                              In the
 United States Court of Appeals
               For the Seventh Circuit
                          ____________

No. 06-2384
CAROL PASTOR, on behalf of herself
   and all others similarly situated,
                                                  Plaintiff-Appellant,
                                  v.


STATE FARM MUTUAL AUTOMOBILE
   INSURANCE COMPANY,
                                                 Defendant-Appellee.
                          ____________
             Appeal from the United States District Court
        for the Northern District of Illinois, Eastern Division.
              No. 05 C 1459—Suzanne B. Conlon, Judge.
                          ____________
     ARGUED NOVEMBER 30, 2006—DECIDED MAY 23, 2007
                          ____________


 Before POSNER, KANNE, and EVANS, Circuit Judges.
  POSNER, Circuit Judge. The district court in this class-
action suit denied class certification, and we exercised
our discretion under Fed. R. Civ. P. 23(f) to decline to
accept an appeal from that denial. But then the defendant
made and the plaintiff accepted a modest offer of judg-
ment (Fed. R. Civ. P. 68), which terminated the case and
so enabled the plaintiff to appeal as a matter of right in
order to challenge the denial of class certification, be-
2                                               No. 06-2384

cause her acceptance of the offer did not resolve the
dispute between the unnamed class members and the
defendant and so did not render the case moot. Deposit
Guaranty National Bank v. Roper, 445 U.S. 326, 332-33, 336-37
(1980); Greisz v. Household Bank (Illinois), N.A., 176 F.3d
1012, 1015 (7th Cir. 1999).
  Eleven years ago, the windshield of Carol Pastor’s car
was damaged in an accident. She had the windshield
repaired, which took about an hour (perhaps even less—
her recollection is spotty) and filed a claim with her auto
insurer, State Farm. State Farm paid her repair bill but did
not give her an additional $10 that she claims she was
owed by virtue of a clause in the insurance policy that
obliges State Farm to “pay you $10 per day if you do not
rent a car while your car is not usable.” (If the insured
does rent a car while her own car is unusable, State Farm
pays a portion of the rental charge.) The period of entitle-
ment is to begin, “if your car can run, when you leave it at
the shop for agreed repairs” and to end when the car has
been repaired; if as a result of the accident the car cannot
run, the period starts with the accident. The plaintiff
did not rent a car while her car was being repaired—that
would have been absurd, considering how brief the peri-
od was. But neither did she ask State Farm for the addi-
tional $10 to which she now claims to be entitled. She
contends that the company had a contractual duty to notify
her that she was entitled to the money, though there is
nothing in the policy to suggest that upon receipt of a
claim seeking reimbursement of one cost (the cost of
repairing the windshield) the insurer must determine and
inform the insured of any additional entitlement that the
policy might confer on her, just in case its customers don’t
bother to read their insurance policies when they file
claims under them.
No. 06-2384                                                  3

  Pastor filed this suit (a diversity suit governed by Illinois
law) shortly before the expiration of the 10-year statute of
limitations applicable to a suit in Illinois on a written
contract. She seeks to represent a class consisting of all
State Farm insureds who during the limitations period
received payments for claims for damage to their vehicles,
did not rent a car, yet did not receive any payment pursu-
ant to the $10 a day clause. Although the class members’
claims are small, the Class Action Fairness Act authorizes
the aggregation of class members’ claims to satisfy the
minimum amount in controversy required in a diversity
suit, which in the case of a suit governed by the Act is
$5 million. 28 U.S.C. § 1332(d)(6).
  The district court thought the case unmanageable as a
class action, since the contractual entitlement of each
member of the class would depend on whether and how
long the car was out of service (without the owner’s rent-
ing a replacement vehicle) because it was being repaired,
and on whether the member notified State Farm that the
car was out of service (and for how long) and that he
hadn’t rented a car and was therefore entitled to $10 a day
for x days. The plaintiff acknowledges that a determina-
tion that the car was out of service, etc., would have to be
made for each class member, but argues that the insureds
at least have no duty to notify the company of the $10 a
day claim. In so arguing she relies on internal documents
of State Farm that instruct its employees to explain to its
insureds their options, including the $10 reimbursement
for each day that an insured whose car is unusable does
not rent a replacement. Being internal to State Farm, these
documents did not communicate to the insureds an offer
that upon acceptance would have contractually entitled
them not to read their policies. Even if the documents did
4                                                 No. 06-2384

