                               In the

    United States Court of Appeals
                 For the Seventh Circuit
                     ____________________
No. 19-2898
CARLTON GUNN,
                                                  Plaintiff-Appellant,
                                 v.

CONTINENTAL CASUALTY COMPANY,
                                                 Defendant-Appellee.
                     ____________________

         Appeal from the United States District Court for the
           Northern District of Illinois, Eastern Division.
          No. 1:18-cv-03314 — Charles P. Kocoras, Judge.
                     ____________________

     ARGUED APRIL 15, 2020 — DECIDED AUGUST 5, 2020
                ____________________

   Before MANION, HAMILTON, and BARRETT, Circuit Judges.
    HAMILTON, Circuit Judge. Most appellate opinions try to
answer questions of law. This opinion is an exception. We ask
many more questions than we can answer here. They concern
choice-of-law principles as applied to the unique challenges
of interstate regulation of insurance in the United States, and
more specifically as applied to a group insurance policy is-
sued in one jurisdiction to an employer with employees in
every state. We realize we are leaving a good deal of work for
2                                                 No. 19-2898

the capable district judge on remand. We hope he will receive
help on choice-of-law issues from counsel for the parties and
interested amici curiae.
    Plaintiﬀ Carlton Gunn brought this case as a putative class
action against defendant Continental Casualty Company,
which issued a group long-term care insurance policy to
Gunn’s employer, the federal judiciary, in Washington D.C.
Gunn alleged that Continental breached its contract, commit-
ted torts, and violated consumer protection laws by raising
his premiums dramatically. Continental persuaded the dis-
trict court to dismiss the case on the pleadings based on its
assertion of a filed-rate defense, relying on the Washington
state Insurance Commissioner’s approval of the new, higher
premiums for individual insureds in Washington. The parties’
briefs in the district court and on appeal raised the issue of
choice of law but oﬀered little help in resolving it.
    The appellate briefs and arguments make clear that choice
of law is critical in this case, but they leave too many unan-
swered questions. Which state’s or states’ law creates Gunn’s
causes of action? Does that jurisdiction recognize an applica-
ble filed-rate defense, and if so, what are its contours? Which
state or states have authority to approve premium rates under
the group policy? If one state otherwise oﬀers Gunn a remedy
but another state with authority has approved Continental’s
rates, which state’s authority controls and which must yield,
and why? We raised these and other questions in oral argu-
ment, but without satisfactory answers. Given their im-
portance to the larger framework of multistate insurance reg-
ulation, we conclude that the best resolution of this appeal is
to let the adversary process take its course, with some general
direction from us to ensure that the adversaries focus on the
No. 19-2898                                                    3

critical issues. We therefore reverse and remand for further
proceedings.
I. Plaintiﬀ’s Claims and Procedural Background
    Contracts for group insurance are in essence three-party
contracts. Steven Plitt et al., 1A Couch on Insurance 3d § 7:1
(1995 & supp. 2019). “A group insurance policy is the contract
between the insurer and an employer, … or some other cen-
tral entity, for the benefit of a group of people that have some
relationship to the central entity, such as employees.” Id. The
central entity, not the individual insured, holds the master
policy and has “the chief contractual relationship with the in-
surer.” Id. The individual insureds are considered third-party
beneficiaries of the master policy and “typically receive certif-
icates proving that they are insured and listing what coverage
is provided.” Id. For this reason, “the addition of new individ-
ual members to a master group policy does not create a new
contract of insurance.” Id. § 8:1. At the same time, individual
insureds are usually not automatically covered by the central
entity’s master policy. They must individually elect coverage
and pay their own premiums. Id. § 8:2.
   For purposes of defendant’s motion to dismiss, we assume
the truth of the following factual allegations. In 1999,
defendant Continental Casualty Company delivered a group
long-term care insurance policy to the federal judiciary—
specifically, to the Federal Judiciary Group Long Term Care
Insurance Trust in Washington D.C. Long-term care
insurance is intended to provide long-term financial security
by covering a variety of services, not generally covered by
Medicare or ordinary health insurance, for those unable to
care for themselves due to age or disability. As with life
insurance, the cost of long-term care insurance increases with
4                                                  No. 19-2898

