3d 187, 196 (2d Cir.2011). We concluded enforcement of the class action waiver would indeed bar plaintiffs from pursuing their statutory claims because the "record evidence before us establishe[d], as a matter of law, that the cost of plaintiffs' individually arbitrating their dispute with Amex would be prohibitive, effectively depriving plaintiffs of the statutory protections of the antitrust laws." Id. at 197-98.

We relied on detailed testimony from Gary L. French, Ph.D., an economist associated with Nathan Associates Inc., a financial consulting firm retained by the plaintiffs. Dr. French submitted a detailed affidavit to the district court, in which he opined, inter alia, that "[i]n my experience, even a relatively small economic antitrust study will cost at least several hundred thousand dollars, while a larger study can easily exceed $1 million after reviewing the complaint and doing some preliminary research in this case, it is my opinion that ... the cost for this case will fall in the middle of the range...." (Joint Appendix at p. 362-63, ¶ 4). Dr. French then opined that it was not economically rational to pursue an individual action against Amex in light of these substantial expert witness costs. (Joint Appendix at p. 365, ¶ 10-11). Amex II, 634 F.3d at 198. We found that "Dr. French's affidavit demonstrates that the only economically feasible means for enforcing their statutory rights is via a class action," and remanded the case to the district court. Id.

ANALYSIS

Shortly after we issued our opinion in Amex II, the Supreme Court handed down its opinion in Concepcion, 131 S.Ct. at 1740. In Concepcion, the Supreme Court held that the FAA preempted California common law deeming most class-action arbitration waivers in consumer contracts unconscionable. Id. at 1746. Amex argues that Concepcion applies a fortiori here, requiring reversal of our holding in Amex II. It is tempting to give both Concepcion and Stolt-Nielsen such a facile reading, and find that the cases render class action arbitration waivers per se enforceable. But a careful reading of the cases demonstrates that neither one addresses the issue presented here: whether a class-action arbitration waiver clause is enforceable even if the plaintiffs are able to demonstrate that the practical effect of enforcement would be to preclude their ability to vindicate their federal statutory rights.

The specific preemption question addressed by the Supreme Court in Concepcion was "whether the FAA prohibits States from conditioning the enforceability of certain arbitration agreements on the availability of classwide arbitration procedures." Id. at 1744. Under California's common law, class action waivers contained in arbitration clauses were regularly found unconscionable, especially in consumer contracts. Id. at 1746. The Supreme Court began its analysis by reaffirming the "liberal federal policy favoring arbitration agreements, notwithstanding any state substantive or procedural policies to the contrary." Id. at 1749 (internal quotation marks). By requiring the "availability of classwide arbitration," the Court held, the California rule "interfere[d] with fundamental attributes of arbitration and thus create[d] a scheme inconsistent with the FAA." Id. at 1748. In response to the dissent's discussion of the benefits of class-arbitration as a means of addressing multiple small claims, the majority concluded that "[s]tates cannot require a procedure that is inconsistent with the FAA, even if it is desirable for unrelated reasons." Id. at 1753.

Concepcion plainly offers a path for analyzing whether a state contract law is preempted by the FAA. Here, however, our holding rests squarely on "a vindication of statutory rights analysis, which is part of the federal substantive law of arbitrability." Amex I, 554 F.3d at 320; see also Kristian v. Comcast Corp., 446 F.3d 25, 47-48 (1st Cir.2006) (severing as unenforceable provision of arbitration agreement limiting availability of treble damages under antitrust statute); Hadnot v. Bay, Ltd., 344 F.3d 474, 478 n. 14 (5th Cir.2003) (severing restriction on available remedies from arbitration agreement after finding that "ban on punitive and exemplary damages is unenforceable in a Title VII case"); Paladino v. Avnet Computer Techs., Inc., 134 F.3d 1054, 1062 (11th Cir.1998) (holding that "[w]hen an arbitration clause has provisions that defeat the remedial purpose of the statute ... the arbitration clause is not enforceable" and language insulating employer from damages and equitable relief rendered clause unenforceable).

