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 TRAVELERS CASUALTY AND SURETY COMPANY
   OF AMERICA ET AL. v. THE NETHERLANDS
        INSURANCE COMPANY ET AL.
                (SC 19089)
 Rogers, C. J., and Palmer, Zarella, Eveleigh, McDonald, Espinosa and
                             Robinson, Js.
       Argued February 25—officially released August 5, 2014

  Susan L. Miller, with whom was Margaret A. Casey,
for the appellants (named defendant et al.).
  Jane I. Milas, with whom was Anita C. DiGioia,
for the appellee (defendant Lombardo Brothers Mason
Contractors, Inc.).
 Lee H. Ogburn, pro hac vice, with whom, on the brief,
was Laura Pascale Zaino, for the appellees (plaintiffs).
                         Opinion

   ROBINSON, J. The plaintiffs, Travelers Casualty and
Surety Company of America and Travelers Indemnity
Company (collectively, Travelers), brought this declara-
tory judgment action against the defendants, who
include The Netherlands Insurance Company (Nether-
lands) and Lombardo Brothers Mason Contractors, Inc.
(Lombardo).1 Travelers sought and received a judgment
from the trial court declaring, inter alia, that Nether-
lands was obligated to defend Lombardo, and pay to
Travelers its pro rata share of the costs incurred in
defending Lombardo in the civil action arising from
Lombardo’s role in the construction of the leak prone
library at the University of Connecticut School of Law
(law library), chronicled in our recent decision in State
v. Lombardo Bros. Mason Contractors, Inc., 307 Conn.
412, 420– 21, 54 A.3d 1005 (2012) (underlying action).
Netherlands appeals2 from that declaratory judgment,
and raises a plethora of appellate issues, namely, that
the trial court improperly: (1) concluded that Travelers
had standing to bring this action because it was not
a party to the commercial general liability insurance
policies (CGL policies) that Netherlands had issued to
Lombardo; (2) determined that the allegations recited
in the complaint in the underlying action (underlying
complaint), constituted an occurrence under the CGL
policies; (3) concluded that the exclusion for ‘‘known
injury or damage’’ in the CGL policies did not preclude
coverage; (4) found that the pro rata allocation period
for defense costs was 144 months; (5) denied Nether-
lands’ motion for permission to amend its answer and
special defenses to assert the special defense of unclean
hands; and (6) prohibited it from presenting evidence
of unclean hands. We disagree and, accordingly, we
affirm the judgment of the trial court.
  The record reveals the following background facts,
as set forth in the trial court’s memorandum of decision,
and procedural history. ‘‘In 1994, the state of Connecti-
cut (state) contracted with Lombardo to perform
masonry for the construction of the [law library], which
was completed in 1996. In the underlying complaint,
the state alleges that in the months and years following
the completion of the project, the state began to experi-
ence problems with water intrusion in the [law] library.
Over the years, the alleged water intrusion proved to
be continuing and progressive, to the point where the
state retained forensic engineers to investigate the full
extent and likely cause of the problem. On February
14, 2008, the state initiated a lawsuit against Lombardo
and other entities seeking to recover approximately $18
million that it alleged was necessary to repair defects
in the law library.3
  ‘‘From 1994 to 2008, the following insurance carriers
assumed Lombardo’s risk: September 30, 1994 to August
31, 1998, Travelers, [CGL] Policies; August 31, 1998 to
August 31, 2000, Lumbermens [Insurance Company
(Lumbermens)], [CGL] Policies; August 31, 2000 to June
30, 2006, Netherlands, [CGL] Policies and Peerless
[Insurance Company (Peerless)], umbrella general lia-
bility policies.
  ‘‘In late 2005, Lombardo notified its insurance carriers
of the state’s potential claim against it and Travelers
agreed to participate in the investigation and related
defense. Lumbermens . . . and Netherlands refused,
however, to participate in the investigation and defense.
Prior to trial, Travelers spent over $482,855 defending
Lombardo.’’ (Footnotes altered.)
   In July, 2009, Travelers filed a two count complaint
against Netherlands, Peerless, Lumbermens and Lom-
bardo.4 In the first count, Travelers sought, inter alia,
a declaratory judgment that: (1) Peerless, Netherlands5
and Lumbermens ‘‘are obligated to pay their pro rata
shares of the cost of Lombardo’s defense’’; and (2)
‘‘Lombardo is required to pay the pro rata share of its
defense costs allocated to any uninsured period in the
underlying action going forward . . . .’’ In the second
count, alleging ‘‘equitable subrogation,’’ Travelers
alleged that it had paid the full cost of defending Lom-
bardo, and sought reimbursement from Netherlands
and Lumbermens of their pro rata share of the defense
costs with respect to the underlying claim and underly-
ing action. In response, Netherlands filed an answer
and five special defenses wherein it contended that
coverage was unavailable under both the primary CGL
policies issued by Netherlands and the umbrella policies
issued by Peerless.
   With respect to the special defense that is at issue
in this appeal, Netherlands pleaded that it had no obliga-
tion to reimburse defense costs because Lombardo had
been on notice of problems with the law library ‘‘on
or before January, 2000,’’ and, therefore, prior to the
issuance of the first Netherlands CGL policy in August,
2000, meaning that ‘‘the exclusion for prior known
occurrences or claims . . . applies and no coverage is
available for Lombardo under any of the policies listed
in paragraph 1a of this first special defense.’’6
  The matter proceeded to a one day court trial before
the court, Hon. Joseph Q. Koletsky, judge trial referee.7
At trial, Travelers withdrew the second count of its
complaint claiming a right to equitable subrogation.
Shortly thereafter, Netherlands moved to dismiss this
case for lack of subject matter jurisdiction, claiming
that Travelers, which was not a party to Lombardo’s
insurance contracts, now lacked standing to assert the
remaining declaratory judgment claim in the complaint.
The trial court denied that motion to dismiss, conclud-
ing that Travelers had standing to bring this declaratory
judgment action.
  The trial court then issued a memorandum of decision
rendering judgment for Travelers, declaring that: ‘‘Neth-
erlands had a duty to defend based on the underlying
complaint.’’ In reaching this conclusion, the trial court
first determined that the factual allegations in the under-
lying complaint ‘‘state that the damage potentially falls
within the dates of Netherlands’ coverage.’’8 The trial
court held that the ‘‘occurrence which triggered the
duty to defend was the water intrusion into the law
library,’’9 and rejected Netherlands’ reliance on the
known injury or damage clause, noting that ‘‘the under-
lying complaint does not state with certainty when Lom-
bardo was aware of the actual damage.’’10 In a
subsequent articulation; see Practice Book § 66-5; the
trial court found that Netherlands was obligated to pay
48.6 percent of Lombardo’s defense costs, which it
determined by dividing the 70 month coverage period,
from August 31, 2000 to June 30, 2006, ‘‘by the entire
allocation period of 144 months.’’ This appeal followed.
  On appeal, Netherlands claims that the trial court
improperly: (1) denied its motion to dismiss this declar-
atory judgment action; (2) concluded that the facts
recited in the underlying complaint constituted an
occurrence under the CGL policies; (3) concluded that
the exclusion for ‘‘known injury or damage’’ in the CGL
policies did not preclude coverage; (4) determined that
the allocation period for the insurers’ pro rata share of
the defense costs was 144 months; (5) denied its motion
for permission to amend the answer and special
defenses to assert the special defense of unclean hands;
and (6) precluded it from introducing evidence of
unclean hands. We address each claim in turn, setting
forth additional relevant facts and procedural history
where necessary.
                             I
                 MOTION TO DISMISS
  We begin with Netherlands’ claim that the trial court
improperly denied its motion to dismiss this declaratory
judgment action and, specifically, the first and only
remaining count in the complaint, for lack of subject
matter jurisdiction. Netherlands relies on Wilson v. Kel-
ley, 224 Conn. 110, 116, 617 A.2d 433 (1992), as standing
for the proposition that General Statutes § 52-29,11 the
declaratory judgment statute, does not create an inde-
pendent cause of action or ‘‘substantive rights that did
not otherwise exist.’’ Citing, inter alia, Dow & Condon,
Inc. v. Brookfield Development Corp., 266 Conn. 572,
833 A.2d 908 (2003), Netherlands contends that the first
count alleges breach of contract between it and Lom-
bardo and that, because Travelers is neither a party to
Netherlands’ insurance contracts with Lombardo nor
an intended third party beneficiary thereof, Travelers
lacks standing to bring this claim. To this end, Nether-
lands cites a Superior Court decision, Century Indem-
nity Co. v. Northeast Utilities, Superior Court, judicial
district of New Britain, Docket No. CV-98-0495496-S
(May 24, 1999), as holding that ‘‘an insurer does not
have standing to sue to enforce insurance contracts
between its insured and other insurers, although, under
certain circumstance[s], it may have a claim for equita-
ble contribution.’’ Thus, Netherlands contends that
Travelers ‘‘deprived itself’’ of standing when it withdrew
its equitable claims at trial.
   In response, Travelers, joined by Lombardo, first con-
tends that subject matter jurisdiction exists because it
withdrew the equitable subrogation claim for the sole
reason that the parties had agreed that the case would
be tried only under the first count, seeking only a per-
centage determination as to the parties’ pro rata respon-
sibility for defense; the parties agreed to this litigation
posture because attorney-client privilege issues arising
from the pending underlying action precluded the dis-
covery necessary to arrive at a money judgment on the
equitable subrogation count. Citing three other Superior
Court decisions,12 Travelers then claims that it is classi-
cally aggrieved, which gives it the requisite standing to
bring a declaratory judgment action under § 52-29 and
the implementing rule of practice, Practice Book § 17-
55,13 with respect to the duty to defend as between
carriers with a mutual insured. Although Travelers is
neither a party to, nor an intended beneficiary of, an
insurance policy between Lombardo, its insured, and
Netherlands, they argue that Travelers’ aggrievement is
established by the fact that it has paid all of Lombardo’s
defense costs to date and that Netherlands has refused
to defend Lombardo or contribute to the defense costs
incurred by Travelers. Further, as a policy matter, Lom-
bardo observes that it ‘‘is not unusual that an insured
against whom a large claim has been made is often not
in the best financial position to bring and prosecute a
declaratory judgment action against multiple insurers,’’
and states that it, of course, has a ‘‘very real interest
. . . with respect to the responsibilities of the various
carriers to provide a defense,’’ given the ongoing litiga-
tion in the underlying action. We agree with Travelers
and Lombardo, and conclude that the trial court prop-
erly denied the motion to dismiss because Travelers
had standing to bring this declaratory judgment action.
   The record reveals the following additional relevant
facts and procedural history. On the day of the court
trial in this case, counsel for Travelers explained that
it was withdrawing the second count of the complaint,
which sought a money judgment requiring, inter alia,
Netherlands ‘‘to pay to Travelers [Netherlands’] pro rata
share of the sums paid by Travelers to defend Lombardo
against the underlying claim from February 25, 2003,
forward and against the underlying action,’’ because of
attorney-client privilege issues with respect to Lom-
bardo that resulted from the still pending underlying
action.14 Counsel for Travelers explained that, should
the court agree with its argument that Netherlands was
obligated to pay 48.6 percent of Lombardo’s defense
costs, the parties ‘‘will, between us, sort out what 48.6
percent of those bills is.’’ Counsel for Netherlands con-
firmed that understanding,15 although a subsequent dis-
cussion with the trial court appeared to raise the
question of whether the requested declaration of a per-
centage would be appropriately rendered under the first
count, rather than the withdrawn second count.16 Fur-
ther action was not taken at that point, after Nether-
lands’ counsel stated her belief that the request for a
declaratory judgment in the first count was an ‘‘equita-
ble action,’’ particularly insofar as Netherlands’ pending
request to amend the special defenses to assert an equi-
table defense of unclean hands pertained to both counts
of the complaint.