age. As Continental advertised for this policy, “the younger
you are when your coverage begins, the lower your premiums
will be for the duration of your participation in the plan.”
    In 2000, plaintiﬀ Carlton Gunn was an assistant federal
defender in the State of Washington eligible for coverage
under the judiciary’s policy. He purchased coverage under
the policy, relying in part on Continental’s representation in
its marketing materials that it would raise premiums, if at all,
only “for everyone in your age category who has the kind of
coverage plan that you do.” The master policy and Gunn’s
individual coverage certificate similarly promised that
Continental would raise premiums “only if we change the
premiums for all insureds in the same premium class.” The
master policy provided specifically that “Premium is
computed as stated in the Master Application,” which
contained tables of premium rates according to payment
schedule, age on eﬀective date of coverage, and amount of
daily benefit. No mention was made of rates varying based on
the individual insured’s state of residence.
    To protect against the long-term eﬀects of inflation on the
policy’s costs and benefits, Gunn also purchased what Conti-
nental called a “Lifetime Compound Automatic Benefit In-
crease benefit.” That feature would “automatically increase
the daily benefit for nursing home care that you select now by
5% annually on a compounded basis.” “This means,” Conti-
nental explained, “you will not need to worry about increas-
ing your premium in the future.” Purchasing the automatic
benefit increase feature more than doubled Gunn’s baseline
premium.
   Seventeen years later, Gunn received a letter from Conti-
nental informing him that his premium rates would rise by 25
No. 19-2898                                                        5

percent each year for the next three years, adding up to a near
doubling of the premium, from about $700 to about $1,400 an-
nually. The letter also said that the eﬀective dates of the in-
creases would depend ultimately on the approval of “certain
states,” which might or might not be forthcoming at the same
time, or at all. Gunn believes this geographic disparity
breaches Continental’s promise to raise rates only uniformly
within a “premium class.” He also contends he should be pro-
tected from the dramatic premium increases precisely be-
cause he had already paid to protect himself against inflation
by buying the automatic benefit increase.
    Gunn’s complaint asserted claims for breach of contract,
breach of implied covenant, unfair and deceptive practices
under the District of Columbia’s consumer protection statute,
fraud, and fraudulent concealment. On behalf of himself and
a putative class of insureds under the judiciary’s group pol-
icy, Gunn sought rescission (whether of the master policy or
his individual certificate, he did not say) and an injunction
against further rate increases, or alternatively compensatory,
statutory, and punitive damages.1
    Continental moved to dismiss under Federal Rule of Civil
Procedure 12(b)(6), arguing among other grounds that the
complaint was barred by “the filed-rate doctrine.” The federal
version of that doctrine in general “forbids a regulated entity
to charge rates for its services other than those properly filed
with the appropriate federal regulatory authority.” Arkansas
Louisiana Gas Co. v. Hall, 453 U.S. 571, 577 (1981). One way to
put it is that the “reasonableness” of a rate is an


   1 No member of this panel is a member of the plan, so we would not
be members of a potential plaintiff class.
6                                                    No. 19-2898

administrative standard, not a justiciable legal right. Montana-
Dakota Utils. Co. v. Northwestern Pub. Serv. Co., 341 U.S. 246,
251 (1951). Another is that a buyer’s consent to pay the filed
rate is not necessary to create an obligation to pay the filed
rate. Lowden v. Simonds-Shields-Lonsdale Grain Co., 306 U.S.
516, 520–21 (1939). Arkansas Louisiana Gas itself held that a
state-law action for breach of contract could not survive
preemption based on a state court’s “speculation” that the re-
sponsible federal regulator would have approved the higher
rate for which the parties contracted instead of the lower rate
it had actually approved. 453 U.S. at 573, 578–79.
   States have adopted versions of this doctrine of varying
breadth and force, some in statutes and some through case
law. And even where diﬀerent states’ doctrines diﬀer only in
nuance, we have said that “nuance can be important.” In re
Rhone-Poulenc Rorer, Inc., 51 F.3d 1293, 1300 (7th Cir. 1995) (re-
versing certification of nationwide class whose claims were
governed by many diﬀerent states’ laws).
    Citing Arkansas Louisiana Gas and other cases, Continental
argued that Gunn’s individual certificate had been issued to
him in the State of Washington; that the Washington insur-
ance commissioner had authority to approve the rates Gunn
was charged; and that Continental had sought and obtained
the Washington commissioner’s approval for the challenged
rate increases. Gunn’s suit, went the argument, amounted to
a collateral attack on rates duly approved by the commis-
sioner, so that the filed-rate doctrine prohibited courts from
entertaining Gunn’s claims. We confess that we were mysti-
fied when we realized that Continental’s motion did not ex-
plain whether the filed-rate doctrine it invoked stems from
federal or state law, let alone from which state’s law.
No. 19-2898                                                     7

