(Slip Opinion) OCTOBER TERM, 2013 1 

Syllabus 

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is

being done in connection with this case, at the time the opinion is issued.

The syllabus constitutes no part of the opinion of the Court but has been

prepared by the Reporter of Decisions for the convenience of the reader. 

See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. 

SUPREME COURT OF THE UNITED STATES 

Syllabus 

MISSISSIPPI EX REL. HOOD, ATTORNEY GENERAL v. 

AU OPTRONICS CORP. ET AL. 

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR 

THE FIFTH CIRCUIT 

No. 12–1036. Argued November 6, 2013—Decided January 14, 2014 

Congress enacted the Class Action Fairness Act of 2005 (CAFA) to lower diversity jurisdiction requirements in class actions and, as relevant here, in mass actions, i.e., civil actions “in which monetary relief

claims of 100 or more persons are proposed to be tried jointly on the

ground that the plaintiffs’ claims involve common questions of law or 

fact,” 28 U. S. C. §1332(d)(11)(B)(i). Petitioner Mississippi sued respondent liquid crystal display (LCD) manufacturers in state court,

alleging violations of state law and seeking, inter alia, restitution for 

LCD purchases made by itself and its citizens. Respondents sought 

to remove the case to federal court. The District Court held that the 

suit qualified as a mass action under §1332(d)(11)(B)(i), but remanded the suit to state court on the ground that it fell within CAFA’s

“general public” exception, §1332(d)(11)(B)(ii)(III). The Fifth Circuit 

reversed, agreeing with the District Court that the suit was a mass

action but finding the general public exception inapplicable. 

Held: Because Mississippi is the only named plaintiff, this suit does not 

constitute a mass action under CAFA. Pp. 5–14. 

(a) Contrary to respondents’ argument, CAFA’s “100 or more persons” phrase does not encompass unnamed persons who are real parties in interest to claims brought by named plaintiffs. Congress knew 

how to draft language to that effect when it intended such a meaning, 

see, e.g., §§1332(d)(5)(B), 1332(d)(1)(D). That it did not do so in the 

mass action provision indicates that Congress did not want the provision’s numerosity requirement to be satisfied by counting unnamed 

individuals who possess an interest in the suit.

Respondents’ understanding also cannot be reconciled with the fact 

that the “100 or more persons” are not unspecified individuals with 
 

2 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Syllabus 

no participation in the suit but are the “plaintiffs” subsequently referred to in the provision, i.e., the very parties proposing to join their 

claims in a single trial. This is evident in two key ways. First, CAFA 

uses “persons” and “plaintiffs” the same way they are used in Federal

Rule of Civil Procedure 20, which refers to “persons” as individuals

who are proposing to join as “plaintiffs” in a single action. Second, it 

is difficult to imagine how the “claims of 100 or more” unnamed individuals could be “proposed to be tried jointly on the ground that the

. . . claims” of some completely different group of named plaintiffs

“involve common questions of law or fact.”

Construing “plaintiffs” to include both named and unnamed real 

parties in interest would stretch the meaning of “plaintiff” beyond

recognition. A “plaintiff” is commonly understood to be a party who 

brings a civil suit in a court of law, not anyone, named or unnamed,

whom a suit may benefit. Moreover, respondents’ definition would 

also have to apply to the mass action provision’s subsequent reference to “plaintiffs” in the phrase “jurisdiction shall exist only over

those plaintiffs whose claims [exceed $75,000],” §1332(d)(11)(B)(i). 

See Brown v. Gardner, 513 U. S. 115, 118. This would result in an 

administrative nightmare that Congress could not possibly have intended, see Griffin v. Oceanic Contractors, Inc., 458 U. S. 564, 575, 

where district courts would have to identify hundreds (or in this case,

hundreds of thousands) of unnamed parties whose claims are for less

than $75,000 and then decide how to dispose of their claims. Pp. 5– 

10. 

(b) Statutory context reinforces this Court’s reading of the mass action provision. CAFA provides that once removal occurs, a case shall 

not be transferred to another court “unless a majority of the plaintiffs

in the action request transfer.” §1332(d)(11)(C)(i). If “plaintiffs” included unnamed parties, it would be surpassingly difficult for a court

to poll the enormous number of real parties in interest to decide 

whether an action may be transferred. Moreover, respondents’ position that the action here should be removed because it is similar to a 

class action fails to recognize that the mass action provision functions

largely as a backstop to ensure that CAFA’s relaxed class action jurisdictional rules cannot be evaded by a suit that names a host of

plaintiffs rather than using the class device. Had Congress wanted 

CAFA to authorize removal of representative actions brought by 

States as sole plaintiffs on respondents’ theory, it would have done so

through the class action provision, not the mass action provision. 