create so improbable a duty, the insured would have to
inform State Farm, or State Farm have to be informed
through some other route, that the insured’s car was out of
service; and whether it was informed would be a separate
issue with respect to every class member.
  But at least, Pastor adds, it would be feasible to make a
class-wide determination of whether, as she contends and
State Farm denies, a “day” in the clause means any part of
a day, however small, in which the car is unusable, or
whether it means 24 hours. She relies for her interpreta-
tion of “day” on a subsequent version of the clause in
which State Farm made explicit that “day” means 24 hours.
But whether it would be feasible to resolve such an issue on
a class-wide basis, which is to say whether the relevant
interpretive principles are uniform across the states
whose laws would govern the various class members’
claims, is academic, because her interpretation of “day” is
groundless. The subsequent version of the clause, in
which State Farm made explicit that “day” means 24 hours,
and which State Farm describes as a clarification, Pastor
deems a confession that her interpretation of the original
clause is correct. Obviously it is not a confession. And to
use at a trial a revision in a contract to argue the meaning
of the original version would violate Rule 407 of the
Federal Rules of Evidence, the subsequent-repairs rule,
by discouraging efforts to clarify contractual obligations,
thus perpetuating any confusion caused by unclarified
language in the contract. Rule 407 is not limited to “repair”
in the literal sense. Dusenbery v. United States, 534 U.S. 161,
172-73 (2002); Lust v. Sealy, Inc., 383 F.3d 580, 585 (7th Cir.
2004); Dennis v. County of Fairfax, 55 F.3d 151, 154-56 (4th
Cir. 1995). It was applied to the meaning of an insurance
clause in Hickman v. GEM Ins. Co., 299 F.3d 1208, 1213-
No. 06-2384                                                  5

14 and n. 9 (10th Cir. 2002). And in Maddox v. City of Los
Angeles, 792 F.2d 1408, 1417 (9th Cir. 1986), a disciplinary
proceeding was deemed a “subsequent repair.” Pastor
wants to use the evidence that State Farm, to avert future
liability to persons in the position of the plaintiff, changed
the policy, to establish State Farm’s “culpable conduct.”
That is one of the grounds that evidence of subsequent
corrective action may not be used to establish.
  State Farm argues that in any event the relevant interpre-
tive principles are not uniform across states, and in particu-
lar that states vary greatly in their willingness to admit
extrinsic evidence to contradict the apparent meaning of a
written contract; and since the proposed class embraces
all 45 jurisdictions (44 states plus the District of Columbia)
in which State Farm offered the coverage in question, the
district court could not—State Farm argues—determine
the meaning of the contract without splitting the class
into separate classes. Illinois’s choice of law principles,
which govern this litigation because Illinois is the state in
which the suit was brought, probably would refer to the
law of other states to determine the rights of at least some
of the class members. Illinois gives greatest weight in its
choice of law determinations to the jurisdiction in which
the insured risk is located, Emerson Electric Co. v. Aetna
Casualty & Surety Co., 743 N.E.2d 629, 639-40 (Ill. App.
2001); Society of Mount Carmel v. National Ben Franklin Ins.
Co., 643 N.E.2d 1280, 1286-87 (Ill. App. 1994); Massachusetts
Bay Ins. Co. v. Vic Koenig Leasing, Inc., 136 F.3d 1116, 1122-
23 (7th Cir. 1998) (Illinois law), and in this case it would be
where the car became unusable, at least if that was also
the state in which the insured usually used the car. Allen
v. State Farm Mutual Automobile Ins. Co., 574 N.E.2d 55, 59-
61 (Ill. App. 1991). Many states would fit the bill.
6                                                  No. 06-2384

   This would be a powerful objection to a class-wide
determination of the class members’ rights were it true
that the dispute over the contract’s meaning would be
resolved differently in different states because of differ-
ences in state law. But it is not true. If a contract is clear on
its face, extrinsic evidence is admissible only to establish a
latent ambiguity, which is to say an ambiguity that ap-
pears only when the contract is placed in its real-world
context. E.g., Gilmer v. Stone, 120 U.S. 586, 588-91 (1887);
Rossetto v. Pabst Brewing Co., 217 F.3d 539, 542-43 (7th
Cir. 2000); Sault Ste. Marie Tribe of Chippewa Indians v.
Granholm, 475 F.3d 805, 811-12 (6th Cir. 2007); Connect
Communications Corp. v. Southwestern Bell Telephone, L.P.,
467 F.3d 703, 709-10 (8th Cir. 2006). So in the famous case
of Raffles v. Wichelhaus, 2 H. & C. 906, 159 Eng. Rep. 375 (Ex.
1864), a suit for breach of a contract to deliver cotton by a
ship called the Peerless, the contract was clear on its face
but became ambiguous when evidence was presented
that there were two ships by that name to which the
contract might equally well have referred. As far as we
know, all states allow extrinsic evidence to “ambiguate” a
contract clear as written only if there is a latent ambiguity.
State Farm, seemingly ignoring its long-run interests as a
frequent defendant in breach of contract suits, argues that
“multiple” states permit extrinsic evidence to be con-
sidered in all suits for breach of contract, basing this heresy
on scattered judicial language taken out of context.
  The plaintiff manages to fog up the issue by presenting
a chart which purports to show that 37 states never allow
extrinsic evidence in a contract case. But the cases it
relies on for this heresy merely state the general proposi-
tion that unambiguous contracts are to be interpreted as
written, without recourse to extrinsic evidence that might
No. 06-2384                                                  7