    In opposition, Gunn argued that the law of the District of
Columbia does not recognize a version of the filed-rate doc-
trine that would bar his claims. Neither side’s briefs to the dis-
trict court engaged in a meaningful choice-of-law analysis,
nor did they develop their competing assertions of legislative
and regulatory jurisdiction over the rates Gunn should pay.
    The district court also did not engage with the choice-of-
law problem, but it agreed with Continental that Gunn’s suit
was the type of attack on duly approved rates generally
barred by filed-rate rules and dismissed the complaint with
prejudice. We have jurisdiction of the appeal under 28 U.S.C.
§ 1291.
II. Analysis
   A. The Choice-of-Law Problem
     We review de novo a grant of a motion to dismiss for fail-
ure to state a claim. Warciak v. Subway Restaurants, Inc.,
949 F.3d 354, 356 (7th Cir. 2020). A Rule 12(b)(6) motion tests
“the legal suﬃciency of a complaint,” as measured against the
standards of Rule 8(a). E.g., Runnion v. Girl Scouts of Greater
Chicago and Northwest Indiana, 786 F.3d 510, 526 (7th Cir. 2015).
It is the defendant’s burden to establish the complaint’s insuf-
ficiency. Yeksigian v. Nappi, 900 F.2d 101, 104 (7th Cir. 1990).
    There is procedural problem in this case, however, that
made defendant’s use of Rule 12(b)(6) inappropriate. Conti-
nental did not actually challenge the complaint’s suﬃciency,
at least by invoking the filed-rate doctrine. Continental in-
stead advanced an aﬃrmative defense, which it had the bur-
den of pleading and proving. Fed. R. Civ. P. 8(c)(1) (burden of
pleading); Benson v. Fannie May Confections Brands, Inc.,
944 F.3d 639, 645 (7th Cir. 2019) (burden of proving); see E. &
8                                                     No. 19-2898

J. Gallo Winery v. EnCana Corp., 503 F.3d 1027, 1039 n.11 (9th
Cir. 2007) (filed-rate doctrine as aﬃrmative defense). With a
narrow and pragmatic exception for a plaintiﬀ who has
pleaded herself out of court, the appropriate vehicle for re-
solving an aﬃrmative defense is a motion for judgment on the
pleadings under Rule 12(c), not a Rule 12(b)(6) motion. Ben-
son, 944 F.3d at 645; see also Burton v. Ghosh, 961 F.3d 960, 964–
65 (7th Cir. 2020) (collecting cases); cf. Brooks v. Ross, 578 F.3d
574, 579 (7th Cir. 2009) (example of pragmatic exception
where complaint unambiguously set forth dates establishing
statute-of-limitations defense). “Observing the distinction is
necessary to allocate correctly the burdens of pleading and
proof,” H.A.L. N.Y. Holdings, LLC v. Guinan, 958 F.3d 627, 632
(7th Cir. 2020), and serves an important notice function. Bur-
ton, 961 F.3d at 965, citing Blonder-Tongue Labs., Inc. v. Univ. of
Illinois Found., 402 U.S. 313, 350 (1971), among others.
    In this case, Continental’s filed-rate defense certainly drew
on materials outside the complaint and was not appropriate
for a Rule 12(b)(6) motion. Gunn did not plead himself out of
court with one stray reference to the Washington state insur-
ance commissioner, so an answer and motion under Rule
12(c), not a Rule 12(b)(6) motion, would have been the appro-
priate path to raise a filed-rate defense. We construe Conti-
nental’s motion as one under Rule 12(c), and Continental bore
the burden of showing that the allegations of the complaint
and an answer showed that an aﬃrmative defense conclu-
sively defeated all of Gunn’s claims as a matter of law. See
Alexander v. City of Chicago, 994 F.2d 333, 336 (7th Cir. 1993).
   Regardless of the procedural bobble, Continental had to
address an indispensable threshold question: under the law
of what sovereign was it entitled to judgment? Law “does not
No. 19-2898                                                                  9

exist without some definite authority behind it.” Black & White
Taxicab & Transfer Co. v. Brown & Yellow Taxicab & Transfer Co.,
276 U.S. 518, 533 (1928) (Holmes, J., dissenting). Claims and
defenses have to come from somewhere. “Proof of [them] in
the air, so to speak, will not do.” Palsgraf v. Long Island R.R.
Co., 162 N.E. 99, 99 (N.Y. 1928). Yet that has basically been
Continental’s approach.
    In support of its motion to dismiss, Continental assumed
without argument that the applicable law was Washington’s,
though Gunn pleaded at least one cause of action arising un-
der a statute of the District of Columbia. On appeal, Continen-
tal asserts, again without argument, that Washington law cre-
ates Gunn’s causes of action and, astonishingly, claims that
“federal common law” creates its filed-rate defense. But Con-
tinental does not argue for federal preemption.2 Nor does the