Pp. 10–11. 

(c) This Court has interpreted the diversity jurisdiction statute to 

require courts in certain contexts to look behind the pleadings to ensure that parties are not improperly creating or destroying diversity 
 

Cite as: 571 U. S. ____ (2014) 3 

Syllabus 

jurisdiction, see, e.g., Wecker v. National Enameling & Stamping Co., 

204 U. S. 176, 185–186, but Congress did not intend this background

inquiry to apply to the mass action provision. First, it could make 

sense to incorporate the background inquiry into the mass action 

provision if the inquiry had previously been applied in a similar 

manner. That is not the case here, however, and so any presumption

that Congress wanted to incorporate the inquiry, if it exists at all,

would be comparatively weak. Second, even if the background principle had previously been applied in this manner, Congress expressly

indicated that it did not want the principle to apply to the mass action provision both through the textual indicators described above

and by prohibiting defendants from joining unnamed individuals to a 

lawsuit in order to turn it into a mass action, §1332(d)(11)(B)(ii)(II).

Requiring district courts to identify unnamed persons interested in

the suit would run afoul of that intent. Pp. 11–13. 

701 F. 3d 796, reversed and remanded. 

SOTOMAYOR, J., delivered the opinion for a unanimous Court. 
 

 

_________________ 

_________________ 

 

 

Cite as: 571 U. S. ____ (2014) 1 

Opinion of the Court 

NOTICE: This opinion is subject to formal revision before publication in the

preliminary print of the United States Reports. Readers are requested to

notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in order

that corrections may be made before the preliminary print goes to press. 

SUPREME COURT OF THE UNITED STATES 

No. 12–1036 

MISSISSIPPI EX REL. JIM HOOD, ATTORNEY 

GENERAL, PETITIONER v. AU OPTRONICS 

CORPORATION ET AL. 

ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE FIFTH CIRCUIT
 

[January 14, 2014]

 JUSTICE SOTOMAYOR delivered the opinion of the Court. 

Under the Class Action Fairness Act of 2005 (CAFA or

Act), defendants in civil suits may remove “mass actions”

from state to federal court. CAFA defines a “mass action” 

as “any civil action . . . in which monetary relief claims of

100 or more persons are proposed to be tried jointly on the

ground that the plaintiffs’ claims involve common questions of law or fact.” 28 U. S. C. §1332(d)(11)(B)(i). The 

question presented is whether a suit filed by a State as the 

sole plaintiff constitutes a “mass action” under CAFA 

where it includes a claim for restitution based on injuries 

suffered by the State’s citizens. We hold that it does not. 

According to CAFA’s plain text, a “mass action” must

involve monetary claims brought by 100 or more persons

who propose to try those claims jointly as named plaintiffs. Because the State of Mississippi is the only named

plaintiff in the instant action, the case must be remanded 

to state court. 
 

 

 

2 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Opinion of the Court 

I 

A 

Congress enacted CAFA in order to “amend the procedures that apply to consideration of interstate class actions.” 119 Stat. 4. In doing so, Congress recognized that

“[c]lass action lawsuits are an important and valuable part 

of the legal system.” CAFA §2. It was concerned, however, 

that certain requirements of federal diversity jurisdiction, 28 U. S. C. §1332, had functioned to “kee[p] cases of 

national importance” in state courts rather than federal 

courts. CAFA §2.

CAFA accordingly loosened the requirements for diversity jurisdiction for two types of cases—“class actions” and

“mass actions.” The Act defines “class action” to mean 

“any civil action filed under rule 23 of the Federal Rules of 

Civil Procedure or similar State statute or rule of judicial

procedure.” 28 U. S. C. §1332(d)(1)(B). And it defines 

“mass action” to mean “any civil action . . . in which monetary relief claims of 100 or more persons are proposed 

to be tried jointly on the ground that the plaintiffs’ 

claims involve common questions of law or fact.” 

§1332(d)(11)(B)(i).