contradict the literal meaning. E.g., Wright v. State, 700 N.E.
2d 1153 (Ind. App. 1998); Kraft v. Mason, 668 So. 2d 679, 685
(Fla. App. 1996). The latent-ambiguity doctrine is an
exception recognized by the same courts that state the
general rule. Simon Property Group, L.P. v. Michigan Sporting
Goods Distributors, Inc., 837 N.E.2d 1058, 1070-71 (Ind. App.
2005); RX Solutions, Inc. v. Express Pharmacy Services, Inc.,
746 So. 2d 475, 476-77 (Fla. App. 1999); Landis v. Mears, 329
So. 2d 323, 325-26 (Fla. App. 1976).
  The obstacle to class certification in this case lies else-
where. Questions of contract interpretation are only a
small part of the overall dispute. Individual hearings
would be necessary to determine whether a class member
made a claim for his $10 a day, whether his car was
unusable, and if so for how long. The plaintiff argues that
whenever a car is damaged, it must be unusable, for no
matter how short a time. But that is wrong, since some
people don’t bother to have a damaged car repaired, and
many damaged cars are drivable. And if a damaged car
can still be driven, a claim under the $10 a day clause
requires proof that the car was in a repair shop. Not all
damaged cars that are repaired are repaired in repair
shops. Damage to windshields—the damage of which
Pastor complains—is a type of automobile damage fre-
quently repaired by mobile units, and even if these are
“[repair] shop[s]” within the meaning of the insurance
policy, a car sitting in the driver’s driveway undergoing
repair by a mobile repair unit for minor damages
would still be drivable; in an emergency the driver could
interrupt the mobile repair and whisk off.
  The size of the class has not been determined. But it
surely consists of many thousands of persons, consider-
ing that State Farm is the largest auto insurer in the coun-
try, with literally tens of millions of auto insurance cus-
8                                                No. 06-2384

tomers (which makes it reasonably likely that the suit
meets the Class Action Fairness Act’s requirement of a
$5 million minimum amount in controversy), and con-
sidering too the length of the period of limitations. The
revision of the $10 a day clause will have diminished the
size of the class somewhat, but we don’t know by how
much.
  The picture of a federal district judge presiding
over thousands of evidentiary hearings each involving a
trivial amount of money is not a pretty one. In these
circumstances the judge was right to deny class certifica-
tion, Isaacs v. Sprint Corp., 261 F.3d 679, 681-82 (7th Cir.
2001); Szabo v. Bridgeport Machines, Inc., 249 F.3d 672, 677-
78 (7th Cir. 2001), though not because class actions are
poorly suited to aggregating small claims. Quite the
contrary—if a class member has a large enough stake to
be able to litigate on his own, the case for class-action
treatment is weakened. Nagel v. ADM Investor Services,
Inc., 217 F.3d 436, 443 (7th Cir. 2000). “The policy at the
very core of the class action mechanism is to overcome
the problem that small recoveries do not provide the in-
centive for any individual to bring a solo action prosecut-
ing his or her rights.” Mace v. Van Ru Credit Corp., 109 F.3d
338, 344 (7th Cir. 1997), quoted in Amchem Products, Inc. v.
Windsor, 521 U.S. 591, 617 (1997). But when a separate
evidentiary hearing is required for each class member’s
claim, the aggregate expense may, if each claim is very
small, swamp the benefits of class-action treatment. And
that is the case here.
  Of course this means as a practical matter that no mem-
ber of the class, except Pastor, will recover under the $10 a
day clause in a court of general jurisdiction even if entitled
to such relief, because even as augmented by interest and
No. 06-2384                                                 9