    2  Chief Judge Howell denied dismissal in a recent case similar to
Gunn’s, noting that a filed-rate defense “typically” has a basis in federal
statute and in that context “supports the supremacy of federal regulation
over certain federal as well as state and common law claims.” Krukas v.
AARP, Inc., 376 F. Supp. 3d 1, 18 (D.D.C. 2019). In Krukas, the court as-
sumed for purposes of argument that some version of a filed-rate doctrine
could apply to insurance regulation and denied dismissal because the
plaintiff did not directly challenge any regulated rates. Id. at 20−26. Fed-
eral law leaves insurance regulation and pricing to the States. 15 U.S.C.
§ 1011. In this context, it is “neither prudent nor appropriate for a federal
court to impose the filed-rate doctrine on a state which has not adopted it,
nor should a court stretch or bend a state doctrine to more comfortably fit
the contours of the federal rule.” Bhasker v. Kemper Cas. Ins. Co., 284 F.
Supp. 3d 1191, 1233 (D.N.M. 2018) (denying dismissal of insurance claims
based on filed-rate doctrine), quoting Clark v. Prudential Ins. Co. of Am., No.
CIV. 08-6197, 2011 WL 940729, at *10 (D.N.J. Mar. 15, 2011) (denying mo-
tion to strike insurance class claims based on filed-rate doctrine).
10                                                            No. 19-2898

doctrine aﬀect federal jurisdiction.3 Continental has not ex-
plained why, in Gunn’s case arising under state law, federal
law (let alone the narrow niches of federal common law that
have survived Erie Railroad) could be relevant at all. See Erie
R.R. Co. v. Tompkins, 304 U.S. 64 (1938); Williams v. Jader Fuel
Co., Inc., 944 F.2d 1388, 1400 (7th Cir. 1991) (“the legal and fac-
tual suﬃciency of an aﬃrmative defense is examined with ref-
erence to state law”).
    Because Continental did not identify the source of govern-
ing law, we have little trouble concluding that it did not show
properly that it was entitled to judgment based on this free-
floating defense.
    The more diﬃcult question is what to do about it. “The
matter of what questions may be taken up and resolved for
the first time on appeal is one left primarily to the discretion
of the courts of appeals.” Singleton v. Wulﬀ, 428 U.S. 106, 121
(1976). But the record here oﬀers little guidance. Gunn also
did not engage on the choice-of-law issue.
   We must say frankly that the parties let the district court
down. The parties each asserted their choice-of-law positions,
and they clearly signaled that the choice of law could be deci-
sive. But the parties went no farther than those assertions; nei-
ther side supported its position. The district court did not make



     3 There is no suggestion here or reason to think that any version of the

filed-rate doctrine affects a federal court’s subject-matter jurisdiction. See
Wilson v. EverBank, N.A., 77 F. Supp. 3d 1202, 1233 n.6 (S.D. Fla. 2015) (col-
lecting cases holding filed rates go to merits, not jurisdiction); see also
Krukas, 376 F. Supp. 3d at 14 n.5 (distinguishing “nonjusticiability” ra-
tionale for filed-rate doctrine from Article III justiciability).
No. 19-2898                                                     11

its own choice of law but cited filed-rate cases from many
state and federal courts.
    We recognize that an appeal is too late to raise a choice-of-
law issue for the first time and we are under no obligation to
do so on our own initiative. “We are busy enough without
creating issues that are unlikely to aﬀect the outcome of the
case (if they were likely to aﬀect the outcome the parties
would be likely to contest them).” Wood v. Mid-Valley Inc.,
942 F.2d 425, 427 (7th Cir. 1991). In this case, however, both
sides raised the choice-of-law issue but then oﬀered the dis-
trict court (and us) little help.
    Choice of law may well be decisive here. The relevant is-
sues are doubtful enough, and the stakes high enough for our
state-based systems of decentralized insurance regulation,
that they are better addressed by the district court in the first
instance, perhaps with help from interested friends of the
court who can provide insight into those systems and their
relationship to one another. See, e.g., Harris v. KBR Servs., Inc.,
724 F.3d 458, 462 (3d Cir. 2013) (remanding for initial choice-
of-law determination where necessary to review dismissal for
non-justiciability).
   B. Considerations on Remand
       1. Illinois Choice-of-Law Rules Control
    We begin with the fundamentals. A federal court exercis-
ing its diversity jurisdiction over state-law claims applies the
choice-of-law rules of the state in which it sits. Klaxon Co. v.
Stentor Elec. Mfg. Co., 313 U.S. 487 (1941). Here, that state is
Illinois, which applies forum law unless an actual conflict
with another state’s law is shown, Bridgeview Health Care Ctr.
v. State Farm Fire & Cas. Co., 10 N.E.3d 902, 905 (Ill. 2014), or
12                                                   No. 19-2898