For class and mass actions, CAFA expanded diversity 

jurisdiction in two key ways. First, it replaced the ordinary requirement of complete diversity of citizenship 

among all plaintiffs and defendants, see State Farm Fire 

& Casualty Co. v. Tashire, 386 U. S. 523, 530–531 (1967),

with a requirement of minimal diversity. Under that requirement, a federal court may exercise jurisdiction over a 

class action if “any member of a class of plaintiffs is 

a citizen of a State different from any defendant.”

§1332(d)(2)(A). The same rule applies to mass actions.

See §1332(d)(11)(A) (“[A] mass action shall be deemed . . .

removable under [§§1332(d)(2) through (d)(10)]”). Second, 

whereas §1332(a) ordinarily requires each plaintiff’s claim

to exceed the sum or value of $75,000, see Exxon Mobil 
 

 

 

Cite as: 571 U. S. ____ (2014) 3 

Opinion of the Court 

Corp. v. Allapattah Services, Inc., 545 U. S. 546, 554–555 

(2005), CAFA grants federal jurisdiction over class and 

mass actions in which the aggregate amount in controversy exceeds $5 million. §§1332(d)(2), (d)(6), (d)(11)(A).

Class and mass actions filed in state court that satisfy 

CAFA’s requirements may be removed to federal court, 28

U. S. C. §1453, but federal jurisdiction in a mass action,

unlike a class action, “shall exist only over those plaintiffs” 

whose claims individually satisfy the $75,000 amount in

controversy requirement, §1332(d)(11)(B)(i).1 

B 

Respondents manufacture liquid crystal displays, or 

LCDs. In March 2011, the State of Mississippi sued them

in state court, alleging that they had formed an international cartel to restrict competition and raise prices in

the LCD market. The State claimed that these actions violated two Mississippi statutes: the Mississippi Antitrust Act, 

Miss. Code Ann. §75–21–1 et seq. (2009), and the Mississippi Consumer Protection Act, §75–24–1 et seq. (2009 and 

Cum. Supp. 2013). The State sought injunctive relief and 

civil penalties under both statutes, along with punitive 

damages, costs, and attorney’s fees. It also sought restitution for its own purchases “of LCD products and the purchases of its citizens.” App. to Brief in Opposition 65a; 

§75–24–11.

Respondents filed a notice to remove the case from state

to federal court, arguing that the case was removable 

under CAFA as either a “class action” or a “mass action.” 

The District Court ruled that the suit did not qualify as 

a “class action” because it was “not brought pursuant to 

Federal Rule of Civil Procedure 23 or a ‘similar State 

statute or rule of judicial procedure.’” 876 F. Supp. 2d 

—————— 

1CAFA provides certain exceptions for class actions that involve matters of principally local or state concern. See 28 U. S. C. §§1332(d)(3)– 

(5). None of them are at issue in this case. 
 

 

4 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Opinion of the Court 

758, 769 (SD Miss. 2012). But it held that the suit did 

qualify as a “mass action,” because “[i]t is a civil action ‘in 

which monetary relief claims of 100 or more persons are 

proposed to be tried jointly on the ground that the plaintiffs’ claims involve common questions of law or fact.’” Id., 

at 771. The District Court reached that conclusion on the 

basis of Fifth Circuit precedent in Louisiana ex rel. Caldwell v. Allstate Ins. Co., 536 F. 3d 418 (CA5 2008), which it 

understood to “stan[d] for the proposition that the words 

‘persons’ and ‘plaintiffs’ in [the mass action definition] are 

to be defined as ‘real parties in interest.’” 876 F. Supp. 2d, 

at 771. Applying that rule, the court found that 100 or

more unidentified Mississippi consumers had purchased

LCD screens and were therefore real parties in interest to

the State’s restitution claim. Ibid. The court noted the 

“possibility that a ‘mass action’ should be thought of as a 

‘mass joinder,’”—that is, as a suit involving 100 or more 

“named plaintiffs.” Ibid., n. 9. But it deemed that interpretation to be foreclosed by Caldwell. 

The District Court nonetheless remanded the case to 

state court on the basis of CAFA’s “general public exception,” which excludes from the “mass action” definition 

“any civil action in which . . . all of the claims in the action

are asserted on behalf of the general public (and not on

behalf of individual claimants or members of a purported 

class) pursuant to a State statute specifically authorizing 

such action.” 28 U. S. C. §1332(d)(11)(B)(ii)(III). 