multiplied by the number of days that the car was in the
shop the claim would be too slight to make a lawsuit
worth bringing. (A further complication is that the ques-
tion of prejudgment interest would be answered differ-
ently by the different states whose laws govern the claims
of the various class members, because the $10 a day
entitlement is not liquidated but instead depends on the
length of time the insured’s car was unusable. See Michael
S. Knoll, “A Primer on Prejudgment Interest,” 75 Tex. L.
Rev. 293, 297-98 (1996); Anthony E. Rothschild, Comment,
“Prejudgment Interest: Survey and Suggestion,” 77 Nw. U.
L. Rev. 192, 194-95 (1982).) Unlike a class action dominated
by issues common to the entire class, there would be no
significant economies from consolidating the class mem-
bers’ tiny claims, each requiring its own evidentiary
hearing; the expense and burden to the parties and to the
judiciary would exceed the value of the claims. This does
not mean that the class members are remediless, but they
will have to seek their remedies in small-claims courts.
   It remains to consider an issue concerning compliance
with Seventh Circuit Rule 28(a)(1), which requires the
jurisdictional statement in a diversity case to specify both
the state (or other jurisdiction) in which a corporate party
is incorporated and the state in which the party’s principal
place of business is located. The purpose of the rule is to
remind the lawyers who practice in this court that for
purposes of the diversity jurisdiction a corporation is a
citizen of two states (though they may coincide): the
state in which the corporation is incorporated and the
state in which its principal place of business is located.
State Farm is a corporation, so the appellant’s jurisdictional
statement was required to specify both states. All the
statement said, however, was that State Farm “is a citizen
10                                               No. 06-2384

of Illinois.” That is correct, because State Farm is both
incorporated in and has its principal place of business
in Illinois. But the statement does not comply with the
rule. And the corporate status of State Farm is not trans-
parent, since it is a mutual insurance company rather than
a conventional business corporation and does not have
“corporation” or “inc.” in its name, although in fact it is
incorporated and all corporations (including business,
charitable, and religious corporations) are treated the
same for purposes of determining whether the require-
ments of diversity jurisdiction are satisfied. Wise v.
Wachovia Securities, LLC, 450 F.3d 265, 267 (7th Cir. 2006);
Hoagland ex rel. Midwest Transit, Inc. v. Sandberg, Phoenix &
von Gontard, P.C., 385 F.3d 737, 740-43 (7th Cir. 2004); Kuntz
v. Lamar Corp., 385 F.3d 1177, 1182-83 (9th Cir. 2004); Saxe,
Bacon & Bolan, P.C. v. Martindale-Hubbell, Inc., 710 F.2d
87, 89 (2d Cir. 1983). “To paraphrase Gertrude Stein, for
purposes of diversity jurisdiction a corporation is a cor-
poration is a corporation.” Coté v. Wadel, 796 F.2d 981,
983 (7th Cir. 1986). (The jurisdictional statement even
failed to mention that State Farm is a corporation, though
Fed. R. App. P. 28(a)(4)(A) requires the appellant’s juris-
dictional statement to indicate “the basis for the district
court’s or agency’s subject-matter jurisdiction.”)
   Circuit Rule 28 further requires (in subsection (b)) that
the appellee’s jurisdictional statement state whether
the appellant’s jurisdictional statement is “complete and
correct.” This is a further check on our court’s assuming
jurisdiction of a case over which we lack jurisdiction.
State Farm, though represented by a major Chicago law
firm (McDermott Will & Emery) that should know better,
certified mistakenly that the appellant’s jurisdictional
statement was indeed complete and correct.
No. 06-2384                                                11

  We issued an order to show cause why the parties’
lawyers should not be sanctioned for violating our cir-
cuit rule, and they have responded. The sin in this case is
venial, and we will not impose sanctions; the burden of
responding to the order was punishment enough. But we
note a mistake in State Farm’s response to our order. It
says that its jurisdictional statement is “complete and
correct” because State Farm is in fact a citizen of Illinois
(and only Illinois), as the appellant’s jurisdictional state-
ment asserted. But State Farm is wrong (again): a juris-
dictional statement that violates Circuit Rule 28 is not
complete and correct.
 Still, the order to show cause is discharged. The judg-
ment of the district court is
                                                  AFFIRMED.
A true Copy:
       Teste:

                          _____________________________
                          Clerk of the United States Court of
                            Appeals for the Seventh Circuit




                   USCA-02-C-0072—5-23-07