the parties agree that forum law does not apply. See Belleville
Toyota, Inc. v. Toyota Motor Sales, U.S.A., Inc., 770 N.E.2d 177,
194 (Ill. 2002). Neither Gunn nor Continental seeks applica-
tion of Illinois law, and the laws of the District of Columbia
and Washington appear likely, at a minimum, to give diﬀer-
ent eﬀect to the acts of the Washington state insurance com-
missioner. The analysis then turns to which state’s law ap-
plies. Bridgeview, 10 N.E.3d at 905.
    In general, Illinois follows the Restatement (Second) of
Conflict of Laws (Am. Law Inst. 1971). Barbara’s Sales, Inc. v.
Intel Corp., 879 N.E.2d 910, 919 (Ill. 2007). For claims on a con-
tract, the Second Restatement usually enforces the parties’
contractual choice of law, see § 187, which may extend to tort
claims “dependent” on the contract. Facility Wizard Software,
Inc. v. Southeastern Technical Servs, LLC, 647 F. Supp. 2d 938,
943 (N.D. Ill. 2009). In this case, however, the parties’ contract
contains no choice-of-law provision.
    Absent eﬀective party choice, to govern issues in contract
the Second Restatement chooses the “local” law (that is, the
substantive law excluding choice-of-law rules) of the state
which, “with respect to that issue, has the most significant re-
lationship to the transaction and the parties.” § 188(1). To gov-
ern issues in tort, the Second Restatement similarly chooses
the law of the state which, “with respect to that issue, has the
most significant relationship to the occurrence and the par-
ties.” § 145(1). These general standards oﬀer little direct guid-
ance in resolving particular cases. See Barbara’s Sales,
879 N.E.2d at 920. But the Second Restatement also supplies
“a secondary statement in black letter setting forth the choice
of law rules in a given situation.” Id. (quotation marks omit-
ted). These “specific presumptive rules” provide more
No. 19-2898                                                      13

concrete points of departure. Townsend v. Sears, Roebuck & Co.,
879 N.E.2d 893, 902 (Ill. 2007).
    For claims regarding a group life insurance contract, the
Second Restatement’s presumptive rule is that “rights against
the insurer are usually governed by the law which governs
the master policy.” § 192 cmt. h. That is usually the law of the
employer’s principal place of business, where the master pol-
icy was delivered. Id. The Illinois Supreme Court has cited this
rule with approval in the context of group health insurance.
Hofeld v. Nationwide Life Ins. Co., 322 N.E.2d 454, 458 (Ill. 1975).
The Couch treatise is in accord as to group insurance gener-
ally, 1A Couch on Insurance § 8:7, and we have reached the
same conclusion as to group accident insurance under Indi-
ana’s version of the “most significant relationship” test. Horn
v. Transcon Lines, Inc., 7 F.3d 1305, 1307–08 (7th Cir. 1993). Ap-
plied to this case, comment h to section 192 of the Second Re-
statement seems to suggest that Illinois would choose District
of Columbia law to govern Gunn’s claim for breach of con-
tract.
    As for Gunn’s tort claims (unfair and deceptive consumer
practices, fraud, and fraudulent concealment), the Second Re-
statement’s presumptive rule for torts of deception provides
that if the place of defendant’s deception and the place of
plaintiﬀ’s reliance on it were the same, the law of that place
applies. § 148(1). If deception and reliance took place in dif-
ferent states, a list of relevant contacts guides the court’s de-
termination of what jurisdiction has “the most significant re-
lationship” to the case. § 148(2). Illinois has applied section
148 to consumer fraud claims. Barbara’s Sales, 879 N.E.2d at
922. Applied to this case, section 148 suggests Illinois may
choose either District of Columbia or Washington law to
14                                                               No. 19-2898

govern Gunn’s tort claims, depending on whether it would
legally characterize Continental’s alleged misrepresentations
as having been made to Gunn in Washington or to his em-
ployer in the District of Columbia.4
         2. The Filed-Rate Doctrine in the District of Columbia
    “In the District of Columbia, the filed rate doctrine is stat-
utorily mandated.” District of Columbia v. D.C. Pub. Serv.
Comm’n, 905 A.2d 249, 256 (D.C. 2006), citing D.C. Code § 34-
603. The statutory scheme within which the mandate is em-
bedded provides that every public utility in the District must
file proposed rate changes with the D.C. Public Service Com-
mission for the Commission’s approval. § 34-901(c)–(d). The
statutory filed-rate rule provides that rates approved by the
Commission “shall be prima facie reasonable until finally
found otherwise in an action brought for that purpose.” § 34-
603; see also § 34-1129 (“It shall be unlawful for any public
utility to … receive a greater or less compensation for any ser-
vice performed by it within the District of Columbia … than