The Court of Appeals reversed. 701 F. 3d 796 (CA5 

2012). It agreed with the District Court’s determination

that Mississippi’s suit is not a “class action” under CAFA.2 

Id., at 799. It also agreed that, under Caldwell, the suit 

qualifies as a “mass action” because “[t]he real parties in

interest in Mississippi’s suit are those more than 100 . . .

individual citizens who purchased the [LCD] products 

—————— 

2Respondents do not challenge this ruling before this Court. 
 

Cite as: 571 U. S. ____ (2014) 5 

Opinion of the Court 

within Mississippi.” 701 F. 3d, at 800. It disagreed, however, with the District Court’s ruling that the suit falls

within the general public exception. Id., at 802–803.3 

Judge Elrod concurred in the judgment, noting that after 

the Fifth Circuit’s decision in Caldwell, three Courts of 

Appeals had deemed similar lawsuits not to be mass actions removable under CAFA.4 We granted certiorari to

resolve this split of authority, 569 U. S. ___ (2013), and 

now reverse. 

II
 

A 

Our analysis begins with the statutory text. Sebelius v. 

Cloer, 569 U. S. ___, ___ (2013) (slip op., at 6). The statute 

provides: 

“[T]he term mass action means any civil action (except

a [class action]) in which monetary relief claims of 100

or more persons are proposed to be tried jointly on

the ground that the plaintiffs’ claims involve common

questions of law or fact, except that jurisdiction shall 

exist only over those plaintiffs whose claims in a mass

action satisfy the jurisdictional amount requirements

under subsection (a).” §1332(d)(11)(B)(i). 

The parties do not dispute that this provision encompasses suits that are brought jointly by 100 or more 

named plaintiffs who propose to try their claims together. 

The question is whether the provision also includes suits 

—————— 

3The Court of Appeals did so on the rationale that because individual

Mississippi consumers are real parties in interest to the State’s restitution claim, the general public exception’s requirement that “all of

the claims” must be “asserted on behalf of the general public (and not

on behalf of individual claimants)” was not satisfied. 28 U. S. C. 

§1332(d)(11)(B)(ii)(III). 4See AU Optronics Corp. v. South Carolina, 699 F. 3d 385 (CA4 

2012); Nevada v. Bank of Am. Corp., 672 F. 3d 661 (CA9 2012); LG 

Display Co. v. Madigan, 665 F. 3d 768 (CA7 2011). 
 

6 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Opinion of the Court 

brought by fewer than 100 named plaintiffs on the theory 

that there may be 100 or more unnamed persons who are

real parties in interest as beneficiaries to any of the plaintiffs’ claims. Respondents argue that the provision covers

such suits because “claims of 100 or more persons” refers 

to “the persons to whom the claim belongs, i.e., the real 

parties in interest to the claims,” regardless of whether

those persons are named or unnamed. Brief for Respondents 19 (emphasis in original). We disagree. 

To start, the statute says “100 or more persons,” not 

“100 or more named or unnamed real parties in interest.”

Had Congress intended the latter, it easily could have 

drafted language to that effect. Indeed, when Congress

wanted a numerosity requirement in CAFA to be satisfied 

by counting unnamed parties in interest in addition to 

named plaintiffs, it explicitly said so: CAFA provides that 

in order for a class action to be removable, “the number 

of members of all proposed plaintiff classes” must be 100

or greater, §1332(d)(5)(B), and it defines “class members” 

to mean “the persons (named or unnamed) who fall within 

the definition of the proposed or certified class,” 

§1332(d)(1)(D). Congress chose not to use the phrase

“named or unnamed” in CAFA’s mass action provision, a 

decision we understand to be intentional. See Dean v. 

United States, 556 U. S. 568, 573 (2009) (“‘[W]here Congress includes particular language in one section of a 

statute but omits it in another section of the same Act, it 

is generally presumed that Congress acts intentionally 

and purposely in the disparate inclusion or exclusion’”). 

More fundamentally, respondents’ interpretation cannot

be reconciled with the fact that the “100 or more persons” 

referred to in the statute are not unspecified individuals

who have no actual participation in the suit, but instead 

the very “plaintiffs” referred to later in the sentence—the 

parties who are proposing to join their claims in a single

trial. Congress made this understanding evident in two 
 

Cite as: 571 U. S. ____ (2014) 7 

Opinion of the Court 

key ways. 