  After the one day court trial, Netherlands moved to
dismiss for lack of subject matter jurisdiction, claiming
that Travelers’ withdrawal of the equitable subrogation
count deprived it of standing to assert the sole
remaining declaratory judgment claim in the complaint
because Travelers was not a party to Lombardo’s insur-
ance contracts with Netherlands and Peerless. The trial
court denied the motion to dismiss, concluding that
Travelers had standing to proceed in this declaratory
judgment action under the factors set forth in Practice
Book § 17-55 and Connecticut Business & Industry
Assn., Inc. v. Commission on Hospitals & Health Care,
218 Conn. 335, 346–47, 589 A.2d 356 (1991). Relying
primarily on the application of those factors in Travel-
ers Property Casualty Co. of America v. Continental
Casualty Co., judicial district of New London, Docket
No. CV-08-4008325-S (December 29, 2008) (47 Conn. L.
Rptr. 18, 20–21), the trial court held that Travelers had
standing to bring this declaratory judgment action
because: ‘‘Netherlands’ denial of Lombardo’s claim obli-
gated Travelers to defend Lombardo, thereby injuri-
ously affecting Travelers more than members of the
general community. Travelers also has a very practical
interest in a declaration of Netherlands’ obligations
under its policy; it could require or compel Netherlands
to participate in Lombardo’s defense.’’
   ‘‘The purpose of a declaratory judgment action, as
authorized by . . . § 52-29 and Practice Book § [17-55],
is to secure an adjudication of rights [when] there is a
substantial question in dispute or a substantial uncer-
tainty of legal relations between the parties. . . . Sub-
divisions (1) and (2) of Practice Book § 17-55
respectively require that the plaintiff in a declaratory
judgment action have an interest, legal or equitable, by
reason of danger of loss or of uncertainty as to the
party’s rights or other jural relations and that there be
an actual bona fide and substantial question or issue
in dispute or substantial uncertainty of legal relations
which requires settlement between the parties . . . .
This court previously has observed that our declaratory
judgment statute provides a valuable tool by which
litigants may resolve uncertainty of legal obligations.
. . .
   ‘‘We also have recognized that our declaratory judg-
ment statute is unusually liberal. An action for declara-
tory judgment . . . is a statutory action as broad as it
well could be made. . . . Indeed, our declaratory judg-
ment statute is broader in scope than . . . the statutes
in most, if not all, other jurisdictions . . . and [w]e
have consistently construed our statute and the rules
under it in a liberal spirit, in the belief that they serve a
sound social purpose. . . . [Although] the declaratory
judgment procedure may not be utilized merely to
secure advice on the law . . . it may be employed in a
justiciable controversy where the interests are adverse,
where there is an actual bona fide and substantial ques-
tion or issue in dispute or substantial uncertainty of
legal relations which requires settlement, and where all
persons having an interest in the subject matter of the
complaint are parties to the action or have reasonable
notice thereof. . . .
  ‘‘One type of controversy to which our declaratory
judgment statute often has been applied is a dispute
over rights and liabilities under an insurance policy.’’
(Citations omitted; internal quotation marks omitted.)
New London County Mutual Ins. Co. v. Nantes, 303
Conn. 737, 747–48, 36 A.3d 224 (2012); see also St. Paul
Fire & Marine Ins. Co. v. Shernow, 22 Conn. App. 377,
380, 577 A.2d 1093 (1990) (‘‘[t]here is no question that
a declaratory judgment action is a suitable vehicle to
test the rights and liabilities under an insurance
policy’’).
   ‘‘It is a basic principle of our law . . . that the plain-
tiffs must have standing in order for a court to have
jurisdiction to render a declaratory judgment. . . .
Standing is the legal right to set judicial machinery in
motion. One cannot rightfully invoke the jurisdiction
of the court unless he [or she] has, in an individual or
representative capacity, some real interest in the cause
of action, or a legal or equitable right, title or interest
in the subject matter of the controversy. . . . When
standing is put in issue, the question is whether the
person whose standing is challenged is a proper party
to request an adjudication of the issue . . . . [Because]
[s]tanding requires no more than a colorable claim of
injury . . . a [party] ordinarily establishes . . . stand-
ing by allegations of injury [that he or she has suffered
or is likely to suffer]. Similarly, standing exists to
attempt to vindicate arguably protected interests.’’
(Citation omitted; internal quotation marks omitted.)
Bysiewicz v. DiNardo, 298 Conn. 748, 758, 6 A.3d
726 (2010).
  Put differently, an ‘‘action for a declaratory judgment,
valuable as it has become in modern practice, is not a
procedural panacea for use on all occasions. . . . In
providing statutory authority for courts to grant declara-
tory relief, the legislature did not intend to broaden
their function so as to include issues which would not
be such as could be determined by the courts in ordinary
actions. . . . The declaratory judgment procedure con-
sequently may be employed only to resolve a justiciable
controversy where the interests are adverse, where
there is an actual bona fide and substantial question
or issue in dispute or substantial uncertainty of legal
relations which requires settlement. . . . A party pur-
suing declaratory relief must therefore demonstrate, as
in ordinary actions, a justiciable right in the controversy
sought to be resolved, that is, contract, property or
personal rights . . . as such will be affected by the
[court’s] decision . . . . A party without a justiciable
right in the matter sought to be adjudicated lacks stand-
ing to raise the matter in a declaratory judgment action.’’
(Citations omitted; internal quotation marks omitted.)
Connecticut Business & Industry Assn., Inc. v. Com-
mission on Hospitals & Health Care, supra, 218
Conn. 347–48.
   Thus, ‘‘[s]tanding is established by showing that the
party claiming it is authorized by statute to bring suit
or is classically aggrieved. . . . The fundamental test
for determining [classical] aggrievement encompasses
a well-settled twofold determination: first, the party
claiming aggrievement must successfully demonstrate
a specific, personal and legal interest in [the subject
matter of the challenged action], as distinguished from
a general interest, such as is the concern of all members
of the community as a whole. Second, the party claiming
aggrievement must successfully establish that this spe-
cific personal and legal interest has been specially and
injuriously affected by the [challenged action]. . . .
Aggrievement is established if there is a possibility, as
distinguished from a certainty, that some legally pro-
tected interest . . . has been adversely affected.’’
(Internal quotation marks omitted.) Wilcox v. Webster
Ins., Inc., 294 Conn. 206, 214–15, 982 A.2d 1053 (2009).
   Finally, it is well settled that ‘‘[i]t is the burden of
the party who seeks the exercise of jurisdiction in his
favor . . . clearly to allege facts demonstrating that he
is a proper party to invoke judicial resolution of the
dispute. . . . It is well established that, in determining
whether a court has subject matter jurisdiction, every
presumption favoring jurisdiction should be indulged.
. . . Because a determination regarding the trial court’s
subject matter jurisdiction raises a question of law, our
review is plenary.’’ (Internal quotation marks omitted.)
Bysiewicz v. DiNardo, supra, 298 Conn. 758–59.
  The question in this appeal, then, is whether an entity
that is not a named insured or otherwise party to certain
insurance policies may demonstrate ‘‘a specific, per-
sonal and legal interest in [those] policies’’ that would
give it standing to commence a declaratory judgment
action. Wilcox v. Webster Ins., Inc., supra, 294 Conn.
215. This requires us to address the split of authority
that arises from the ‘‘potential problem [when] a declar-
atory judgment is sought by one of the insurers against
the other, since the two entities are not in the usual
course of events in any cognizable legal relationship
with each other.’’17 16 L. Russ & T. Segalla, Couch on
Insurance (3d Ed. 2005) § 227:42, pp. 227-58 through
227-59. We agree, however, with the vast majority of
federal and sister state authorities that have considered
this question, which support the leading commentators’
view that it is ‘‘properly within the competent authority
of a court to hear [an action for] declaratory judgment
. . . relating to the rights and obligations of two insur-
ance companies as to the coverage of their respective
policies, where the pleadings embrace and present this
ultimate and controlling issue.’’18 Id., § 232:63, p. 232-
85. This includes questions as to the insurers’ duty to
defend. See id., § 232:65, p. 232-90. Indeed, federal case
law is especially persuasive because ‘‘[o]ur rules of
practice, [mirror] the federal constitutional ‘case or con-
troversy’ requirement . . . .’’ (Citation omitted.) Con-
necticut Business & Industry Assn., Inc. v.
Commission on Hospitals & Health Care, supra, 218
Conn. 346–47, citing Flast v. Cohen, 392 U.S. 83, 95, 88
S. Ct. 1942, 20 L. Ed. 2d 947 (1968).
  There are two lines of federal authority on this issue
supporting the general proposition that, when a cover-
age dispute arises, one insurer has the standing to bring
a declaratory judgment action against another insurer
in order to determine the existence or allocation of a
duty to defend a common insured party, despite the
fact that they are not parties to each other’s insurance
policies with that common insured. One line of cases,
exemplified by the decision of the United States Court
of Appeals for the Eleventh Circuit in Provident Life &
Accident Ins. Co. v. Transamerica-Occidental Life Ins.
Co., 850 F.2d 1489, 1492–93 (11th Cir. 1988), cert.
denied, 489 U.S. 1081, 109 S. Ct. 1534, 103 L. Ed. 2d 839
(1989), conditions that standing on the creation of the
requisite case and controversy via (1) the inclusion of
the insured as a necessary party to the declaratory
judgment action, or (2) a reservation of rights
agreement between the two insurers, prior to one or
both defending or indemnifying their common insured.19
Although Travelers would have standing under Provi-
dent Life & Accident Ins. Co. because it named Lom-
bardo as a defendant in this declaratory judgment
action, we, however, find more persuasive the other line
of cases, exemplified by United Services Automobile
Assn. v. Royal-Globe Ins. Co., 511 F.2d 1094, 1095–96
(10th Cir. 1975), which does not so require.
  Accordingly, we turn to a detailed review of United
Services Automobile Assn. v. Royal-Globe Ins. Co.,
supra, 511 F.2d 1094, wherein the United States Court
of Appeals for the Tenth Circuit persuasively rejected
arguments akin to those of Netherlands in this appeal.
That case was a declaratory judgment action brought
to determine whether the United Services Automobile
Association (USAA), which was the insurer of a minor
who had been involved in an accident while driving a
rental car, was obligated to defend and indemnify that
minor, as opposed to Royal-Globe Insurance Company
(Royal), who was the rental company’s insurer. Id.,
1095. ‘‘Royal challenge[d] USAA’s standing to bring [the]
[declaratory judgment] action,’’ noting that ‘‘USAA is
not a direct beneficiary of the rental contract, Royal
invokes the settled and familiar rule that an action by
a third party to enforce a contract may be brought
only when the third party is a direct beneficiary of
the contract.’’ Id., 1096. The Tenth Circuit rejected this
argument ‘‘simply because this action is not one to
enforce a contract but rather seeks a declaration of
the relative rights and duties of USAA and Royal. The
subject matter of the suit—the duty to defend and
indemnify [the minor] in the pending Texas lawsuit—
is definite and substantial. Each party has a stake in
the outcome, and their interests are adverse.’’ Id.; see
also, e.g., Phico Ins. Co. v. Providers Ins. Co., 888 F.2d
663, 667 (10th Cir. 1989) (concluding that insurance
company had standing to bring declaratory judgment
coverage action against insured’s subsequent liability
carrier, which had declined to defend and indemnify
insured, even after they had agreed to contribute to
settlement fund that was intended to avert bad faith
claim by insured, given that ‘‘[e]ach party clearly had a
stake in the outcome and their interests were adverse’’);
American Southern Ins. Co. v. Buckley, 748 F. Supp.
2d 610, 619 (E.D. Tex. 2010) (denying motion to dismiss,
for lack of standing, counterclaim seeking declaratory
judgment with respect to coinsurer’s duty to defend
because duty to defend is immediate and presented
‘‘redressable’’ harm as coinsurer ‘‘was injured by the
expenditure of funds for which it has not been reim-
bursed,’’ as declaration may give rise to subrogation or
contribution); Transportation Ins. Co. v. Pennsylvania
Manufacturers’ Assn. Ins. Co., 641 F. Supp. 2d 406,
411–12 (E.D. Pa. 2008) (rejecting claim that commercial
liability insurer lacked standing to bring declaratory
judgment action against its insured’s subsequent carrier
on ground that it ‘‘was neither a party to the [subse-
quent] insurance contract . . . nor an intended third
party beneficiary’’ because ‘‘there is no bar against an
insurer obtaining a share of indemnification or defense
costs from other insurers under other insurance clauses
or under the equitable doctrine of contribution’’ [inter-
nal quotation marks omitted]), rev’d on other grounds,
346 Fed. Appx. 862 (3d Cir. 2009); Fremont Indemnity
Co. v. California National Physician’s Ins. Co., 954 F.