     4 We note one wrinkle in Illinois conflicts law that may or may not
bear on this case. Illinois recognizes the doctrine of dépeçage, or “cutting
into pieces” a single claim and subjecting different issues to different ju-
risdictions’ laws. Spinozzi v. ITT Sheraton Corp., 174 F.3d 842, 848 (7th Cir.
1999). Even if Illinois would choose District of Columbia law to govern
one or more of Gunn’s claims, perhaps Illinois might choose Washington
law to govern Continental’s defenses if it determined that Washington
had the most significant relationship to the case with respect to a specific
issue, such as the filed-rate defense. See Doctor’s Data, Inc. v. Barrett, 170 F.
Supp. 3d 1087, 1107 (N.D. Ill. 2016) (recognizing possibility of splitting
claims from defenses under principle of dépeçage); see generally Restate-
ment (Second) § 6 (factors relevant to “most significant relationship” anal-
ysis).
No. 19-2898                                                       15

is specified in such printed schedules … as may at the time be
in force.”).
    The problem for Continental’s defense, however, is that
this statutory language says nothing about insurers, which
are not included in the definition of “public utilities.” See § 34-
214. Nor does the statute address the District’s insurance reg-
ulator or insurance premiums. We have found no District of
Columbia case or statute applying filed-rate principles in the
insurance context. We also have found no District of Colum-
bia case recognizing a filed-rate defense to a suit for breach of
a promise as to how premiums would be computed, still less
to a suit for fraud. Dicta suggest the District of Columbia may
recognize a common law filed-rate doctrine not anchored in a
specific statute, see Watergate East, Inc. v. D.C. Pub. Serv.
Comm’n, 662 A.2d 881, 889 (D.C. 1995) (statute “amounts to a
codification of the filed rate doctrine”), but if such a doctrine
exists, its contours are yet to be revealed. After all, a legislative
decision to adopt the doctrine in one context (public utilities)
could be understood as a legislative choice not to adopt it in
others (like insurance). And at any rate, the District would still
have to balance the policies underlying filed-rate rules against
its own consumer protection policies. See, e.g., McCarthy Fi-
nance, Inc. v. Premera, 347 P.3d 872, 875 (Wash. 2015) (“But
while a court must be cautious not to substitute its judgment
on proper rate setting for that of the relevant agency, the leg-
islature has directed that the [consumer protection statute] be
liberally construed.”).
    Even if the District of Columbia otherwise recognizes a
common law filed-rate doctrine broad enough to bar Gunn’s
claims, it also is not clear whether such a doctrine would ap-
ply to enforce the decision of a diﬀerent jurisdiction’s
16                                                   No. 19-2898

regulator. Continental’s brief assumes that the public law of
Washington must in all events, and in all courts, trump the
private law of the District of Columbia. Traditionally, how-
ever, courts have been reluctant to enforce the public law of
other states. See Restatement (First) of Conflict of Laws § 610
(Am. Law Inst. 1934) (“No action can be maintained on a right
created by the law of a foreign state as a method of furthering
its own governmental interests.”); id., cmt. c (“No action can
be maintained by a foreign state to enforce its license …
laws”); Moore v. Mitchell, 30 F.2d 600, 604 (2d Cir. 1929) (L.
Hand, J., concurring) (“To pass upon the provisions for the
public order of another state is, or at any rate should be, be-
yond the powers of a court”).
    Why would District of Columbia law privilege Washing-
ton state’s interest in the authority of its insurance commis-
sioner above the District’s own interest in aﬀording a remedy
to injured plaintiﬀs whom it would otherwise protect? See
Emory v. Grenough, 3 U.S. (3 Dall.) 369, 370 n. (1797), translat-
ing 2 Ulrich Huber, Praelectiones Juris Romani et Hodierni, ch.
“De Conflictu Legum” (1689) (“By the courtesy of nations,
whatever laws are carried into execution, within the limits of
any government, are considered as having the same eﬀect
every where, so far as they do not occasion a prejudice to the
rights of the other governments, or their citizens.”); Joseph
Story, Commentaries on the Conflict of Laws 33 (1834) (“It is dif-
ficult to conceive, upon what ground a claim can be rested, to
give to any municipal laws an extra-territorial eﬀect, when
those laws are prejudicial to the rights of other nations, or
their subjects.”), approving Huber, supra. The District of Co-
lumbia has an interest in protecting those subject to its laws
from unfair and deceptive business practices. See Shaw v. Mar-
riott Int’l, Inc., 605 F.3d 1039, 1045 (D.C. Cir. 2010). Perhaps
No. 19-2898                                                     17

