The opinion of the Court was delivered by
In this appeal, we revisit the “continuous trigger” and “pro rata allocation” doctrines we adopted to address complex environmental insurance coverage issues in
Owens-Illinois, Inc. v. United Ins. Co.,
138
N.J.
437,
I
The facts of the case are detailed in the decision of the Appellate Division and are incorporated herein as if more fully set forth. 346
N.J.Super.
167,
Spaulding Composites Company, Inc. (Spaulding) purchased $678 million in comprehensive general liability (CGL) insurance between 1967 and 1984. Nine of those policies were issued by Liberty Mutual Insurance Company (Liberty) during the period from 1976 to 1984. The 1976 policy had a $500,000 limit and the other eight each had a $1 million limit. During those nine years in which Liberty was Spaulding’s primary insurer, Spaulding also *29 purchased excess liability in amounts varying from $23 million to $100 million.
Each of Liberty’s nine CGL policies contained the identical noncumulation clause that provided:
PERSONAL INJURY LIABILITY AND PROPERTY DAMAGE LIABILITY
(A) The limit of liability stated in the schedule as applicable to ‘each occurrence’ is the total limit of the company’s liability for all damages because of personal injury or property damage as a result of any one occurrence.
(C) For the purpose of determining the limit of the company’s liability, all personal injury and property damage arising out of continuous or repeated exposure to substantially the same general conditions shall be construed as arising out of one occurrence.
(D) If the same occurrence gives rise to personal injury or property damage which occurs partly before and partly within the policy period, the ‘each occurrence’ limit and the applicable aggregate limit of this policy shall be reduced by the amount of each payment made by the company with respect to such occurrence under a previous policy of which this policy is a replacement.
[(Emphasis added).]
In 1990, the United States Environmental Protection Agency (EPA) identified Spaulding as a potentially responsible party for disposing of hazardous lead-containing wastes at the Caldwell Trucking Company Superfund Site in Fairfield Township, New Jersey. In 1993, Spaulding declared bankruptcy. In 1994, Caldwell Trucking PRP Group (PRP) and the EPA each filed suit against Spaulding in the United States District Court alleging that Spaulding was responsible for cleanup costs at the Caldwell Trucking Superfund site. PRP initially joined Spaulding and its insurers, including Liberty, as direct defendants in the federal court suit seeking contribution to cover past and future costs of cleaning up the site. The district court dismissed PRP’s claims against Liberty and the excess insurers on the ground that PRP did not have a right to bring a direct cause of action against the insurers. Caldwell Trucking PRP Group v. Spaulding Composites Co., 890 F.Supp. 1247, 1256 (D.N.J.1995).
PRP’s federal action against Spaulding continued, and in 1996 the district court granted PRP partial summary judgment on the issue of Spaulding’s liability for an undetermined amount of the *30 costs incurred by PRP to clean up the Caldwell Trucking Superfund site. Caldwell Trucking PRP Group v. Spaulding Composites Co., Civ. No. 94-3531, 1996 WL 608490, at *14 (D.N.J. Apr.22, 1996). The lone issue that remained in the federal litigation was the amount of damages owed by Spaulding to PRP and the EPA for the site cleanup. In 1999, the district court ordered Spaulding, Liberty, the EPA, and PRP into mediation to decide the amount of coverage Liberty would provide under the CGL policies. That effort proved unsuccessful and was abandoned in late 1999. We were informed at oral argument that judgments of liability have been entered against Spaulding in favor of PRP and the EPA totaling over $13 million, and the matter is now before the Third Circuit Court of Appeals.
In the interim, in 1995, Spaulding began this state court action seeking a declaratory judgment regarding insurance coverage in respect of its share of the defense and remediation costs at the Caldwell Trucking Superfund site. Spaulding moved for summary judgment against its insurers, including Liberty. PRP joined in the motion, which the trial court granted. In ruling, the trial court recognized that
Owens-Illinois
had adopted the continuous trigger theory warranting the treatment of sequential environmental damage as a separate occurrence “within each of the years of a CGL policy.” (quoting
Owens-Illinois, supra,
138
N.J.
at 478,
The Appellate Division granted Liberty’s motion for leave to appeal and reversed the summary judgment in favor of Spaulding and PRP, declaring the non-cumulation clause both clear and effective.
Spaulding Composites Co. v. Liberty Mut. Ins. Co.,
346
N.J.Super.