Supp. 1399, 1401 (C.D. Cal. 1997) (‘‘actual controversy
exists between [two medical malpractice insurers] mak-
ing declaratory relief appropriate’’ in dispute about
whether policy required defendant to defend their com-
mon insured); Maryland Ins. Co. v. Attorneys’ Liability
Assurance Society, Ltd., 748 F. Supp. 627, 632 (N.D. Ill.
1990) (insured is not per se necessary party to create
privity between coinsurers in declaratory judgment
action).20
   The cases following United Services Automobile
Assn. v. Royal-Globe Ins. Co., supra, 511 F.2d 1094, are
more persuasive authority than the Provident Life &
Accident Ins. Co. line of cases because they are more
consistent with our state’s existing case law.21 Addition-
ally, these cases are in accord with the classical
aggrievement approach that this court follows when
determining whether a party has standing to bring a
declaratory judgment action. See, e.g., Bysiewicz v.
DiNardo, supra, 298 Conn. 758; Connecticut Busi-
ness & Industry Assn., Inc. v. Commission on Hospi-
tals & Health Care, supra, 218 Conn. 347–48. The
contrasting requirement, imposed by cases such as
Provident Life & Accident Ins. Co., that the insured be
joined for purposes of conferring standing is inconsis-
tent with our own recent case law holding that ‘‘the
failure to give notice to or to join an indispensable party
does not impact the court’s subject matter jurisdiction.’’
Batte-Holmgren v. Commissioner of Public Health, 281
Conn. 277, 288, 914 A.2d 996 (2007); and with local
federal case law standing for the proposition that, in the
Second Circuit, ‘‘in suits between insurers concerning
respective liabilities, the insured is not an indispensable
party,’’ when the ‘‘action . . . is strictly an inter-carrier
dispute over priority of contribution to a settlement.
[The insured’s] interests are fully protected and it is in
no danger of being left uncovered.’’22 Home Ins. Co. v.
Liberty Mutual Ins. Co., 678 F. Supp. 1066, 1070
(S.D.N.Y. 1988), citing Wyoming v. Ins. Co. of North
America, 518 F.2d 23 (2d Cir. 1975); see also Royal Ins.
Co. of America v. Caleb V. Smith & Son, Inc., United
States District Court, Docket No. 3:90CV651 (WWE)
(D. Conn. June 16, 1997) (rejecting argument that ‘‘the
insured is always an indispensable party in a declara-
tory judgment action where the insurance carrier is
contesting its obligation to provide coverage to the
insured’’ [emphasis added]).
   In support of its claim that Travelers lacked standing
to bring this declaratory judgment action, Netherlands
relies on our statement in Wilson v. Kelley, supra, 224
Conn. 116, that ‘‘a declaratory judgment action must
rest on some cause of action that would be cognizable
in a nondeclaratory suit.’’ Netherlands then posits that
Travelers lacked standing because the sole remaining
count of the complaint essentially pleaded breach of
contract between Netherlands and Lombardo, which is
a legal claim; see, e.g., Sovereign Bank v. Licata, 116
Conn. App. 483, 508, 977 A.2d 228 (2009), appeal dis-
missed, 303 Conn. 721, 36 A.3d 662 (2012) (per curiam);
and ‘‘one who [is] neither a party to a contract nor a
contemplated beneficiary thereof cannot sue to enforce
the promises of the contract . . . .’’ (Internal quotation
marks omitted.) Dow & Condon, Inc. v. Brookfield
Development Corp., supra, 266 Conn. 579. We disagree.
Even if the first count of Travelers’ complaint implies
that Netherlands is breaching its contractual duty to
defend Lombardo,23 the quoted portion of Wilson does
not require that the cause of action underlying the
declaratory judgment action be justiciable if brought as
a nondeclaratory suit. Rather, we agree with Travelers’
argument that, consistent with the often prospective
nature of declaratory relief, this phrase is simply a refer-
ence point that is utilized to avoid ‘‘convert[ing] our
declaratory judgment statute and rules into a conve-
nient route for procuring an advisory opinion on moot
or abstract questions . . . .’’ (Citations omitted.) Wil-
son v. Kelley, supra, 116; see also id. (‘‘if a statute of
limitations would have barred a claim asserted in an
action for relief other than a declaratory judgment, then
the same limitation period will bar the same claim
asserted in a declaratory judgment action’’).
   Specifically, the meaning of this aspect of Wilson is
illustrated by our decision in Bysiewicz v. DiNardo,
supra, 298 Conn. 759–60, considering this passage and
concluding that a candidate for the Office of Attorney
General had the requisite standing to seek a declaratory
judgment with respect to whether she had the statutory
qualifications to hold that office. Our conclusion was
grounded by the facts that, should the candidate ulti-
mately be elected, her qualifications could be tested by
a quo warranto action, and our determination that ‘‘her
declared intention to run for the [O]ffice of [A]ttorney
[G]eneral and her particular interest in avoiding the
great effort and expense of running for that office if
her qualifications to serve in that office could be suc-
cessfully challenged upon her election are sufficient to
confer standing on her to bring this action.’’ Id., 760.
In Bysiewicz, a quo warranto action would not have
been justiciable when the declaratory judgment action
was brought—it would not have been ripe because the
candidate had not yet been elected to office, and, the
candidate, of course, would have lacked the requisite
aggrievement to test her own entitlement to office via
that writ. Thus, this phrase from Wilson stands only
for the proposition that a declaratory judgment action
must be supported by sufficient controversy so as to
not amount to an advisory opinion.
   Turning to the facts of this case, the controversy is
real and ongoing, with Travelers’ claim of injury more
than colorable, given the nature of this coverage dispute
and its averment that it ‘‘is bearing more than its fair
share of Lombardo’s defense’’ because of Netherlands’
refusal to contribute to Lombardo’s defense. See New
London County Mutual Ins. Co. v. Nantes, supra, 303
Conn. 749–50. Indeed, the nature of the declaratory
relief sought in the first count of the complaint is ren-
dered nonadvisory by the fact that it implicates several
cognizable causes of action, including a breach of con-
tract action by Lombardo and an action by Travelers
seeking equitable contribution24—causes that are
closely related, despite the fact that one is legal, and
the other equitable, in nature. See Continental Casualty
Co. v. National Union Fire Ins. Co. of Pittsburgh, PA,
940 F. Supp. 2d 898, 918–19 (D. Minn. 2013) (describing
relationship between insurer’s action for equitable con-
tribution and insured’s rights under contract). Accord-
ingly, we conclude that the trial court properly
determined that Travelers had standing to bring this
declaratory judgment action against Netherlands.
                             II
                  COVERAGE CLAIMS
   We next turn to Netherlands’ claim that the trial court
improperly determined that it has a duty to defend
Lombardo under the CGL policies. Specifically, Nether-
lands claims that: (1) the underlying complaint does not
allege an occurrence with resulting property damage
during the relevant policy periods; and (2) the ‘‘known
injury or damage’’ exclusion relieves it of any obligation
to defend.
    Before turning to Netherlands’ specific claims we
note the following general principles governing the
insurer’s duty to defend. Under the well established
‘‘four corners’’ doctrine, ‘‘the duty to defend is broader
than the duty to indemnify. . . . An insurer’s duty to
defend is triggered if at least one allegation of the com-
plaint falls even possibly within the coverage. . . .
Indeed, [i]t is well established . . . that a liability
insurer has a duty to defend its insured in a pending
lawsuit if the pleadings allege a covered occurrence,
even though facts outside the four corners of those
pleadings indicate that the claim may be meritless or
not covered. . . . The obligation of the insurer to
defend does not depend on whether the injured party
will successfully maintain a cause of action against the
insured but on whether he has, in his complaint, stated
facts which bring the injury within the coverage. If the
latter situation prevails, the policy requires the insurer
to defend, irrespective of the insured’s ultimate liability.
. . . In contrast to the duty to defend, the duty to indem-
nify is narrower: while the duty to defend depends only
on the allegations made against the insured, the duty
to indemnify depends upon the facts established at trial
and the theory under which judgment is actually entered
in the case. . . . Thus, the duty to defend is triggered
whenever a complaint alleges facts that potentially
could fall within the scope of coverage . . . .’’25 (Cita-
tions omitted; emphasis omitted; footnote omitted;
internal quotation marks omitted.) Capstone Building
Corp. v. American Motorists Ins. Co., 308 Conn. 760,
805–806, 67 A.3d 961 (2013); see also Hartford Casualty
Ins. Co. v. Litchfield Mutual Fire Ins. Co., 274 Conn.
457, 463, 876 A.2d 1139 (2005); QSP, Inc. v. Aetna Casu-
alty & Surety Co., 256 Conn. 343, 352, 773 A.2d 906
(2001); Keithan v. Massachusetts Bonding & Ins. Co.,
159 Conn. 128, 139, 267 A.2d 660 (1970); Missionaries
of the Co. of Mary, Inc. v. Aetna Casualty & Surety
Co., 155 Conn. 104, 113, 230 A.2d 21 (1967).
   Further, ‘‘[a]n insurance policy is a contract that is
construed to effectuate the intent of the parties as
expressed by their words and purposes. . . . [U]nam-
biguous terms are to be given their plain and ordinary
meaning. . . . As with contracts generally, a provision
in an insurance policy is ambiguous when it is reason-
ably susceptible to more than one reading. . . . The
determination of whether an insurance policy is ambig-
uous is a matter of law for the court to decide. . . .
   ‘‘If the policy is ambiguous, extrinsic evidence may
be introduced to support a particular interpretation.
. . . If the extrinsic evidence presents issues of credi-
bility or a choice among reasonable inferences, the deci-
sion on the intent of the parties is a job for the trier of
fact. . . .
   ‘‘Ordinarily, if an ambiguity arises that cannot be
resolved by examining the parties’ intentions . . . the
ambiguous language should be construed in accordance
with the reasonable expectations of the insured when
he entered into the contract. . . . Courts in such situa-
tions often apply the contra proferentem rule and inter-
pret a policy against the insurer. . . . The contra-
insurer rule does not apply, however, in actions by one
insurer against another.’’ (Citations omitted; internal
quotation marks omitted.) Metropolitan Life Ins. Co.
v. Aetna Casualty & Surety Co., 255 Conn. 295, 305–306,
765 A.2d 891 (2001). ‘‘[B]ecause the proper construction
of a policy of insurance presents a question of law, the
trial court’s interpretation of the policy is subject to
de novo review on appeal.’’ (Internal quotation marks
omitted.) QSP, Inc. v. Aetna Casualty & Surety Co.,
supra, 256 Conn. 352.
  Finally, we note the following relevant policy provi-
sions at issue, contained in the CGL policies that Nether-
lands issued to Lombardo for policy terms commencing
on August 31, 2000 through June, 30, 2001, and renewed
annually thereafter for five years from June 30, 2001
through June 30, 2006:26
  ‘‘Section I—Coverage . . .
  ‘‘1. Insuring Agreement
   ‘‘a. We will pay those sums that the insured becomes
legally obligated to pay as damages because of ‘bodily
injury’ or ‘property damage’ to which this insurance
applies. We will have the right and duty to defend the
insured against any ‘suit’ seeking those damages. How-
ever, we will have no duty to defend the insured against
any ‘suit’ seeking damages for ‘bodily injury’ or ‘prop-
erty damage’ to which this insurance does not apply.
We may, at our discretion, investigate any ‘occurrence’
and settle any claim or ‘suit’ that may result. . . .