First, we presume that “‘Congress is aware of existing 

law when it passes legislation.’” Hall v. United States, 

566 U. S. ___, ___ (2012) (slip op., at 9). Here, Congress

used the terms “persons” and “plaintiffs” just as they are

used in Federal Rule of Civil Procedure 20, governing 

party joinder. Where §1332(d)(11)(B)(i) requires that the 

“claims of 100 or more persons [must be] proposed to be

tried jointly on the ground that the plaintiffs’ claims involve common questions of law or fact,” Rule 20 provides 

that “[p]ersons may join in one action as plaintiffs if they 

assert any right to relief jointly . . . and any question of 

law or fact common to all plaintiffs will arise in the action.” Thus, just as it is used in Rule 20, the term “persons” in §1332(d)(11)(B)(i) refers to the individuals who

are proposing to join as plaintiffs in a single action. 

Second, respondents’ interpretation of “persons” cannot 

square with the statute’s requirement that the claims of 

the “100 or more persons” must be proposed for joint trial

“on the ground that the plaintiffs’ claims involve common

questions of law or fact.” §1332(d)(11)(B)(i). It is difficult 

to imagine how the claims of one set of unnamed individuals could be proposed for joint trial on the ground that the 

claims of some completely different group of named plaintiffs share common questions. The better understanding 

is that Congress meant for the “100 or more persons” and

the proposed “plaintiffs” to be one and the same. 

Recognizing that the statute’s use of the term “persons” 

could be a reference to proposed plaintiffs, respondents 

assert that “plaintiffs,” like “persons,” should be construed

to “includ[e] both named and unnamed real parties in interest.” Brief for Respondents 24. But that stretches 

the meaning of “plaintiff” beyond recognition. The term 

“plaintiff” is among the most commonly understood of 

legal terms of art: It means a “party who brings a civil suit 

in a court of law.” Black’s Law Dictionary 1267 (9th ed. 
 

8 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Opinion of the Court 

2009); see also Webster’s Third New International Dictionary 1729 (1961) (defining “plaintiff” to mean “one who

commences a personal action or lawsuit,” or “the complaining party in any litigation”). It certainly does not mean 

“anyone, named or unnamed, whom a suit may benefit,” as

respondents suggest.5 

Moreover, Congress used the term “plaintiffs” twice in

the mass action provision. The provision encompasses 

actions in which monetary “claims of 100 or more persons 

are proposed to be tried jointly on the ground that the 

plaintiffs’ claims involve common questions,” and it then

provides that “jurisdiction shall exist only over those

plaintiffs whose claims in a mass action satisfy the jurisdictional amount requiremen[t]” of $75,000. §1332(d) 

(11)(B)(i). If respondents are correct that “plaintiffs”

means unnamed parties in interest where it is used the

first time, then so too the second. After all, the “presumption that a given term is used to mean the same 

thing throughout a statute” is “at its most vigorous when a 

term is repeated within a given sentence.” Brown v. 

Gardner, 513 U. S. 115, 118 (1994). 

Yet if the term “plaintiffs” is stretched to include all 

unnamed individuals with an interest in the suit, then 

§1332(d)(11)(B)(i)’s requirement that “jurisdiction shall 

exist only over those plaintiffs whose claims [exceed 

$75,000]” becomes an administrative nightmare that

Congress could not possibly have intended, see Griffin v. 

Oceanic Contractors, Inc., 458 U. S. 564, 575 (1982). How 

is a district court to identify the unnamed parties whose

claims in a given case are for less than $75,000? Would 

the court in this case, for instance, have to hold an evidentiary hearing to determine the identity of each of the 

—————— 

5Congress could of course require a real party in interest inquiry in a

statute that uses the term “plaintiff” simply by saying so. But it has 

not done that here. 
 

Cite as: 571 U. S. ____ (2014) 9 

Opinion of the Court 

hundreds of thousands of unnamed Mississippi citizens

who purchased one of respondents’ LCD products between 

1996 and 2006 (the period alleged in the complaint)? Even 

if it could identify every such person, how would it ascertain the amount in controversy for each individual claim?

Respondents suggest that “[i]n some circumstances, defendants may be able to identify from their payment records any persons who may have claims for overpayments,”

but they stop notably short of claiming to possess such

decades-old records themselves. Brief for Respondents 25. 