Concepcion and Stolt-Nielsen, taken together, stand squarely for the principle that parties cannot be forced to arbitrate disputes in a class-action arbitration unless the parties agree to class action arbitration. Concepcion, 131 S.Ct. at 1750-51 ("class arbitration, to the extent it is manufactured by [state law] rather than consensual, is inconsistent with the FAA")5; Stolt-Nielsen, 130 S.Ct. at 1775 ("a party may not be compelled under the FAA to submit to class arbitration unless there is a contractual basis for concluding that the party agreed to do so."). We plainly acknowledged in Amex II that we could not, and thus were not, ordering the parties to participate in class arbitration. 634 F.3d at 200 ("Stolt-Nielsen plainly precludes us from ordering class-wide arbitration.").

What Stolt-Nielsen and Concepcion do not do is require that all class-action waivers be deemed per se enforceable. That leaves open the question presented on this appeal: whether a mandatory class action waiver clause is enforceable even if the plaintiffs are able to demonstrate that the practical effect of enforcement would be to preclude their ability to bring federal antitrust claims. While we cannot rely on Concepcion or Stolt-Nielsen to answer the question before us, we continue to find useful guidance in other Supreme Court decisions addressing the issue of vindicating federal statutory rights via arbitration.

We begin our analysis with the well-settled rule that class action lawsuits are suitable as a vehicle for vindicating statutory rights. Supreme Court precedent recognizes that the class action device is the only economically rational alternative when a large group of individuals or entities has suffered an alleged wrong, but the damages due to any single individual or entity are too small to justify bringing an individual action. The Court made the point forcefully more than thirty years ago in the context of an antitrust action:

Eisen v. Carlisle & Jacquelin, 417 U.S. 156, 161, 94 S.Ct. 2140, 40 L.Ed.2d 732 (1974). As the Court later opined, "`[t]he policy at the very core of the class action mechanism is to overcome the problem that small recoveries do not provide the incentive for any individual to bring a solo action prosecuting his or her rights.'" Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 617, 117 S.Ct. 2231, 138 L.Ed.2d 689 (1997) (quoting Mace v. Van Ru Credit Corp., 109 F.3d 338, 344 (7th Cir.1997)); see also Deposit Guar. Nat'l Bank v. Roper, 445 U.S. 326, 338, 100 S.Ct. 1166, 63 L.Ed.2d 427 (1980) ("[A class action] may motivate [plaintiffs] to bring cases that for economic reasons might not be brought otherwise ... [, thereby] vindicating the rights of individuals who otherwise might not consider it worth the candle to embark on litigation in which the optimum result might be more than consumed by the cost.") (footnote omitted); Carnegie v. Household Int'l, Inc., 376 F.3d 656, 661 (7th Cir.2004) ("[T]he realistic alternative to a class action is not 17 million individual suits, but zero individual suits, as only a lunatic or a fanatic sues for $30." (emphasis omitted)).

Arbitration is also recognized as an effective vehicle for vindicating statutory rights, but only "so long as the prospective litigant may effectively vindicate its statutory cause of action in the arbitral forum." Mitsubishi Motors Corp. v. Soler Chrysler-Plymouth, Inc., 473 U.S. 614, 632, 105 S.Ct. 3346, 87 L.Ed.2d 444 (1985) (emphasis added). Indeed, in dicta the Mitsubishi Court noted that should clauses in a contract operate "as a prospective waiver of a party's right to pursue statutory remedies for antitrust violations, we would have little hesitation in condemning the agreement as against public policy." Id. at 637, n. 19, 105 S.Ct. 3346. As we observed in Amex II:

634 F.3d at 197.

Applying its rule regarding the arbitrability of federal statutory claims from Mitsubishi, in Gilmer v. Interstate/Johnson Lane Corp., 500 U.S. 20, 111 S.Ct. 1647, 114 L.Ed.2d 26 (1991), the Supreme Court permitted the arbitration, rather than litigation, of a plaintiff's Age Discrimination in Employment Act claim. Id. at 28, 111 S.Ct. 1647 (quoting Mitsubishi Motors, 473 U.S. at 637, 105 S.Ct. 3346). In Gilmer, the Court concluded that the plaintiff in that case could effectively vindicate his asserted rights in the arbitral forum. The plaintiff, a manager at a brokerage firm, asserted that he had been terminated by the firm in violation of the ADEA. Id. at 23, 111 S.Ct. 1647. After the plaintiff filed suit in federal district court, the defendant firm moved to compel arbitration pursuant to a mandatory arbitration provision contained in the rule of the New York Stock Exchange ("NYSE"), to which the plaintiff had agreed to be bound when he became a registered securities representative. Id. at 23-24, 111 S.Ct. 1647. The Gilmer Court held that because "[i]t is by now clear that statutory claims may be the subject of an arbitration agreement," the arbitration clause was enforceable "unless Congress itself has evinced an intention to preclude a waiver of judicial remedies for the statutory rights at issue." Id. at 26, 111 S.Ct. 1647 (quoting Mitsubishi, 473 U.S. at 628, 105 S.Ct. 3346).

The Court rejected plaintiff's contention that "arbitration procedures cannot further the purposes of the ADEA because they do not provide for broad equitable relief and class actions." Id. at 32, 111 S.Ct. 1647. Rather, the Court found that:

Id. (citations, internal quotation marks, and brackets omitted).6

Gilmer's conclusion that where the plaintiff's statutory rights could effectively be vindicated through arbitration does not affect the case before us, because here plaintiffs have demonstrated that their statutory rights cannot be vindicated through individual arbitrations. Nearly a decade after Gilmer, in Green Tree Financial Corp.-Alabama v. Randolph, the Supreme Court acknowledged in dicta "that the existence of large arbitration costs could preclude a litigant ... from effectively vindicating her federal statutory rights in the arbitral forum." 531 U.S. 79, 90, 121 S.Ct. 513, 148 L.Ed.2d 373 (2000). Among the costs at issue were "payment of filing fees, arbitrators' costs, and other arbitration expenses." Id. at 84, 121 S.Ct. 513. In the end, the Green Tree Court found plaintiff failed to submit sufficient evidence to demonstrate the costs of arbitration would effectively prohibit her from vindicating her statutory rights, dooming her attempt to have the arbitration clause declared unenforceable:

Id. at 91-92, 121 S.Ct. 513.

As the Tenth Circuit explained:

Shankle v. B-G Maint. Mgmt. of Colo., Inc., 163 F.3d 1230, 1234 (10th Cir.1999) (citations omitted); see also Paladino v. Avnet Computer Techs., Inc., 134 F.3d 1054, 1060 (11th Cir.1998) (holding that arbitration agreement which proscribed award of Title VII damages was unenforceable because it was fundamentally at odds with the purposes of Title VII); Cole v. Burns Int'l Sec. Servs., 105 F.3d 1465, 1468 (D.C.Cir.1997) ("We do not read Gilmer as mandating enforcement of all mandatory agreements to arbitrate statutory claims; rather we read Gilmer as requiring the enforcement of arbitration agreements that do not undermine the relevant statutory scheme.")

Neither Stolt-Nielsen nor Concepcion overrules Mitsubishi, and neither makes mention of Green Tree. We continue to find Green Tree "controlling here to the extent that it holds that when `a party seeks to invalidate an arbitration agreement on the ground that arbitration would be prohibitively expensive, that party bears the burden of showing the likelihood of incurring such costs.'" Amex II, 634 F.3d at 197 (quoting Green Tree, 531 U.S. at 92, 121 S.Ct. 513). Other Circuits permit plaintiffs to challenge class-action waivers on the grounds that prosecuting such claims on an individual basis would be a cost prohibitive method of enforcing a statutory right. See, e.g., In re Cotton Yarn Antitrust Litig., 505 F.3d 274, 285 (4th Cir.2007) ("[I]f a party could demonstrate that the prohibition on class actions likely would make arbitration prohibitively expensive, such a showing could invalidate an agreement.") (citation omitted); Livingston v. Assocs. Fin., Inc., 339 F.3d 553, 557 (7th Cir.2003) ("In the present case, the [plaintiffs] have not offered any specific evidence of arbitration costs that they may face in this litigation, prohibitive or otherwise, and have failed to provide any evidence of their inability to pay such costs...."); Adkins v. Labor Ready, Inc., 303 F.3d 496, 503 (4th Cir.2002) ("[Lead plaintiff] makes no showing of the specific financial status of any of the plaintiffs at the time this action was brought. He provides no basis for a serious estimation of how much money is at stake for each individual plaintiff."). In each of these cases, plaintiffs' attempts to avoid the waiver clause failed because plaintiffs were unable to demonstrate the class-action waivers barred them from vindicating their statutory rights. Their failures speak to the quality of the evidence presented, not the viability of the legal theory. The fact that plaintiffs so often fail in their attempts to overturn such waivers demonstrates that the evidentiary record necessary to avoid a class-action arbitration waiver is not easily assembled, and that the courts are capable of the scrutiny such arguments require.