                           ***
  ‘‘b. This insurance applies to ‘bodily injury’ and ‘prop-
erty damage’ only if:
   ‘‘(1) The ‘bodily injury’ or ‘property damage’ is caused
by an ‘occurrence’ that takes place in the ‘coverage ter-
ritory’;
  ‘‘(2) The ‘bodily injury’ or ‘property damage’ occurs
during the policy period; and
   ‘‘(3) Prior to the policy period, no insured listed under
Paragraph 1. of Section II—Who Is An Insured and no
‘employee’ authorized by you to give or receive notice
of an ‘occurrence’ or claim, knew that the ‘bodily injury’
or ‘property damage’ had occurred, in whole or in part.
If such a listed insured or authorized ‘employee’ knew,
prior to the policy period, that the ‘bodily injury’ or
‘property damage’ occurred, then any continuation,
change or resumption of such ‘bodily injury’ or ‘property
damage’ during or after the policy period will be deemed
to have been known prior to the policy period.
   ‘‘c. ‘Bodily injury’ or ‘property damage’ which occurs
during the policy period and was not, prior to the policy
period, known to have occurred by any insured listed
under Paragraph 1. of Section II—Who Is An Insured
or any ‘employee’ authorized by you to give or receive
notice of an ‘occurrence’ or claim, includes any continu-
ation, change or resumption of that ‘bodily injury’ or
‘property damage’ after the end of the policy period.
   ‘‘d. ‘Bodily injury’ or ‘property damage’ will be
deemed to have been known to have occurred at the
earliest time when any insured listed under Paragraph
1. of Section II—Who Is An Insured or any ‘employee’
authorized by you to give or receive notice of an ‘occur-
rence’ or claim:
   ‘‘(1) Reports all, or any part, of the ‘bodily injury’ or
‘property damage’ to us or any other insurer;
  ‘‘(2) Receives a written or verbal demand or claim
for damages because of the ‘bodily injury’ or ‘property
damage’; or
   ‘‘(3) Becomes aware by any other means that ‘bodily
injury’ or ‘property damage’ has occurred or has begun
to occur.’’
                             A
Occurrence or Property Damage during Policy Period
   We begin with Netherlands’ claim that the underlying
complaint does not allege an occurrence with resulting
property damage during its policy periods. Netherlands
posits that its ‘‘coverage began over four years after
the construction was completed, and the water intru-
sion and property damage allegedly began. The damage
alleged occurred well before [Netherlands’] coverage
period. Since the alleged damage began and was ongo-
ing and continuous, prior to the inception of Nether-
lands’ . . . policies, the damages alleged are not
covered . . . .’’ Netherlands argues that a reading of
‘‘the [underlying] complaint in its entirety and not just
particular paragraphs in isolation provide the basis for
the analysis of the duty to defend,’’ and that a reading
of the ‘‘general allegations as well as the specific allega-
tions directed at Lombardo’’ demonstrate that the
‘‘property damage manifested prior to the inception of
Netherlands’ . . . policies . . . .’’ Netherlands further
argues that the trial court improperly characterized the
water intrusion over the years following construction,
‘‘seemingly treating each water intrusion as a new
event’’; Netherlands instead contends that the ‘‘water
intrusion, from its first appearance to its last, is the same
occurrence.’’ To this end, Netherlands cites Quanta
Indemnity Co. v. Davis Homes, LLC, 606 F. Supp. 2d
941 (S.D. Ind. 2009), as standing for the proposition
that the ‘‘fact that the property damage progressed and
took different forms over time does not trigger subse-
quent policies.’’
   In response, Travelers contends that the underlying
complaint alleges property damage during the six Neth-
erlands policy periods, from August 31, 2000 to June
30, 2006, insofar as the ‘‘ ‘property damage,’ was caused
by the ‘continuing and progressive’ water intrusion’’
that commenced after January 31, 1996, and was not the
subject of repair work until February 14, 2008. Travelers
cites Peck v. Public Service Mutual Ins. Co., 363 F.
Supp. 2d 137 (D. Conn. 2005), in support of its argument
that courts have ‘‘rejected under Connecticut law the
same ‘occurrence during the policy period’ argument
that Netherlands advances [in this] appeal,’’ and con-
tends that ‘‘Netherlands policies . . . do not require
that the ‘occurrence’ happen during the periods they
cover; they require only that resulting ‘property damage’
occurs during those periods.’’ We agree with Travelers,
and conclude that the underlying complaint alleges
property damage within Netherlands’ policy periods.
   The underlying complaint alleges in relevant part that
‘‘Lombardo, under a prime contract with the state . . .
performed masonry and related services at the [law
library] [p]roject.’’ It then alleges that the law library
‘‘[p]roject was designed starting in 1992 and construc-
tion commenced in 1994, with completion in 1996,’’ and
the ‘‘state began occupying the [law] library on January
31, 1996.’’ Further, ‘‘[d]uring the months and years fol-
lowing completion of the project and occupancy by
the state, the state began to experience problems with
water intrusion into the [law] library. The defendants
[in the underlying action] were given notice of these
problems and frequently visited the [law] library to
ascertain the nature and extent of the problem. During
the project, the defendants [in the underlying action]
had provided written assurances that their work and/
or materials were free from defects, and the state relied
on those assurances. At no point did the defendants [in
the underlying action] disclose that those assurances
were false.’’ The complaint then states that ‘‘[o]ver the
years the water intrusion proved to be continuing and
progressive, to the point that in the 2000s the state
retained forensic engineers to investigate the full extent
and likely causes of the problem.’’ The underlying com-
plaint claimed that a forensic investigation revealed
numerous defects, including ‘‘[i]mproper flashing mate-
rial, design, and installation,’’ ‘‘[i]mproper design and
installation of the windows,’’ and ‘‘[i]mproper design
and installation of the wall anchoring system, such that
the exterior stone facade of the [law] library is not
adequately stabilized and secured,’’ all of which ‘‘have
caused tangible and physical harm to the [law] library
. . . .’’ The state ‘‘retained an engineering firm to design
corrective work, and awarded the contract to perform
that work,’’ which was underway when the state filed
the underlying action in 2008. The state alleged that
‘‘[b]efore completing the design of the corrective work
the state provided copies of design documents and
forensic findings to the defendants [in the underlying
action] and sought their comments and input.’’ From
these facts, the state pleaded claims of breach of con-
tract, negligence, negligent misrepresentation, and
intentional misrepresentation against Lombardo.
   We conclude that the underlying complaint alleges
property damage that triggered Netherlands’ duty to
defend Lombardo. Netherlands’ policies covered peri-
ods from August 31, 2000 until June 30, 2006. Although
the construction of the law library was completed in
1996, the problems began in the ‘‘months and years’’
that followed the state’s occupancy on January 31, 1996,
and the ‘‘water intrusion proved to be continuing and
progressive’’ into the 2000s, when the ‘‘state retained
forensic engineers to investigate the full extent and
likely causes of the problem.’’ Thus, the property dam-
age alleged in the underlying complaint—however
broadly worded—extended into Netherlands’ policy
periods.
   Netherlands argues, however, that ‘‘[a]ll of the water
intrusions constitute one occurrence, which began soon
after January, 1996,’’ and ‘‘all of the property damage
alleged by the state was caused by Lombardo’s alleged
defective construction. The fact that the property dam-
age progressed and took different forms over time does
not trigger subsequent policies.’’ Netherlands’ argu-
ment, however, contradicts the plain and unambiguous
language of the policy, which ‘‘does not require that
the ‘occurrence’ take place within the policy period,
only that the resulting injury or property damage occur
during the policy period.’’ Peck v. Public Service Mutual
Ins. Co., supra, 363 F. Supp. 2d 142; see also id., 142–44
(no coverage under commercial general liability policy
for property damage claim limited to loss of use because
occurrence, namely, continuous exposure to loud music
and vibrations, took place outside policy period, and
policy provided that ‘‘ ‘[a]ll such loss of use shall be
deemed to occur at the time of the ‘‘occurrence’’ that
caused [loss of use]’ ’’ [emphasis omitted]). Indeed, as
we recently decided in interpreting identical CGL policy
language in Capstone Building Corp. v. American
Motorists Ins. Co., supra, 308 Conn. 760, the ‘‘ ‘occur-
rence’ ’’ is the defective work, whereas the ‘‘property
damage’’—in this case water intrusion—results from
that occurrence. See id., 776 (‘‘[W]e conclude that defec-
tive workmanship can give rise to an ‘occurrence’ under
the insuring agreement. This is, however, only the first
step in determining whether the damage at issue . . .
is covered under the policy. The terms of the insuring
agreement require both an ‘occurrence’ and ‘property
damage’ for coverage. We therefore turn to consider
the ‘property damage’ requirement of the insuring
agreement.’’). Accordingly, we conclude that the under-
lying complaint alleges property damage within the peri-
ods of Netherlands’ policies.27
                            B
          ‘‘Known Injury or Damage’’ Clause
   We next address Netherlands’ claim that the ‘‘known
injury or damage’’ exclusion of the CGL policy pre-
cludes coverage because, ‘‘if Lombardo knew the dam-
age to the [law] library had begun in whole or in part
prior to Netherlands’ policy period, Netherlands will
not cover any of the property damage. Since the state
alleges it gave Lombardo notice of the water intrusion
and damage within months of January 31, 1996, it is
clear that Lombardo knew about the property damage
to the [law] library, at least in part, before Netherlands’
coverage began on August 31, 2000.’’ (Emphasis omit-
ted.) Relying on, inter alia, Travelers Casualty & Surety
Co. v. Dormitory Authority, 732 F. Supp. 2d 347
(S.D.N.Y. 2010), and Quanta Indemnity Co. v. Davis
Homes, LLC, supra, 606 F. Supp. 2d 941, Netherlands
argues that the trial court improperly relied on the com-
mon-law known loss doctrine, which is distinct from
the express policy language. In response, Travelers does
not appear to challenge Netherlands’ understanding of
the known injury or damage exclusion of the CGL policy
vis-a-vis the known loss doctrine, but argues that Neth-
erlands improperly reads facts into the underlying com-
plaint in support of its contention that the known injury
or damage exclusion bars coverage. We agree with Trav-
elers, and conclude that, based on the allegations in
the underlying complaint, the known injury or damage
exclusion does not relieve Netherlands of its duty to
defend.
   By way of background, we note that the known loss
doctrine is a common-law rule that derives from the
‘‘implicit requirement read into every liability insurance
policy that coverage will be provided only for fortuitous
losses . . . .’’ 1 B. Ostrager & T. Newman, Handbook
on Insurance Coverage Disputes (16th Ed. 2013)
§ 8.02[a], p. 676; see id., § 8.02, p. 673 (‘‘by definition,
insurance is not available for losses that the policy-
holder knows of, planned, intended, or is aware are
substantially certain to occur’’). ‘‘[T]he known loss doc-
trine embraces the fortuity requirement by precluding
coverage for a loss known to be certain to create a
liability at the time the policy is issued.’’ Id., § 8.02[c],
p. 685. ‘‘[I]n its most simplistic formulation, [the known
loss doctrine] states that one may not insure against
loss of a building after the building has burned down.’’
Steadfast Ins. Co. v. Purdue Frederick Co., Superior
Court, judicial district of Stamford-Norwalk, Complex
Litigation Docket, Docket No. X08-CV-02-0191697-S
(April 11, 2006) (41 Conn. L. Rptr. 183, 184). No appellate
level court in Connecticut has yet applied the common-
law known loss doctrine, nor determined the extent to
which losses are deemed to be ‘‘known’’ prior to the
issuance of coverage.28 See, e.g., Known Litigation
Holdings, LLC v. Navigators Ins. Co., 934 F. Supp. 2d
409, 419–20 (D. Conn. 2013).
   This appeal does not, however, require us to consider
the contours of the common-law known loss doctrine
in Connecticut because, as Netherlands points out, the
‘‘known injury or damage’’ exclusion in the CGL policy
stands in distinction to that common-law principle; the
contractual provision, when it exists, governs indepen-
dently of the common-law rule, although they may have
overlapping effects in certain cases. See, e.g., Travelers
Casualty & Surety Co. v. Dormitory Authority, supra,
732 F. Supp. 2d 362. Thus, a state’s narrow formulation
of the known loss rule; see footnotes 29 and 30 of this
opinion; ‘‘cannot be used to defeat the unambiguous
contrary intent of the parties as reflected in the policy
language itself.’’29 Travelers Casualty & Surety Co. v.