Furthermore, what would happen with individuals

whose claims were valued at less than $75,000? The 

District Court in this case suggested that if the suit were 

deemed a mass action, it would sever the claim for “restitution for losses incurred by individuals claiming less than

or equal to $75,000 each” and remand that claim back to 

state court, while allowing the other claims (including the 

restitution claims exceeding $75,000) to proceed in federal 

court. 876 F. Supp. 2d, at 775. Even respondents do not

defend that outcome, presumably because it would mean 

that much of the State’s lawsuit could proceed in state 

court after all, simultaneously with the newly severed

parallel federal action.6 

We think it unlikely that Congress intended that federal

district courts engage in these unwieldy inquiries. By

contrast, interpreting “plaintiffs” in accordance with its 

usual meaning—to refer to the actual named parties who 

—————— 

6Respondents suggest that a district court might be able to exercise

supplemental jurisdiction over the claims that fall beneath $75,000,

thereby avoiding the problem of identifying and remanding such claims 

to the state court. We need not decide the issue here, but we note that 

at least one Court of Appeals has rejected that view. See Lowery v. 

Alabama Power Co., 483 F. 3d 1184, 1206, n. 51 (CA11 2007) (holding

that because supplemental jurisdiction does not apply where a federal

statute “ ‘expressly provide[s] otherwise,’ ” 28 U. S. C. §1367(a), the 

mass action provision’s explicit exclusion of jurisdiction over claims 

beneath $75,000 negates supplemental jurisdiction over such claims). 
 

 

10 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Opinion of the Court 

bring an action—leads to a straightforward, easy to administer rule under which a court would examine whether 

the plaintiffs have pleaded in good faith the requisite 

amount. See Horton v. Liberty Mut. Ins. Co., 367 U. S. 

348, 353 (1961). Our decision thus comports with the

commonsense observation that “when judges must decide 

jurisdictional matters, simplicity is a virtue.” See Standard Fire Ins. Co. v. Knowles, 568 U. S. ___, ___ (2013) (slip 

op., at 6). 

B 

Our reading of the mass action provision’s text is reinforced by the statutory context. See Mohamad v. Palestinian Authority, 566 U. S. ___, ___ (2012) (slip op., at 5–6). 

First, the provision of CAFA governing transfer motions 

confirms our view that the term “plaintiffs” refers to actual

named parties as opposed to unnamed real parties in

interest. That provision, §1332(d)(11)(C)(i), provides that 

once a mass action has been removed to federal court, it 

“shall not thereafter be transferred to any other court . . .

unless a majority of the plaintiffs in the action request

transfer.” If respondents are correct that “plaintiffs” 

means “unnamed parties in interest,” it will be surpassingly difficult for a court to decide in a case like this one 

whether an action may be transferred. The District Court 

itself acknowledged this problem, noting that it would 

have to identify and communicate with “hundreds of thousands if not millions of real parties in interest” to “pol[l] 

[them] about their preferred forum” if respondents’ interpretation were correct. 876 F. Supp. 2d, at 777.

The context in which the mass action provision was 

enacted lends further support to our conclusion. Congress’ 

overriding concern in enacting CAFA was with class actions. See Preamble, 119 Stat. 4 (describing CAFA as an

“[a]ct to amend the procedures that apply to consideration

of interstate class actions”); CAFA §2 (Congress’ findings 
 

 

Cite as: 571 U. S. ____ (2014) 11 

Opinion of the Court 

with respect to class actions). The mass action provision

thus functions largely as a backstop to ensure that CAFA’s

relaxed jurisdictional rules for class actions cannot be 

evaded by a suit that names a host of plaintiffs rather

than using the class device. Respondents’ argument fails

to recognize this key distinction. Their position is ultimately that “[t]his action is similar to a class action,” such

that it should be removed. Brief for Respondents 27. But 

if Congress had wanted representative actions brought by

States as sole plaintiffs to be removable under CAFA on

the theory that they are in substance no different from 

class actions, it would have done so through the class

action provision, not the one governing mass actions.7 

III 

Rather than relying on the text of CAFA as the source of 

its real party in interest inquiry, the Court of Appeals

appeared to find such an inquiry necessary on the basis of

what it understood to be a background principle: that 

“federal courts look to the substance of the action and not 

only at the labels that the parties may attach.” Caldwell, 

536 F. 3d, at 424. This was error. 

We have interpreted the diversity jurisdiction statute to

require courts in certain contexts to look behind the pleadings to ensure that parties are not improperly creating or

destroying diversity jurisdiction. We have held, for example, that a plaintiff may not keep a case out of federal 

court by fraudulently naming a nondiverse defendant. 

Wecker v. National Enameling & Stamping Co., 204 U. S. 