167, 171,
Spaulding and PRP moved for leave to appeal. Several industrial insureds including GAF, R&F Alloy Wire, and NJC Holdings (collectively, the GAF amici) were granted leave to appear as
amicus curiae,
as was the Complex Insurance Claims Litigation Association. The excess carriers filed protective answers to the motion for leave to appeal, taking no position concerning the enforceability and applicability of the non-cumulation clauses but seeking to preserve their rights to challenge PRP’s characterization of their liability, in this action if the court,
sua sponte,
considered the issue of allocation, which had not been raised below and was not determined by the trial court. In 2002, Spaulding assigned all of its rights to coverage from Liberty and its excess insurers to PRP. We granted PRP’s motion for leave to appeal on March 19, 2002,
Spaulding Composites Co. v. Liberty Mut. Ins. Co.,
171
N.J.
439,
II
To understand the issue in this case, Owens-Illinois and Carter-Wallace require explication.
A.
From 1948 to 1958, Owens-Illinois was the manufacturer of asbestos products including “Kaylo.”
Owens-Illinois, supra,
138
N.J.
at 442-43,
*32
Over the years, the company maintained substantial CGL coverage in primary and excess layers.
Id.
at 443-44,
The CGL policies at issue in
Owens-Illinois
provided coverage for property damage or bodily injury that “occurs” during the policy period.
Id.
at 447,
Our concepts of legal causation were developed in an age of Newtonian physics, not of molecular biology. Were it possible to know when a toxic substance clicks on a switch that alters irrevocably the composition of the body and before which no change has occurred, we might be more confident that occurrence-causing damages had taken place during a particular policy period. The limitations of science in that respect only compound the limitations of law.
Mass-exposure toxic-tort cases have simply exceeded the capacity of conventional models of judicial response.
The overwhelming conclusion of the commentators who have evaluated the result is that ... common-law tort doctrines are ill-suited to the resolution of such injury claims, and that some form of statutorily-authorized compensation *33 procedure is required if the injuries sustained by victims of chemical contamination are to be fairly redressed.
No such procedure has been forthcoming. Hence, courts must adapt common-law doctrines to the peculiar- characteristics of toxic-tort litigation.
[Id.
at 458-59,
We went on to evaluate various theories potentially applicable to an environmental claim including the exposure theory
1
the manifestation theory
2
and the continuous trigger theory, among others.
Id.
at 449-51,
Ultimately, we abandoned as “hopeless” the task of attempting to define the particular point that is the occurrence in the long-tail injury process. Rebecca M. Bratspies,
Splitting the Baby: Apportioning Environmental Liability Among Triggered Insurance Policies,
1999
BYU L.Rev.
1215, 1230 (1999). Taking our cue from the seminal decision of
Keene Corp. v. Insurance Co. of N. Am.,
*33 [W]hen progressive indivisible injury or damage results from exposure to injurious conditions for which civil liability may be imposed, courts may reasonably treat the progressive injury or damage as an occurrence within each of the years of a CGL policy. That is the continuous-trigger theory for activating the insurers’ obligation to respond under the policies.
[Owens-Illinois, supra, 138 N.J. at 478-79,650 A.2d 974 .]
*35 Concerning the methodology for dividing responsibility among multiple triggered policies, we unequivocally recognized the conjunction between the continuous trigger and how allocation ultimately would take place:
[W]e believe that common-law resolution of the trigger-of-eoverage issue requires that we consider, .at the same time, the issue of scope of coverage if a policy is triggered. “[T]he choice of trigger theory is related to the method a court will choose to allocate damages between insurers.”
LId. at 459,650 A.2d 974 (citing Northern States Power Co. v. Fidelity & Cas. Co. of N.Y.,523 N.W.2d 657 , 662 (Minn.1994)).]
We went on to explore various approaches including joint and several and pro rata allocation. Diverging from Keene,
[w]e rejected joint-and-several allocation, [Owens-Illinois, supra,] 138 N.J. at 468,650 A.2d 974 , a theory under which the problem of indivisible injury is resolved simply by collapsing the continuous injury into one year. Joint-and-several allocation effectively allows a policyholder to simply select one triggered year and exhaust the coverage provided during that period in satisfaction of its claim, id. at 459-62,650 A.2d 974 , requiring the insurers to sue each other for contribution. We determined that such an approach rested on an assumption not in accordance with the development of the law: “that at every point in the progression the provable damages due to injury in any one of the years from exposure to manifestation will be substantially the same____” Id. at 468,650 A.2d 974 . We also considered the effect on the allocation issue of “other insurance” clauses, which are provisions typically designed to preclude a double recovery when multiple, concurrent policies provide coverage for a loss. We determined that such clauses were not generally applicable in the continuous-trigger context where successive rather than concurrent policies were at issue. Id. at 470,650 A.2d 974 . In sum, we found the contract language and the traditional rules of interpretation to be unhelpful in settling on the proper method of allocating responsibility. Id at 468-71,650 A.2d 974 .
Rather, our resolution of the issue was guided by our concern for the efficient use of resources to address the problem of environmental disease and by the demands of simple justice. Id. at 472-73,650 A.2d 974 .