Dormitory Authority, supra, 362; see id., 361–62
(rejecting argument that known injury exclusion
‘‘should be construed in accordance with the known-
risk or known-loss doctrine under New Jersey law,’’
which ‘‘does not bar liability for mere knowledge of
events that might hypothetically or potentially create
liability in the future, but instead, bars coverage only
when the legal liability of the insured is a certainty’’
[emphasis omitted; internal quotation marks omitted]).
   Although the trial court’s analysis improperly con-
flated the common-law known loss doctrine with the
Netherlands policies’ known injury or damage exclu-
sion; see footnote 10 of this opinion; we nevertheless
conclude that it properly determined that the exclusion
does not relieve Netherlands of its duty to defend in
this case. Although the allegations in the underlying
complaint arguably permit a reasonable inference that
Lombardo knew of the property damage in the law
library prior to the inception of its policies with Nether-
lands, unlike in other cases with more detailed factual
records,30 they do not compel that conclusion as a mat-
ter of law, especially given the well established maxim
that, ‘‘[i]f an allegation of the complaint falls even possi-
bly within the coverage, then the insurance company
must defend the insured.’’ (Internal quotation marks
omitted.) Security Ins. Co. of Hartford v. Lumbermens
Mutual Casualty Co., 264 Conn. 688, 712, 826 A.2d 107
(2003). Although paragraph 43 of the underlying com-
plaint avers that the ‘‘defendants were given notice of
these [water intrusion] problems and frequently visited
the [law] library to ascertain the nature and extent of
the problem,’’ those allegations do not specify exactly
when Lombardo received notice, other than to state
that the water problems began ‘‘[d]uring the months
and years’’ following the project’s completion and the
state’s occupancy in January, 1996, and that forensic
engineers were retained in the ‘‘2000s.’’ Similarly, the
underlying complaint does not state when exactly those
engineers’ reports were provided to Lombardo, only
that they were at some point.31 Insofar as Netherlands
was not Lombardo’s only insurer during the eight years
of the 2000s leading up to the state’s filing of the underly-
ing action, and because we construe insurance policies
to afford coverage whenever possible, we conclude that
the trial court properly determined that the facts alleged
in the underlying complaint do not preclude coverage
for purposes of the duty to defend.
                             III
                 ALLOCATION PERIOD
   We next turn to Netherlands’ claim that the trial court
improperly allocated the defense costs over a period
of 144 months. Specifically, Netherlands argues that
this allocation period for determining the insurers’ pro
rata share ‘‘is contradicted by the controlling prece-
dent,’’ namely, the decision of this court in Security
Ins. Co. of Hartford v. Lumbermens Mutual Casualty
Co., supra, 264 Conn. 688, in which, Netherlands con-
tends, we adopted the ‘‘exposure theory of triggering
coverage.’’ Netherlands asserts that, under that theory,
wherein ‘‘the exposure period runs from first injury to
manifestation,’’ the allocation period should have been
no more than twelve months because the injury was
the water intrusion, which manifested less than one
year after the state’s occupancy of the law library on
January 31, 1996. In response, Travelers argues that
Netherlands misreads Security Ins. Co. of Hartford,
and argues that we actually adopted in that decision ‘‘an
‘injury-in-fact trigger,’ under which progressive injuries
that span multiple policy periods trigger all policies in
effect during the progression of the injury,’’ which in
this case was a period of 144 months. We agree with
Travelers, and conclude that, consistent with the ‘‘con-
tinuous trigger’’ situation addressed in Security Ins.
Co. of Hartford, the trial court properly allocated the
insurers’ pro rata shares over a 144 month period.
  In Security Ins. Co. of Hartford, we concluded that
‘‘the pro rata method of allocating defense costs applies
in long latency loss claims that implicate multiple insur-
ance policies’’; Security Ins. Co. of Hartford v. Lum-
bermens Mutual Casualty Co., supra, 264 Conn. 700;
in that case, litigation arising from ‘‘bodily injuries alleg-
edly resulting from the inhalation of asbestos’’ during
a period of time from 1951 through 1996. Id., 691–92.
In applying the pro rata method in Security Ins. Co. of
Hartford, we upheld the trial court’s determination that
the ‘‘asbestos litigation involved a ‘continuous trigger
situation such that all asbestos related injury policies
issued during the extended exposure period have been
triggered for coverage and all companies that issued
such policies are responsible for defense costs related
to the . . . asbestos litigation.’ ’’ Id., 696–97. In describ-
ing this ruling of the trial court, we set forth in a footnote
four theories of the trigger of coverage, namely, ‘‘[m]ani-
festation,’’ ‘‘[e]xposure,’’ ‘‘[i]njury-in-fact or actual
injury,’’ and ‘‘[m]ultiple, [c]ontinuous, or [s]uccessive
trigger.’’32 (Emphasis omitted; internal quotation marks
omitted.) Id., 697 n.12.
   Contrary to Netherlands’ argument, nowhere in Secu-
rity Ins. Co. of Hartford did we adopt the exposure
trigger of coverage.33 Rather, we upheld a pro rata allo-
cation based on the trial court’s unchallenged decision
that the continuous trigger theory applied, thereby
bringing into play all of the insured’s liability policies
over the forty plus year claim period in that case,
expressly holding, without further elaboration, that the
trial court’s allocation therein was ‘‘reasonable . . . .’’
Id., 720 n.17; see also id., 697 n.12 (defining continuous
trigger theory). Indeed, there is no subsequent Connect-
icut authority holding to the contrary. See Steadfast Ins.
Co. v. Purdue Frederick Co., Superior Court, judicial
district of Stamford-Norwalk, Complex Litigation
Docket, Docket No. X08-CV-02-0191697-S (May 18,
2006) (41 Conn. L. Rptr. 604, 608) (noting that trial court
in Security Ins. Co. of Hartford applied continuous
trigger approach and stating that ‘‘[a]lthough the reason
multiple insurance policies are triggered in this case
differs from the reason in Security [Ins. Co. of Hart-
ford], under the reasoning of Security [Ins. Co. of Hart-
ford], the defense cost should be allocated among the
triggered policies and [the insurer] should only be liable
for a pro-rata share of the defense costs of the suits in
which the complaint does not allege a specific date of
injury’’); accord United Technologies Corp. v. Ameri-
can Home Assurance Co., 989 F. Supp. 128, 153 (D.
Conn. 1997) (‘‘[T]he [c]ourt believes that Connecticut
would apply the multiple injury trigger in gradual envi-
ronmental contamination cases. Interpreting the injury-
in-fact approach as having multiple triggers reflects the
reality that one contaminating event can result in sev-
eral different losses after the date of its occurrence.’’).
Accordingly, we see no basis for Netherlands’ argument
that Security Ins. Co. of Hartford holds that Connecti-
cut applies the exposure trigger theory in cases wherein
there is an extended injury implicating multiple policies.
We, therefore, conclude that the trial court properly
determined that the appropriate allocation period was
144 months.
                            IV
              UNCLEAN HANDS CLAIMS
  Finally, we turn to Netherlands’ claims that the trial
court: (1) improperly denied its motion for permission
to amend its answer and special defenses to assert the
special defense of unclean hands; and (2) improperly
precluded it from presenting evidence of Travelers’
unclean hands at trial.
   Before addressing these claims in detail, we note
that the record reveals the following additional relevant
facts and procedural history. On January 24, 2012, less
than two weeks before the trial date of February 2, 2012,
Netherlands filed a request for permission to amend its
answer and special defenses to assert a sixth special
defense, namely, unclean hands. Netherlands repre-
sented that the addition of this special defense was
prompted by Travelers’ disclosure, on December 21,
2011, of supplemental discovery in response to a request
by Lumbermens; see footnotes 1 and 4 of this opinion;
that had alerted Netherlands to previously unknown
facts. In that proposed special defense, Netherlands
averred that this new discovery proves that Travelers
knew that Netherlands did not have a duty to defend
in the underlying case, rendering this declaratory judg-
ment action ‘‘[wilful] misconduct’’ by Travelers, thus
barring its request for equitable relief under the doctrine
of unclean hands.34 In response, Travelers objected to
the motion, contending that Netherlands’ request, made
barely one week before trial, was prejudicially late and
was conclusory because it did not state which docu-
ments, of the nearly 6000 pages of discovery that had
been produced, constituted the newly discovered evi-
dence that supported Netherlands’ late amendment.
Travelers also argued, consistent with its evidentiary
objections at trial,35 that the only evidence relevant to
the dispute before the court, concerning the duty to
defend, was the underlying complaint and Netherlands’
insurance policy.
  During a hearing on the motion, the court and the
parties discussed whether the court needed to rule on
the motion, given Travelers’ withdrawal of the second
count of the complaint seeking equitable subrogation,
discussed in part I of this opinion. Ultimately, counsel
for Netherlands stated that the special defense would
apply to both counts, given that the declaratory judg-
ment count in the complaint alleged injury to Travelers’
legal and equitable rights, and sought remedies under
both theories. Counsel for Netherlands then informed
the court that it had received more than 7000 pages
of documents in December indicating ‘‘that there was
information within the Travelers’ own file that sup-
ported our position that Lombardo knew and when they
knew of this loss. And that becomes relevant because
they’ve come in to here and asked us to contribute to
a defense that they had absolute knowledge . . . that
our policy did not cover . . . for the claims being
made.’’ In response, counsel for Travelers argued that
none of the evidence was relevant under the four cor-
ners rule for determining the duty to defend.36 Ulti-
mately, the trial court denied Netherlands’ motion for
permission to amend the answer and special defenses
to assert the special defense of unclean hands, noting
the age of the case, and that Netherlands’ motion was
not acknowledged on the operative pleadings contained
in the parties’ joint trial management report, filed on
January 26, 2012. Indeed, counsel for Netherlands
acknowledged that this omission was an ‘‘oversight.’’
   Further, in connection with Travelers’ motion to
exclude extrinsic evidence; see footnote 35 of this opin-
ion; and consistent objections, the trial court subse-
quently concluded that, under Connecticut law,
evidence beyond the underlying complaint and the pol-
icy at issue is irrelevant. Accordingly, the trial court
declined to consider any evidence with respect to Lom-
bardo’s knowledge, including sustaining on relevance
grounds Travelers’ objections to Netherlands’ attempts
to elicit testimony about reservation of rights letters
from Travelers to Lombardo in 2003, 2005 and 2006.
                             A
                    Motion to Amend
  Netherlands contends that the trial court abused its
discretion in denying its motion for permission to
amend its answer and special defenses to assert the
special defense of unclean hands. Netherlands claims
that the trial court improperly denied the motion to
amend because it had not received and reviewed the
motion papers before rendering a decision, meaning
that it could not have understood the factual and legal
basis for the motion. Netherlands also contends that
granting this motion would not have prejudiced or sur-
prised Travelers, as presentation of evidence of unclean
hands would not have required additional witnesses
beyond those who testified at the court trial, and the
supporting documentary evidence had already been dis-
closed by Travelers. In response, Travelers contends
that the trial court did not abuse its discretion in denying
Netherlands’ motion because any evidence of unclean
hands was legally irrelevant to the issues before the
court following Travelers’ withdrawal of the second
count of the complaint. Travelers also posits that the
proposed amendment was untimely and would have
worked an injustice, because it was filed less than two
weeks before trial in this case, which had been pending
for more than two years. We agree with Travelers and,
accordingly, conclude that the trial court did not abuse
its discretion by denying Netherlands’ motion for per-
mission to amend the special defenses.
   ‘‘Our standard of review . . . is well settled. While
our courts have been liberal in permitting amendments
. . . this liberality has limitations. Amendments should
be made seasonably. Factors to be considered in pass-
ing on a motion to amend are the length of the delay,
fairness to the opposing parties and the negligence, if
any, of the party offering the amendment. . . . The
motion to amend is addressed to the trial court’s discre-
tion which may be exercised to restrain the amendment
of pleadings so far as necessary to prevent unreasonable
delay of the trial. . . . Whether to allow an amendment
is a matter left to the sound discretion of the trial court.