176, 185–186 (1907). Nor may a plaintiff create diversity

by collusively assigning his interest in an action. Kramer 

v. Caribbean Mills, Inc., 394 U. S. 823, 825–830 (1969); 

—————— 

7The parties both point to the “general public exception,”

§1332(d)(11)(B)(ii)(III), in support of their respective positions. But 

because the foregoing arguments resolve this case, we need not construe that provision here. 
 

12 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Opinion of the Court 

see also 28 U. S. C. §1359. And in cases involving a State

or state official, we have inquired into the real party in

interest because a State’s presence as a party will destroy

complete diversity. Missouri, K. & T. R. Co. v. Missouri 

Railroad and Warehouse Comm’rs, 183 U. S. 53, 58–59 

(1901).

But the question in this case is not simply whether

there exists some background principle of analyzing the 

real parties in interest to a suit; the question is whether 

Congress intended that courts engage in that analysis

when deciding whether a suit is a mass action. Recognizing this fact, respondents do not argue that the real party

in interest inquiry employed in the above cases somehow 

supersedes the text of CAFA; they instead argue that we

should read CAFA in light of those cases because “‘Congress expects its statutes to be read in conformity with

this Court’s precedents.’” Brief for Respondents 19 (quoting United States v. Wells, 519 U. S. 482, 495 (1997)). For 

two reasons, however, we conclude that Congress did not 

intend the background inquiry to apply to the mass action

provision.

First, it makes sense to infer Congress’ intent to incorporate a background principle into a new statute where

the principle has previously been applied in a similar 

manner. But that is not the case here. The background

real party in interest inquiry identifies what party’s (or 

parties’) citizenship should be considered in determining 

diversity. The inquiry that respondents urge is quite different: It is an attempt to count up additional unnamed 

parties in order to satisfy the mass action provision’s 

numerosity requirement. Respondents offer no reason to 

believe that Congress intended to extend the real party

inquiry to this new circumstance, and so any presumption

that Congress wanted to incorporate the inquiry, if it 

exists in this case at all, would be comparatively weak. Cf. 

Meyer v. Holley, 537 U. S. 280, 286 (2003) (“Congress’ 
 

 

Cite as: 571 U. S. ____ (2014) 13 

Opinion of the Court 

silence, while permitting an inference that Congress intended to apply ordinary background tort principles,

cannot show that it intended to apply an unusual modification of those rules”).8 

Second, even if the background principle had previously 

been applied in the manner sought by respondents, Congress provided express indications that it did not want the 

principle to apply to the mass action provision. It specified that “the term ‘mass action’ shall not include any civil 

action in which . . . the claims are joined upon motion of a 

defendant.” §1332(d)(11)(B)(ii)(II). By prohibiting defendants from joining unnamed individuals to a lawsuit in 

order to turn it into a mass action, Congress demonstrated

its focus on the persons who are actually proposing to join 

together as named plaintiffs in the suit. Requiring district 

courts to pierce the pleadings to identify unnamed persons

interested in the suit would run afoul of that intent. 

Moreover, as already discussed, Congress repeatedly used 

the word “plaintiffs” to describe the 100 or more persons 

whose claims must be proposed for a joint trial. That word 

refers to actual, named parties—a concept inherently at

odds with the background inquiry into unnamed real

parties in interest, who by definition are never plaintiffs.

Congress thus clearly displaced a background real party in

interest inquiry, even assuming one might otherwise 

apply. Cf. Barnhart v. Sigmon Coal Co., 534 U. S. 438, 

459, n. 16 (2002). 

—————— 

8We have also applied a real party in interest inquiry in contexts

other than that of determining citizenship for purposes of diversity 

jurisdiction. See North Dakota v. Minnesota, 263 U. S. 365, 374–376 

(1923) (state sovereign immunity); Oklahoma ex rel. Johnson v. Cook, 

304 U. S. 387, 392–393 (1938) (original jurisdiction). But even if we 

were to indulge in a presumption that Congress somehow intended to

import the inquiry applied in those particular contexts into the mass

action provision’s distinct numerosity requirement, we would find any

such presumption overridden by CAFA’s text. 
 

 

14 MISSISSIPPI EX REL. HOOD v. AU OPTRONICS CORP. 

Opinion of the Court 

* * * 

For the foregoing reasons, the judgment of the United

States Court of Appeals for the Fifth Circuit is reversed, 

and the case is remanded for further proceedings consistent with this opinion. 

It is so ordered.