more to the point, the District of Columbia has an interest in
enforcing contracts negotiated and performed there, Wright v.
Sony Pictures Entm’t, Inc., 394 F. Supp. 2d 27, 32 (D.D.C. 2005),
and the nature of group insurance suggests the master policy
in this case fits that description. It is not clear the District of
Columbia could or would subordinate those interests to the
regulatory interests of the State of Washington.
       3. The Filed-Rate Doctrine in Washington State
    The State of Washington recognizes a “common law filed
rate doctrine” not grounded in any statute. McCarthy Finance,
Inc. v. Premera, 347 P.3d 872, 875 (Wash. 2015). The doctrine
has been applied to bar state consumer protection claims chal-
lenging health insurance premiums that had been approved
by the state insurance commissioner. Id. at 876. But claims un-
der the state consumer protection law or for breach of contract
that are “merely incidental” to rates approved by the commis-
sioner are not barred. Harvey v. Centene Mgmt. Co., 357 F.
Supp. 3d 1073, 1083 (E.D. Wash. 2018) (denying motion to dis-
miss in part), quoting McCarthy, 347 P.3d at 875.
    “[W]hile a court must be cautious not to substitute its
judgment on proper rate setting for that of the relevant
agency, the legislature has directed that the [consumer pro-
tection statute] be liberally construed … . In most cases, courts
must consider [such] claims even when the requested dam-
ages are related to agency-approved rates.” McCarthy,
347 P.3d at 875. Accordingly, to the extent Washington state
law applies, Gunn’s claims may or may not be barred depend-
ing on whether they are deemed “merely incidental” to or
“would necessarily require courts to reevaluate” the commis-
sioner’s approval of Continental’s rates, as the Washington
Supreme Court—and no other court—would apply that
18                                                    No. 19-2898

distinction. Harvey, 357 F. Supp. 3d at 1083, quoting McCarthy,
347 P.3d at 875.
       4. Multistate Regulation of Group Insurance
    In the McCarran–Ferguson Act of 1945, Congress
essentially insulated state regulation of “the business of
insurance” from the dormant Commerce Clause and from
implied federal preemption. 15 U.S.C. §§ 1011–1012; see
American Ins. Ass’n v. Garamendi, 539 U.S. 396, 427–28 (2003)
(“state regulation … will be good against preemption by
federal legislation unless that legislation specifically relates to
the business of insurance” (quotation marks omitted)); Group
Life & Health Ins. Co. v. Royal Drug Co., 440 U.S. 205, 218 n.18
(1979) (“States are free to regulate insurance companies
without fear of Commerce Clause attack.”). Given the
national reach of so many insurance companies and of group
insurance policies issued to national employers, regulation of
such group policies poses important choice-of-law questions.
    Continental’s understanding of those challenges leads it to
assert that its promise of interstate uniformity in a group in-
surance policy was illusory. “[L]ike all long-term care insur-
ers,” Continental says, it “must seek approval of rate increases
on a state-by-state basis.” Continental says that the necessity
is so obvious that a reasonable customer should have known
that any promises of uniform rates among similarly situated
insureds should not have been believed. Continental’s posi-
tion is startling, but we have been given no support—as a mat-
ter of law, custom, or reason—for its central assumption that
the proper regulatory subject is the individual certificate of a
customer like Gunn rather than the employer’s master policy
under which the individual certificates are issued.
No. 19-2898                                                     19

    A necessary foundation for a filed-rate defense is the reg-
ulator’s “jurisdiction to determine the reasonableness of
rates.” McCarthy, 347 P.3d at 875. Washington asserts, as it can
assert, legislative and regulatory jurisdiction over only in-
state activity. See Midwest Title Loans, Inc. v. Mills, 593 F.3d
660, 666 (7th Cir. 2010), quoting Healy v. Beer Inst., 491 U.S.
324, 337 (1989); Dean Foods Co. v. Brancel, 187 F.3d 609, 614–15
(7th Cir. 1999), quoting Bonaparte v. Tax Court, 104 U.S. 592,
594 (1881); Wash. Rev. Code § 48.01.020. As to ratemaking,
Washington requires that every company “engaged in the
business of making contracts of insurance” file its proposed
rates with the insurance commissioner for approval or disap-
proval. Wash. Rev. Code § 48.01.050; see §§ 48.19.040,
48.19.060. The question then is how to describe the legal ge-
ography of a group insurance policy with an employer and
master policy in one location and individual insureds all over
the nation. More than one state has at least arguable interests
in such national policies and the individual certificates issued
under them.
    As noted above, the key contractual event in group insur-
ance transactions is generally held to be delivery of the master
policy, not the individual certificates issued under it. See
1A Couch on Insurance § 8:1 (“the addition of new individual
members to a master group policy does not create a new con-
tract of insurance.”). Apparently on the same understanding,
Washington’s current statutory regulation of group long-term
care insurance applies to “a long-term care insurance policy
or contract that is delivered or issued for delivery in this state”
and “any certificate issued under a group long-term care in-
surance policy that has been delivered or issued for delivery
in this state.” Wash. Rev. Code § 48.83.020. (The long-term
care insurance statute in force in 2000, when Gunn first
20                                                  No. 19-2898