This court will not disturb a trial court’s ruling on a
proposed amendment unless there has been a clear
abuse of that discretion. . . . It is [Netherlands’] bur-
den in this case to demonstrate that the trial court
clearly abused its discretion.’’ (Internal quotation marks
omitted.) Dow & Condon, Inc. v. Brookfield Develop-
ment Corp., supra, 266 Conn. 583–84; see also Ruggiero
v. Pellicci, 294 Conn. 473, 480–81, 987 A.2d 339 (2010)
(per curiam); Rizzuto v. Davidson Ladders, Inc., 280
Conn. 225, 255, 905 A.2d 1165 (2006). That an amend-
ment would confuse the issues in the case also supports
a trial court’s decision to deny permission to amend a
complaint or special defense. See Rose v. Messier, 1
Conn. App. 563, 565, 474 A.2d 100 (1984).
   We conclude that the trial court did not abuse its
discretion in denying the motion for permission to
amend its pleadings to assert the defense of unclean
hands. First, Netherlands’ argument that the trial court
could not have understood the motion because it ruled
on it without first reviewing the papers is unconvincing.
Although Netherlands accurately observes that,
because of a clerical oversight, the motion initially was
not included in the court’s paper file at the time of trial
in this preelectronic filing case, that lapse did not mean
that the trial court did not review or understand the
motion. The record reveals that the parties provided
the trial court with a courtesy copy of the two page
motion, and the trial court reviewed the parties’ motions
during recesses insofar as they pertained to the eviden-
tiary issue raised by Travelers, in addition to hearing
extensive oral argument with respect to the legal propri-
ety of Netherlands going beyond the pleadings and pol-
icy in attacking its duty to defend.
   Second, the trial court’s denial of the motion was
consistent with its subsequent evidentiary rulings at
trial with respect to the admission of extrinsic evidence
concerning what Lombardo may have known with
respect to the underlying claim. Insofar as Netherlands’
has failed to challenge those rulings properly in this
appeal; see part IV B of this opinion; any relief that we
could grant by concluding the trial court had abused
its discretion in denying the corresponding motion for
permission to amend would be illusory. Accordingly,
we decline to disturb the trial court’s exercise of its
discretion to deny Netherlands’ motion to amend. See
Wallingford v. Glen Valley Associates, Inc., 190 Conn.
158, 162, 459 A.2d 525 (1983) (trial court properly denied
permission to amend defenses that would have
‘‘assert[ed] what the court had disallowed in the coun-
terclaim’’).
                            B
         Evidence concerning Unclean Hands
   Netherlands also contends that the trial court improp-
erly prohibited it from presenting evidence of Travelers’
unclean hands, namely, ‘‘Travelers’ knowledge of the
notice of damage provided to the insured before Nether-
lands’ policy period.’’ Netherlands contends that this
court should extend the rule of Hartford Casualty Ins.
Co., which allows an insurer to ‘‘ ‘be obligated to provide
a defense not only based on the face of the complaint
but also if any facts known to the insurer suggest that
the claim falls within the scope of coverage’ ’’; Hartford
Casualty Ins. Co. v. Litchfield Mutual Fire Ins. Co.,
supra, 274 Conn. 466–67; and hold that, ‘‘when one
insurer is in possession of knowledge that shows a
claim does not fall within another insurer’s coverage,
the carrier should not be permitted to make a claim for
contribution based on a ‘face of the complaint’ argu-
ment.’’ Netherlands posits that such an extension is
consistent with our holding in Hartford Casualty Ins.
Co. that ‘‘the duty to defend derives from the insurer’s
contract with the insured, not from the complaint’’;
(internal quotation marks omitted) Hartford Casualty
Ins. Co. v. Litchfield Mutual Fire Ins. Co., supra, 467;
and argues that ‘‘Travelers should not be permitted to
use a third party’s complaint to create duties that do
not exist under the contract between Netherlands and
Lombardo.’’ In response, Travelers posits that Nether-
lands’ argument suggests an ‘‘illogical and unprece-
dented’’ change in the law that ‘‘suffers [from] the
obvious and fatal flaw of rewarding insurers who
default on their defense obligation and penalizing those
who meet their obligations.’’ Travelers also argues that
we should decline to review Netherlands’ claim because
it is unpreserved. We decline to review this claim
because it is unpreserved.
   ‘‘It is well settled that [o]ur case law and rules of
practice generally limit [an appellate] court’s review to
issues that are distinctly raised at trial. . . . [O]nly in
[the] most exceptional circumstances can and will this
court consider a claim, constitutional or otherwise, that
has not been raised and decided in the trial court. . . .
The reason for the rule is obvious: to permit a party to
raise a claim on appeal that has not been raised at trial—
after it is too late for the trial court or the opposing
party to address the claim—would encourage trial by
ambuscade, which is unfair to both the trial court and
the opposing party.’’ (Citations omitted; internal quota-
tion marks omitted.) Blumberg Associates Worldwide,
Inc. v. Brown & Brown of Connecticut, Inc., 311 Conn.
123, 142, 84 A.3d 840 (2014).
  Netherlands does not, in its main brief or reply brief,
identify where it asked the trial court to adopt the rule
that it advocates on appeal, specific to the context of
suits by insurers against other insurers. Further, our
independent review of the record does not indicate that
this issue was raised before the trial court.37 Accord-
ingly, it is unpreserved and we decline to review it in
this appeal.38
      The judgment is affirmed.
      In this opinion the other justices concurred.
  1
     Also named as defendants in this case were the Peerless Insurance
Company (Peerless) and the Lumbermens Mutual Casualty Company (Lum-
bermens). All claims and cross claims against Lumbermens have been with-
drawn. It has not filed an appearance in this appeal. Further, because
Peerless was an umbrella carrier not obligated to defend Lombardo if Nether-
lands had that obligation, no judgment entered as to Peerless, and its policies
are not at issue in this appeal.
   2
     Netherlands appealed from the judgment of the trial court to the Appel-
late Court, and we transferred the appeal to this court pursuant to General
Statutes § 51-199 (c) and Practice Book § 65-1.
   3
     For a more detailed explanation of the underlying action, see State v.
Lombardo Bros. Mason Contractors, Inc., supra, 307 Conn. 420–22.
   4
     The trial court noted that ‘‘[t]he parties stipulated that Lumbermens . . .
settled with [Travelers] before trial commenced.’’ Accordingly, Lumbermens
is no longer a party to this appeal. See footnote 1 of this opinion.
   5
     We note that Travelers’ complaint seeks relief from Peerless, rather than
Netherlands. Because of the umbrella nature of Peerless’ coverage for the
policy periods at issue, consistent with the parties’ briefs and the trial court’s
decision, we refer to Netherlands instead. Specifically, we need not consider
the Peerless umbrella policies because those policies sit atop the Nether-
lands primary CGL policies; should we conclude that there is a duty to
defend under the primary CGL policies, there is correspondingly no defense
obligation under the umbrella policies. See also footnote 1 of this opinion.
   6
     For the applicable CGL policy language, see the detailed facts set forth
in part II of this opinion.
   7
     The trial court, Hon. Jerry Wagner, judge trial referee, had previously
denied the parties’ cross motions for summary judgment.
   8
     The trial court observed that: ‘‘Netherlands’ coverage began on August
31, 2000, and the state’s [underlying] complaint states that some time in ‘the
2000s’ it retained a forensic engineer to investigate the full extent and likely
causes of the problem. Therefore, Netherlands would be responsible for the
continued water intrusion that occurred from August 31, 2000, onward.’’
   9
     Relying on this court’s explanations of occurrence clauses in CGL policies
as they apply to long spanning latent defects in Security Ins. Co. of Hartford
v. Lumbermens Mutual Casualty Co., 264 Conn. 688, 826 A.2d 107 (2003),
and Metropolitan Life Ins. Co. v. Aetna Casualty & Surety Co., 255 Conn.
295, 765 A.2d 891 (2001), the trial court concluded that ‘‘the occurrence
triggering Netherlands’ policy and duty to defend was the water intrusion
that caused property damage to the law library.’’ The trial court rejected
Netherlands’ argument that the ‘‘occurrence was the negligent construction
that started in 1994 and ended in 1996, before their policy period began in
2000,’’ concluding that the plain and unambiguous language of its policy
demonstrated that ‘‘the water leaking through the masonry and causing
physical injury to the property within constitutes an occurrence.’’
   10
      Given that this case ‘‘include[d] multiple parties with potential liability,
and a loss which occurred over the course of many years,’’ the trial court
rejected Netherlands’ reliance on the common-law known loss doctrine and
the known injury or damage exclusion contained in its CGL policies; see
part II of this opinion; in support of its argument that it ‘‘has no duty to
defend Lombardo because Lombardo was on notice of the damage to the
[law] library, in whole or in part, before Netherlands’ coverage began,’’
based on the notifications from the state to Lombardo and other contractors
about the leaks in the law library. The trial court viewed the policy exclusion
‘‘to be analogous to the ‘known loss’ doctrine,’’ which, under Nationwide
Property & Casualty Ins. Co. v. Greater New York Mutual Ins. Co., Superior
Court, judicial district of New Britain, Docket No. CV-06-5002440-S (August
10, 2009) (48 Conn. L. Rptr. 397, 400), and Peck v. Public Service Mutual
Ins. Co., 363 F. Supp. 2d 137, 145 (D. Conn. 2005), applies only to actual
losses, rather than potential losses.
   11
      General Statutes § 52-29 provides: ‘‘(a) The Superior Court in any action
or proceeding may declare rights and other legal relations on request for
such a declaration, whether or not further relief is or could be claimed. The
declaration shall have the force of a final judgment.
   ‘‘(b) The judges of the Superior Court may make such orders and rules
as they may deem necessary or advisable to carry into effect the provisions
of this section.’’
   12
      See Travelers Property Casualty Co. of America v. Continental Casu-
alty Co., Superior Court, judicial district of New London, Docket No. CV-
08-4008325-S (December 29, 2008) (47 Conn. L. Rptr. 18); Vermont Mutual
Ins. Co. v. Westwood Condominium Assn., Superior Court, judicial district
of Hartford, Docket No. CV-03-0825593-S (March 30, 2005); Steadfast Ins.
Co. v. Purdue Frederick Co., Superior Court, judicial district of Stamford-
Norwalk, Complex Litigation Docket, Docket No. X08-CV-02-0191697-S (June
17, 2003) (35 Conn. L. Rptr. 87).
   13
      Practice Book § 17-55 provides: ‘‘A declaratory judgment action may be
maintained if all of the following conditions have been met:
   ‘‘(1) The party seeking the declaratory judgment has an interest, legal or
equitable, by reason of danger of loss or of uncertainty as to the party’s
rights or other jural relations;
   ‘‘(2) There is an actual bona fide and substantial question or issue in
dispute or substantial uncertainty of legal relations which requires settle-
ment between the parties; and
   ‘‘(3) In the event that there is another form of proceeding that can provide
the party seeking the declaratory judgment immediate redress, the court is
of the opinion that such party should be allowed to proceed with the claim
for declaratory judgment despite the existence of such alternate procedure.’’
   14
      Specifically, counsel for Travelers explained: ‘‘We will withdraw [the
equitable subrogation] count for this reason: In order to demonstrate the
amount of money we’ve spent and the percentage . . . we’re entitled to
[get] back, we would have to put the defense bills in evidence. As yet,
Netherlands has not acknowledged the defense obligation. If we provide
those bills to Netherlands we cannot do it within a privilege; we do not
have a common interest privilege with Netherlands at this point. Those bills
would therefore not necessarily at least be protected from discovery by the
state because we could not provide them within a protection or privilege.
And in order to address that problem and to protect the rights of Lombardo—
this case perhaps coming back to life against Lombardo, no one knows—
we have agreed with Netherlands that rather than seeking a money judgment
if we prevail we will simply ask the court to declare the percentage of
defense costs that Netherlands owes, and if that happens then we will have
a privilege with Netherlands, we will both be defending insurers, we can
provide unredacted copies of the bills to it. And we will, between us, sort
out what 48.6 percent of the bills is. So Travelers is not now seeking a
money judgment; it’s simply seeking a declaration and the reason is just to
avoid the potential problem of having defense bills be in the world in a case
that’s not necessarily resolved.’’