Thus, we continue to find Green Tree "controlling here to the extent that it holds that when `a party seeks to invalidate an arbitration agreement on the ground that arbitration would be prohibitively expensive, that party bears the burden of showing the likelihood of incurring such costs.'" Amex I, 554 F.3d at 315 (quoting Green Tree, 531 U.S. at 92, 121 S.Ct. 513). Since there is no indication in Stolt-Nielsen or Concepcion that the Supreme Court intended to overturn either Green Tree or Mitsubishi, both cases retain their binding authority. Rodriguez de Quijas v. Shearson/Am. Express, Inc., 490 U.S. 477, 484, 109 S.Ct. 1917, 104 L.Ed.2d 526 (1989) ("If a precedent of this Court has direct application in a case, yet appears to rest on reasons rejected in some other line of decisions, the Court of Appeals should follow the case which directly controls, leaving to this Court the prerogative of overruling its own decisions.").

The evidence presented by plaintiffs here establishes, as a matter of law, that the cost of plaintiffs' individually arbitrating their dispute with Amex would be prohibitive, effectively depriving plaintiffs of the statutory protections of the antitrust laws. Dr. French stated that the purpose of his affidavit was "to provide an expert opinion concerning the likely costs and complexity of an expert economic study concerning the liability and damages" relating to this action, and to "provide my opinion as to whether it would be economically rational for such a merchant to pursue recovery of damages given the likely out-of-pocket costs of the arbitration or litigation proceeding." (Joint Appendix, at p. 362, ¶ 4)

Dr. French continued:

(Joint Appendix at p. 362-63, ¶ 4) Dr. French then considered the economic rationality of bringing an individual action against Amex in light of these substantial expert witness costs:

(Joint Appendix at p. 365, ¶ 10-11)

Dr. French's affidavit demonstrates that the only economically feasible means for plaintiffs enforcing their statutory rights is via a class action. As discussed in our earlier opinion, the district court did not directly address Dr. French's affidavit, focusing instead on the damages provision of the Clayton Act, 15 U.S.C. § 15(a). See Amex I, 554 F.3d at 317. We found that while the Clayton Act does provide for treble awards along with the recovery of attorneys' fees and expenses, that was unlikely to assist plaintiffs where, as here, "the trebling of a small individual damages award is not going to pay for the expert fees Dr. French has estimated will be necessary to make an individual plaintiff's case." Id. We also found the Clayton Act's fee-shifting provisions inadequate to alleviate our concerns given the low expert witness reimbursement rate. Id. at 318. "Even with respect to reasonable attorney's fees, which are shifted under Section 4 of the Clayton Act, the plaintiffs must include the risk of losing, and thereby not recovering any fees, in their evaluation of their suit's potential costs." Id.