obtained coverage, did not address group insurance specifi-
cally. See Wash. Rev. Code § 48.84.020; Wash. Admin. Code
§ 284-54-010.) So we might expect the Washington state insur-
ance commissioner to care about master policies delivered in
Washington and about certificates issued, no matter where or
to whom, under master policies delivered in Washington.
    That would make good multistate sense. If universalized,
it would mean that every group policy has one and only one
regulator, steering clear of the regulatory Scylla avoided in
the private-law context by the usual choice-of-law rule. See
Horn v. Transcon Lines, Inc., 7 F.3d 1305, 1307 (7th Cir. 1993)
(“There is only one policy and one form of certificate evidenc-
ing coverage. We cannot imagine why Liberty Mutual would
prefer a choice-of-law approach under which 50 diﬀerent
rules govern the same policy of insurance”); Restatement
(Second) § 192 cmt. h (“it is desirable that each individual in-
sured should enjoy the same privileges and protection”); 1A
Couch on Insurance § 8:7 (“This rule prevents the same policy
from being interpreted according to the law of potentially 50
states thus creating uniformity in the coverage and protection
of every individual insured under the group policy.”).
   But Continental proceeded on nearly the opposite as-
sumption in 2015, when it sought the challenged rate in-
creases. Continental wrote the Washington insurance com-
missioner:
       The new premium rates will be applied to all in-
       sureds under group policies that were sitused in
       your state except insureds under the group pol-
       icies sitused in your state that were issued cer-
       tificates in another state that is an extraterrito-
       rial (ET) jurisdiction. These insureds are
No. 19-2898                                                    21

       governed by the other ET state’s laws and regu-
       lations and will be included in that state for rate
       increase purposes. The new premium rates will
       also be applied to insureds issued in your state
       under groups sitused outside of your state.
As we read this letter, Continental submitted rates to the com-
missioner for every individual certificate issued in Washing-
ton, even if the master policy had not been delivered there,
but not for every master policy delivered in Washington, if the
certificate was issued in an “extraterritorial jurisdiction”
(which appears to describe Washington as well).
    The briefs do not explain what is an “extraterritorial juris-
diction,” what makes it one, or whether the District of Colum-
bia is one, nor did counsel at oral argument. We assume that
interstate regulation of insurance transactions involves a
good deal of comity and agreement among regulators of dif-
ferent states, without each regulator always pushing for max-
imum power. Any state’s claim to extraterritorial power mer-
its further inquiry, at least. Continental’s letter to the Wash-
ington insurance commissioner suggests if nothing else that
its basic position is overstated: at least some states, those that
are not “extraterritorial jurisdictions,” are content to leave
ratemaking authority in the hands of the regulator where the
master policy was delivered, even if certificates under that
policy are issued to insureds within their own borders.
    Untying this knot is not possible on the record now before
us. But it is essential to even a threshold determination of the
validity of any filed-rate defense that would give decisive ef-
fect to the decisions of the Washington state insurance com-
missioner. We must remand this task to the capable district
judge, who may find it useful to enlist the help of interested
22                                                  No. 19-2898

amici, including the National Association of Insurance Com-
missioners, associations of insurance companies, and perhaps
others who can educate generalist federal courts about the
broader implications of choice-of-law rules as applied to
group insurance policies.
    We acknowledge the questions we have posed are more
easily asked than answered. And we have not framed or dis-
cussed those questions with any intention to prejudge the cor-
rect outcome(s) in this case. The district court may find that a
motion under Rule 12(c), a motion for summary judgment on
a more complete record, or perhaps a motion for class certifi-
cation could bring the issues into sharper relief. See In re
Bridgestone/Firestone, Inc., 288 F.3d 1012, 1015 (7th Cir. 2002).
Those are case management issues best left to the district
court’s discretion. The judgment of the district court is
REVERSED and the case is REMANDED for further proceed-
ings consistent with this opinion.