   15
      Specifically, counsel for Netherlands explained that her ‘‘understanding
of that agreement . . . is that . . . we would not be putting in the bills
because—and I totally agree with this . . . there are entries in each billing
entry that may describe something that was done that’s work product,
attorney/client privilege information that it would not be appropriate to
make those documents public and certainly in light of the atmosphere that
we have now with . . . complete transparency and everybody being able
to look at everything in court files and once it became public. So we agreed
that . . . were this court to find that they were entitled to the reimburse-
ment that we would deal with that once they were entitled to their reim-
bursement.’’
   16
      Specifically, the transcript reveals the following colloquy:
   ‘‘The Court: So what I’m hearing you say or what I’m jumping ahead that
you’re going to tell me is that you think that a victory by Travelers on the
first count saying there’s a declaratory judgment that there’s a duty to defend
and that—that I can’t go on on the first count and declare a percent and I
would have to do that under the equitable subrogation count? And your
associate is nodding urgently hoping you’ll see her.
   ‘‘[Netherlands’ Counsel]: I think that’s right, Your Honor. I really hadn’t
thought it through; she probably thought it through more than I have but I
think that’s true.
   ‘‘The Court: Well, that’s interesting.’’
   17
      We note that these competing federal and sister state authorities have
been revealed by our independent research. The authorities contained in
the parties’ briefs are limited to Connecticut Superior Court decisions.
   18
      The dispute between the insurers must, of course, be ripe with respect
to the triggering of their defense or indemnity coverage. See, e.g., Liberty
Mutual Ins. Co. v. Lone Star Industries, Inc., 290 Conn. 767, 814–15, 967
A.2d 1 (2009).
   19
      We note the presence of several federal cases consistent with the reason-
ing of the Eleventh Circuit in Provident Life & Accident Ins. Co. See, e.g.,
Travelers Indemnity Co. v. Standard Accident Ins. Co., 329 F.2d 329, 331–32
(7th Cir. 1964); Liberty Mutual Ins. Co. v. Jotun Paints, Inc., United States
District Court, Docket No. Civ. A. 07-3114 (LMA) (E.D. La. March 25, 2008);
TIG Ins. Co. v. Merryland Childcare & Development Center, Inc., United
States District Court, Docket No. 04-2666 B (DJB) (W.D. Tenn. November
9, 2005); Trinity Universal Ins. Co. v. Turner Funeral Home, Inc., United
States District Court, Docket No. 1:02CV231 (RAE) (E.D. Tenn. December
12, 2003).
   20
      Sister state cases revealed by our research are consistent with United
Services Automobile Assn. v. Royal-Globe Ins. Co., supra, 511 F.2d 1094.
See, e.g., Louisville Fire & Marine Ins. Co. v. St. Paul Fire & Marine Ins.
Co., 252 Ala. 532, 535, 41 So. 2d 585 (1949) (declaratory judgment action
‘‘well filed’’ because ‘‘the policies of the two insurance companies were in
force at the date of the destruction of [the insured’s] property, the status
of the complainant and defendant was that of insurers of the same property
of the same insured against the same hazard and they are each proportion-
ately and severally liable for the loss at the ratio which the amount of
their respective policies bears to the whole insurance covering the property
against the perils involved’’); Miller v. Windsor Ins. Co., 923 S.W.2d 91, 94
(Tex. App. 1996) (reinsurer is ‘‘interested party’’ with standing under state
declaratory judgment act, despite not being party to policy at issue); Moun-
tain West Farm Bureau Mutual Ins. Co. v. Hallmark Ins. Co., 561 P.2d
706, 710–11 (Wyo. 1977) (concluding that insurer may bring declaratory
judgment against another insurer whose policy covered same vehicle, despite
‘‘well settled’’ rule ‘‘ ‘that in no case can a stranger to a contract maintain
an action upon it, or for the breach of it,’ ’’ but concluding that no justiciable
issue exists when plaintiff did not admit its own policy into evidence in
order to demonstrate interest in other insurer’s policy).
   We acknowledge that some sister state decisions hold to the contrary
and support Netherlands’ position in this appeal. See State Farm Mutual
Automobile Ins. Co. v. Astro Leasing, Inc., 194 Ga. App. 515, 517, 390 S.E.2d
885 (1990) (insurer, which had admitted obligation as excess insurer and
defended insured, lacked standing to bring declaratory judgment action
against primary insurer that had refused to defend), cert. denied, Docket
No. S90C0711, 1990 Ga. LEXIS 785 (Ga. April 5, 1990); St. Paul Fire &
Marine Ins. Co. v. Medical Protective Co. of Fort Wayne, Ind., 675 S.W.2d
665, 667 (Mo. App. 1984) (liability insurer lacked standing to bring declara-
tory judgment action seeking declaration that its coverage was excess to
that of defendant because it was not party to defendant’s policy, insured
had not been named, and there was no evidence that insured had asked
defendant to provide coverage); State v. Medical Malpractice Joint Under-
writing Assn., Docket No. 03-0743, 2005 WL 1377493, *2 (R.I. Sup. June 7,
2005) (state lacked standing to bring declaratory judgment action against
private insurer of state employee physician to determine whether carrier
was obligated to defend state in pending action, because it was not party,
named insured or third party beneficiary of that policy). We view these
decisions as contrary to the liberal interpretation that we accord to our
declaratory judgment statute, and the body of federal case law that is consis-
tent with that approach.
   21
      These cases also are consistent with the Superior Court decisions relied
upon by Travelers. See footnote 12 of this opinion. Further, we note our
disagreement with Netherlands’ reliance on Century Indemnity Co. v. North-
east Utilities, supra, Superior Court, Docket No. CV-98-0495496-S, and do
not view that case as indicative of a Superior Court split on this issue.
Century Indemnity Co. is in essence a ripeness decision, rather than one
where the insurer was deemed to lack standing on account of lack of a
contractual relationship with the other insurers in the case. Although the
court, Aurigemma, J., stated that an insurer ‘‘lacks standing to sue to enforce
any obligations created by the insurance contracts between [the insured]
and the other insurers’’; id.; it then acknowledged the insurer’s argument
that it was in fact seeking a declaratory judgment and engaged in a detailed
ripeness analysis, holding that the insurer’s liability to its insured had not
yet been determined, meaning that it did not at that point have a ‘‘legal
interest in insurance coverage provided to [the insured] by the other insurer
defendants. While there may be some future dispute between [the plaintiff
insurer] and the other insurers, none exists now. Therefore, [c]ount [two]
fails to satisfy the statutory prerequisites for a declaratory judgment action
because [the plaintiff insurer] has no current interest and no dispute exists
with respect to the defendant insurers. Practice Book § 17-55.’’ Id.
   22
      Of course, if the insured’s substantive rights and interests may be
affected by the outcome of the declaratory judgment proceeding, due process
concerns require it to be joined as an indispensable party. See, e.g., Batte-
Holmgren v. Commissioner of Public Health, supra, 281 Conn. 289–90.
   23
      We note that the first count of Travelers’ complaint does not use the
term ‘‘breach of contract,’’ or complain of any damages to Lombardo caused
by Netherlands’ failure to defend Lombardo with respect to the underlying
claim. Rather, the complaint focuses on the detriment suffered by Travelers
insofar as it ‘‘is bearing more than its fair share of Lombardo’s defense.’’
   24
      As Netherlands accurately points out, although the second count of the
complaint is titled ‘‘equitable subrogation,’’ the allegations therein more
accurately reflect a cause of action for ‘‘equitable contribution’’ between
insurers, particularly as Travelers’ claim does not appear to place it ‘‘in
the shoes’’ of Lombardo, its insured. See Security Ins. Co. of Hartford v.
Lumbermens Mutual Casualty Co., 264 Conn. 688, 714, 826 A.2d 107 (2003)
(‘‘Contribution is a payment made by each, or by any, of several having a
common interest or liability of his share in the loss suffered, or in the money
necessarily paid by one of the parties in behalf of the others. . . . The right
of action for contribution, which is equitable in origin, arises when, as
between multiple parties jointly bound to pay a sum of money, one party
is compelled to pay the entire sum. That party may then assert a right of
contribution against the others for their proportionate share of the common
obligation. . . . Where more than one insurer has issued policies covering
the same risk, a court of equity will exercise jurisdiction over the entire
controversy to resolve the rights of all the interested parties, particularly
where the issues between the insurers and the insured are similar.’’ [Citation
omitted; emphasis omitted; internal quotation marks omitted.]); see also 1
B. Ostrager & T. Newman, Handbook on Insurance Coverage Disputes (16th
Ed. 2013) § 6.01[b], pp. 466–67 (explaining relationship and differences
between doctrines of contribution and subrogation).
   25
      ‘‘An insurer asserting that a claim is not covered under its policy can
either refuse to defend or it [can] defend under a reservation of its right to
contest coverage under the various avenues which would subsequently be
open to it for that purpose. . . . If the insurer declines to provide its insured
with a defense and is subsequently found to have breached its duty to do
so, it bears the consequences of its decision, including the payment of any
reasonable settlement agreed to by the plaintiff and the insured, and the
costs incurred effectuating the settlement up to the limits of the policy.’’
(Citation omitted; internal quotation marks omitted.) Capstone Building
Corp. v. American Motorists Ins. Co., 308 Conn. 760, 806, 67 A.3d 961 (2013).
   26
      This language is contained in each of the CGL policies that Netherlands
had issued for policy terms August 31, 2000 through June 30, 2001, and
renewed annually thereafter for five years from June 30, 2001 through June
30, 2006. It was an endorsement to the first three policies, and incorporated
in the standard text of the remaining three.
   27
      We disagree with Netherlands’ reliance on Quanta Indemnity Co. v.
Davis Homes, LLC, supra, 606 F. Supp. 2d 941, in support of the proposition
that the ‘‘fact that the property damage progressed and took different forms
over time does not trigger subsequent policies.’’ In holding that there was
no coverage under the commercial general liability policy at issue in Quanta
Indemnity Co., the court did not rely on the progressive nature of the bodily
injury, but rather, on the policy’s ‘‘known loss’’ exclusion. See Quanta
Indemnity Co. v. Davis Homes, LLC, supra, 947–49; see also discussion in
part II B of this opinion.
   28
      ‘‘[C]ourts have utilized varying standards in evaluating whether losses
were ‘known’ at the time coverage was purchased.’’ 1 B. Ostrager & T.
Newman, supra, § 8.02[c], p. 685. Several Superior Court and local federal
district court decisions explain the differences between the various
approaches to the common-law known loss rule. ‘‘In its broadest formulation,
the rule would preclude coverage whenever an injury began prior to the
inception of the insurance policy.’’ Peck v. Public Service Mutual Ins. Co.,
supra, 363 F. Supp. 2d 144–45. These courts have, however, concluded that
we would adopt a narrow version of the known loss doctrine that would
limit it ‘‘to circumstances where the insured was aware of actual losses, not
potential losses prior to purchasing the policy.’’ (Emphasis added; internal
quotation marks omitted.) Known Litigation Holdings, LLC v. Navigators
Ins. Co., supra, 934 F. Supp. 2d 419, citing Peck v. Public Service Mutual
Ins. Co., supra, 145; Nationwide Property & Casualty Ins. Co. v. Greater
New York Mutual Ins. Co., Superior Court, judicial district of New Britain,
Docket No. CV-06-5002440-S (August 10, 2009) (48 Conn. L. Rptr. 397, 400).
   29
      The known injury or damage exclusion is known in the insurance indus-
try as the Montrose endorsement because Insurance Services Office, Inc.,
the association that has developed the standard form commercial general
liability insurance policy used throughout the United States; see, Capstone
Building Corp. v. American Motorists Ins. Co., supra, 308 Conn. 773–74;
promulgated it in response to the California Supreme Court’s narrow applica-
tion of the common-law known loss and loss in progress doctrines in Mon-
trose Chemical Corp. of California v. Admiral Ins. Co., 10 Cal. 4th 645,
693, 913 P.2d 878, 42 Cal. Rptr. 2d 324 (1995), which held, inter alia, that
in the context of commercial general liability insurance, a legally insurable
risk exists so long as ‘‘no legal obligation to pay third party claims has been
established . . . .’’ See, e.g., E. Powell et al., ‘‘The ISO CG 00 57 09 99
‘Montrose’ Endorsement,’’ Independent Insurance Agents of America, Inc.