We again find "Amex has brought no serious challenge to the plaintiffs' demonstration that their claims cannot reasonably be pursued as individual actions, whether in federal court or in arbitration." Amex I, 554 F.3d at 319. The "enforcement of the class action waiver in the Card Acceptance Agreement `flatly ensures that no small merchant may challenge American Express[s] tying arrangements under the federal antitrust laws.'" Id. Eradicating the private enforcement component from our antitrust law scheme cannot be what Congress intended when it included strong private enforcement mechanisms and incentives in the antitrust statutes. See Reiter v. Sonotone Corp., 442 U.S. 330, 344, 99 S.Ct. 2326, 60 L.Ed.2d 931 (1979) ("[P]rivate suits provide a significant supplement to the limited resources available to the Department of Justice for enforcing the antitrust laws and deterring violations."); see also Dando B. Cellini, An Overview of Antitrust Class Actions, 49 Antitrust L.J. 1501, 1506 (1980) (discussing private, class action antitrust lawsuits and observing that "it is obvious from the experience over the last fifteen years since the 1966 amendments to Rule 23 were adopted that linking an antitrust claim with a class action allegation can be devastatingly effective.").

Thus, as the class action waiver in this case precludes plaintiffs from enforcing their statutory rights, we find the arbitration provision unenforceable. We again emphasize our holding comes with caveats. See Amex I, 554 F.3d at 320 ("We emphasize two important limitations upon our holding.") Our decision in no way relies upon the status of plaintiffs as "small" merchants. We rely instead on the need for plaintiffs to have the opportunity to vindicate their statutory rights. See, e.g., Raniere v. Citigroup, Inc., ___ F.Supp.2d ___, ___, No. 11 Civ. 2248, 2011 WL 5881926, at *13 (S.D.N.Y. Nov. 22, 2011) ("even if AT & T is read broadly to acquiesce to the enforcement of an arbitral agreement that as a practical matter would prevent the vindication of state rights in the name of furthering the strong federal policy favoring arbitration, that would not alter the validity of the federal statutory rights analysis articulated in Mitsubishi, Green Tree [and] American Express"); Chen-Oster v. Goldman, Sachs & Co., No. 10 CIV 6950, 2011 WL 2671813, at *2-5 (S.D.N.Y. July 7, 2011) (declining to apply Concepcion where the question before the court involved the plaintiff's ability to vindicate a federal statutory right); Sutherland v. Ernst & Young, LLP, 768 F.Supp.2d 547, 550-51 (S.D.N.Y.2011) (finding Amex I "retains its persuasive force" following Stolt-Nielsen).

We do not hold today that class action waivers in arbitration agreements are per se unenforceable, or even that they are per se unenforceable in the context of antitrust actions. Rather, as demonstrated by the different outcomes in our sister Circuits, we hold that each waiver must be considered on its own merits, based on its own record, and governed with a healthy regard for the fact that the FAA "is a congressional declaration of a liberal federal policy favoring arbitration agreements." Moses H. Cone Mem'l Hosp., 460 U.S. at 24, 103 S.Ct. 927.

Our earlier opinion refrained from ordering the parties to submit to class arbitration, instead permitting Amex the choice between arbitration and litigation. Amex I, 554 F.3d at 321. Stolt-Nielsen plainly precludes any court from compelling the parties to submit to class-wide arbitration where the arbitration clause is silent as to class-wide arbitration. 130 S.Ct. at 1775 (a party does not agree "to submit to class arbitration unless there is a contractual basis for concluding that a party agreed to do so").

Which leads to the issue of how to proceed from here. As detailed above, we are persuaded by the record before us that if plaintiffs cannot pursue their allegations of antitrust law violations as a class, it is financially impossible for the plaintiffs to seek to vindicate their federal statutory rights. Since the plaintiffs cannot pursue these claims as class arbitration, either they can pursue them as judicial class action or not at all. If they are not permitted to proceed in a judicial class action, then, they will have been effectively deprived of the protection of the federal antitrust-law. The defendant will thus have immunized itself against all such antitrust liability by the expedient of including in its contracts of adhesion an arbitration clause that does not permit class arbitration, irrespective of whether or not the provision explicitly prohibits class arbitration.

Therefore, in light of the fact that the arbitration provision at issue here does not allow for class arbitration, under Stolt-Nielsen and by its terms, if the provision were enforced it would strip the plaintiffs of rights accorded them by statute. We conclude that this arbitration clause is unenforceable. We remand to the district court with the instruction to deny the defendant's motion to compel arbitration.

CONCLUSION

For the reasons given above, the decision of the district court is reversed. We remand to the district court for further proceedings consistent with this opinion.