(July 2000) p. 7 (‘‘[i]f the courts want to remove the ‘known loss’ rule from
the lexicon of insurance contract law, then the insurance industry will have
to explicitly incorporate this principle into their liability contracts, which
is what [Insurance Services Office, Inc.] has attempted to do’’), available
at http://www.cib-online.com/PDFfiles/montrose.pdf (last visited July 15,
2014); C. Stanovich, ‘‘Known Injury or Damage,’’ IRMI Risk & Insurance
(October 2003) (‘‘In their January, 1999 Circular, Insurance Services Office,
Inc. . . . announced that the Montrose case, along with other court deci-
sions, rendered the known loss rule inapplicable to [commercial general
liability],’’ and ‘‘the likelihood of an insured’s liability for such continuing
known injury or damage was not to be considered. [Commercial general
liability] coverage was not to apply [even for defense], despite the fact that
the insured may have no liability and therefore no CGL loss. Thus, the
known loss or loss-in-progress rule was transformed to a known injury or
damage rule.’’), available at http://www.irmi.com/expert/articles/2003/sta-
novich10.aspx (last visited July 15, 2014).
   30
      Some of these cases appear to consider extrinsic evidence, along with
the allegations in the underlying complaint, to determine whether the insured
knew of the property damage at issue for purposes of determining whether
the known injury or damage provision barred coverage. See Tower Ins. Co.
v. Dockside Associates Pier 30 LP, 834 F. Supp. 2d 257, 266–67 (E.D. Pa.
2011) (considering complaint letters to and from insured’s management
about water infiltration into condominiums, produced by insurer, in conclud-
ing that they are ‘‘not . . . entitled to coverage’’); Travelers Casualty &
Surety Co. v. Dormitory Authority, supra, 732 F. Supp. 2d 361 (considering
letters and other undisputed extrinsic evidence of remediation efforts in
holding that, because contractor ‘‘became aware prior to the beginning of
the policy period that damage to the [f]looring [s]ystem had occurred or
had begun to occur, [it] cannot seek coverage for the [f]looring [f]ailure
under the terms of the Ohio [c]asualty [p]olicy’’). This, of course, is inconsis-
tent with our well established four corners approach in assessing an insurer’s
duty to defend. See, e.g., Capstone Building Corp. v. American Motorists
Ins. Co., supra, 308 Conn. 805–806.
   31
      We note that there appears to be some division of authority with respect
to the application of the known injury exclusion when the insured party
was alerted to damage prior to the issuance of the policy, attempted remedial
measures to address the problem, and learned later that those remedial
measures were unsuccessful. Compare Essex Ins. Co. v. H & H Land Devel-
opment Corp., 525 F. Supp. 2d 1344, 1348 (M.D. Ga. 2007) (denying insurer’s
motion for summary judgment because there were genuine issues of material
fact as to whether insured contractor’s knowledge of property damage on
one property was ‘‘sufficient to make [it] aware that property damage was
occurring’’ on properties giving rise to claim, and insured ‘‘had reason to
believe its remedial measures had eliminated the problem of excess runoff’’),
and Desert Mountain Properties Ltd. Partnership v. Liberty Mutual Fire
Ins. Co., 225 Ariz. 194, 207–208, 236 P.3d 421 (App. 2010) (holding sufficient
evidence that insured contractor ‘‘lacked knowledge of the relevant property
damage before the policies began’’ because, although aware of customer
complaints about settling houses due to soil compaction made prior to
policy period, it believed that those complaints had been resolved and ‘‘none
of the complaints led [the insured] to believe there was a wide-scale problem
with improper soil compaction’’), aff’d, 226 Ariz. 419, 250 P.3d 196 (2011),
with Harleysville Mutual Ins. Co. v. Dapper, LLC, United States District
Court, Docket No. 2:09CV794 (TFM) (M.D. Ala. July 21, 2010) (The insurer
had no duty to defend because it ‘‘is undisputed that [the insured] received
notice of the . . . property damage [to an adjacent property] directly from
[its owner] at least two months before the . . . property was added to the
[insurer’s] policies. The fact [the insured] thought his remediation efforts
would resolve the situation does not belie his knowledge of the damage.’’).
Insofar as the allegations in the underlying complaint do not preclude the
imposition of a duty to defend on Netherlands, we need not decide this issue.
   32
      We stated: ‘‘Historically, the [comprehensive general liability] [policy]
has been written on an accident or occurrence basis . . . . According to
the express language of the occurrence basis [comprehensive general liabil-
ity], the insurer is obligated to defend claims and pay for covered bodily
injury . . . where the injury is caused by an occurrence and takes place
during the policy period.
   ‘‘Thus, the occurrence-basis policy is geared to paying claims for losses
that take place during the policy period and result in a policyholder’s legal
liability. This means that the time of the negligent acts causing injury (e.g.,
manufacture of asbestos, failure to warn, dangerous design of a consumer
product) is not determinative of the insurer’s obligation to defend and pay.
Rather, there must be injury from an occurrence during the policy period
to trigger occurrence policy coverage. . . .
   ‘‘Courts have responded to the trigger problem in long latency cases
involving occurrence-basis [comprehensive general liability] coverage with
four definitions of the trigger of coverage:
   ‘‘(1) Manifestation. These courts hold that an injury subject to a claim
occurs when it manifests itself or becomes reasonably capable of diagnosis.
   ‘‘(2) Exposure. These courts hold that a policy is triggered when the
claimant is exposed to the alleged cause of the disease regardless of when
the injury became manifest or capable of diagnosis.
   ‘‘(3) Injury-in-fact or actual injury. These courts hold that the occurrence
giving rise to the third-party claim happens at the time when the body’s
defenses to the cause of the disease have been overwhelmed so that signifi-
cant injury has become inevitable.
   ‘‘(4) Multiple, Continuous, or Successive trigger. Under this approach,
pioneered by the District of Columbia Circuit in the well-known case of
[Keene Corp. v. Ins. Co. of North America, 667 F.2d 1034 (D.C. Cir. 1981),
cert. denied, 455 U.S. 1007, 102 S. Ct. 1644, 71 L. Ed. 2d 875 (1982)] an
occurrence has happened whenever the claimant was exposed to the cause
of the injury, was injured in fact, or the injury became manifest. Conse-
quently, any of these events trigger the applicable insurance policy in force
at the time of the event.’’ (Citation omitted; emphasis in original; internal
quotation marks omitted.) Security Ins. Co. of Hartford v. Lumbermens
Mutual Casualty Co., supra, 264 Conn. 697 n.12.
   33
      As Travelers accurately observes, in addition to the definition set forth
in footnote 12 of that opinion, we mentioned the exposure theory in Security
Ins. Co. of Hartford only insofar as we discussed the ‘‘seminal case setting
forth the pro rata method of allocating defense costs’’; Security Ins. Co. of
Hartford v. Lumbermens Mutual Casualty Co., supra, 264 Conn. 706;
namely, Ins. Co. of North America v. Forty-Eight Insulations, Inc., 633
F.2d 1212 (6th Cir. 1980), cert. denied, 454 U.S. 1109, 102 S. Ct. 686, 70 L.
Ed. 2d 650 (1981), which we observed in passing had adopted the exposure
trigger of coverage. Security Ins. Co. of Hartford v. Lumbermens Mutual
Casualty Co., supra, 707–708. Nowhere in Security Ins. Co. of Hartford,
however, did we endorse the exposure trigger of coverage to the exclusion
of other triggers; our endorsement of Forty-Eight Insulations, Inc., was
limited to that court’s policy reasoning for adopting the pro rata method,
insofar as the application of the exposure trigger in that case had allowed
for a ‘‘ ‘reasonable means of proration’ ’’ because the insured ‘‘ ‘has urged
that indemnity costs can be allocated by the number of years that a worker
inhaled asbestos fibers. By embracing the exposure theory, we have agreed.
There is no reason why this same theory should not apply to defense costs.’ ’’
Security Ins. Co. of Hartford v. Lumbermens Mutual Casualty Co., supra,
708, quoting Ins. Co. of North America v. Forty-Eight Insulations, Inc.,
supra, 1225. Indeed, in the very next paragraph of Security Ins. Co of
Hartford, we endorsed similar policy reasoning that had been embraced by
the New Jersey Supreme Court in its adoption of the pro rata method of
apportioning defense costs in Owens-Illinois, Inc. v. United Ins. Co., 138
N.J. 437, 650 A.2d 974 (1994), a decision that expressly adopted the continu-
ous trigger theory as well. Security Ins. Co. of Hartford v. Lumbermens
Mutual Casualty Co., supra, 708–709.
   34
      Specifically, Netherlands claimed that this evidence demonstrated that
Travelers ‘‘has known that Lombardo received notice of the [law] library
water intrusion and resulting property damage from the [state] in 1998 since
January 3, 2002, at the latest.’’ Netherlands also claimed that ‘‘[Travelers]
knew, prior to bringing the present cause of action that the Netherlands’
policies do not cover property damage that the insured knew about in whole
or in part prior to the inception date of the Netherlands’ policies.’’
   35
      To this end, Travelers also filed a motion to exclude irrelevant evidence,
seeking to bar the admission of extrinsic evidence on the ground that, under
Connecticut law, the only evidence relevant to the trial court’s determination
with respect to Netherlands’ duty to defend is the complaint in the underlying
action and the insurance policies. The trial court deferred ruling on Travelers’
motion until the evidence at issue was offered.
   36
      See footnote 25 of this opinion and the accompanying text.
   37
      Our independent review of the transcript demonstrates that the parties
and the trial court discussed, in response to Travelers’ motion, whether
Connecticut law permits the court to go beyond the four corners of the
complaint in determining whether a duty to defend exists. Netherlands relied
on Keithan v. Massachusetts Bonding & Ins. Co., supra, 159 Conn. 128, in
support of the propriety of that action. That discussion was, however, limited
to the propriety of going beyond a complaint to flesh out broad factual
allegations that potentially implicate an insurer’s duty to defend, with the
trial court agreeing with Travelers that this court’s decision in Keithan is
limited to permitting the court to go beyond the complaint only to establish
whether the person sued was actually an insured under the policy at issue.
See id., 141–42. Nowhere in the transcript or record does Netherlands raise
the insurer specific absolute bar argument it presses on appeal as an exten-
sion of Hartford Casualty Ins. Co. v. Litchfield Mutual Fire Ins. Co., supra,
274 Conn. 466–67.
   38
      Moreover, to the extent that Netherlands frames this claim as an eviden-
tiary issue, its briefing is inadequate insofar as it ‘‘lacks the verbatim state-
ment of the relevant objections and the trial court’s ruling thereon required
pursuant to Practice Book § 67-4 (d) (3) for appeals of evidentiary rulings.
See, e.g., Barry v. Quality Steel Products, Inc., 263 Conn. 424, 447 n.20, 820
A.2d 258 (2003); see also Aspiazu v. Orgera, 205 Conn. 623, 636 n.5, 535
A.2d 338 (1987) (‘[w]hen raising evidentiary issues on appeal, all briefs
should identify clearly what evidence was excluded or admitted, where the
trial counsel objected and preserved his rights and why there was error’).’’
Northeast Ct. Economic Alliance, Inc. v. ATC Partnership, 272 Conn. 14,
51 n.23, 861 A.2d 473 (2004). This is particularly so given Netherlands’
failure to provide transcript citations or some other context for the precise
evidentiary rulings that are subject to challenge. See Florian v. Lenge, 91
Conn. App. 268, 286–87, 880 A.2d 985 (2005) (reviewing claim challenging
restrictions on cross-examination despite ‘‘sparse’’ brief noncompliant with
Practice Book § 67-4 [d] [3] ‘‘[b]ecause the defendant, however, gives some
indication as to what he sought to pursue and cites to relevant portions of
the transcript’’).