[Carter-Wallace, supra, 154 N.J. at 321-22,712 A.2d 1116 .]
Instead, we adopted what is called a pro-ration by years and limits method of allocation. We stated that
“any allocation should be in proportion to the degree of the risks transferred or retained during the years of exposure,” and concluded that the “better formula” was to “allocate! ] the losses among the carriers on the basis of the extent of the *36 risk assumed, i.e., proration on the basis of policy limits, multiplied by years of coverage.”
[Carter-Wallace, supra, 154 N.J. at 322,712 A.2d 1116 (citing Owens-Illinois, supra, 138 N.J. at 475,650 A.2d 974 (citing Armstrong World Indus., Inc. v. Aetna Cas. & Sur. Co., 20 Cal.App.4th 296,26 Cal.Rptr.2d 35 , 57 (1993))).]
Put another way,
[t]he basis of an individual insurer’s liability is the aggregate coverage it underwrote during the period in which the loss occurred. Basically, a given insurer’s liability is determined by comparing its particular exposure to the total amount of exposure assumed by all carriers of the triggered policies. This comparison yields a percentage that is then applied to the amount of loss the policyholder sustained.
[Thomas M. Jones & Jon D. Hurwitz, An Introduction to Insurance Allocation Issues in Multiple-Trigger Cases, 10 Vill. Envtl. L.J. 25, 44-45 (1999).]
Under that scheme, the insured is required to pay its “aliquot” share of both defense and indemnification on account of years in which it was uninsured, self-insured, or its coverage was exhausted or bankrupt. Erickson, supra, 28 Brief at 20.
Ultimately, we declared that our choice of the pro-rata allocation method was rooted in the policy considerations that we identified: (1) maximizing resources to cope with environmental injury or damage; (2) giving the greatest incentive to insureds to acquire insurance; and (3) notions of simple justice.
Owens-Illinois, supra,
138
N.J.
at 472-73,
B.
Thereafter, in
Carter-Wallace,
in a case involving the results of pharmaceutical waste disposal, we were faced with the question of how the responsibility of primary and excess insurers
4
is measured in the context of environmental damage over many years
*37
with a continuous trigger of liability. 154
N.J.
at 317,
We reaffirmed the continuous trigger principle and held, as we had in
Owens-Illinois,
that the contract language in the CGL policy and traditional rules of insurance policy interpretation were inadequate to determine the proper method of allocation among primary, first and second level excess insurers.
Id.
at 325,
The second level excess policy that was at issue in
Carter-Wallace
provided $1 million in coverage in excess of $5.1 million in underlying primary and first layer excess coverage.
Id.
at 319,
Although there was nothing unclear about that provision, we rejected the excess insurers’ horizontal exhaustion theory that stated that all primary and first layer excess policies in effect throughout the seventeen-year trigger period had to be exhausted prior to any second layer excess liability attaching.
Id.
at 324,
Instead, we opted for an allocation method we characterized as “more faithful” to the principles articulated in
Owens-Illinois.
Ibid. Citing
Chemical Leaman Tank Lines v. Aetna Cas. & Sur. Co.,
978
F.Supp.
589 (D.N.J.1997),
rev’d on o.g.,
177
F.3d
210 (3d Cir.1999), we adopted a vertical loss allocation by year.
Carter-Wallace, supra,
154
N.J.
at 326-27,
Echoing the policy considerations relied on in Owens-Illinois, we stated:
[T]his approach makes efficient use of available resources because it neither minimizes nor maximizes the liability of either primary or excess insurance, thereby promoting cost efficiency by spreading costs. That method also promotes simple justice, by respecting the distinction between primary and excess insurance while not permitting excess insurers unfairly to avoid coverage in long-term, continuous-trigger cases. Additionally, adoption of that allocation method will introduce a degree of certainty and predictability into the complex world of environmental insurance litigation in continuous-trigger cases.
[W]e anticipate that the principles of Owens-Illinois, as clarified by our decision today, represent the presumptive rule for resolving the allocation issue among primary and excess insurers in continuous trigger liability cases unless exceptional circumstances dictate application of a different standard.
[Carter-Wallace, supra, 154 N.J. at 327-28,712 A.2d 1116 (internal citations and quotation marks omitted).]
See also Quincy Mut. Fire Ins. Co. v. Borough of Bellmawr,
172
N.J.
409, 419,
*39 III
PRP argues that the Appellate Division erred in enforcing the non-cumulation clause because it is inapplicable when a separate occurrence takes place in each year of successive CGL policies, because it is an invalid other-insurance or escape clause, and because it effectively circumvents the continuous trigger and allocation model adopted in Owens-Illinois.
The GAF amici echo that argument, contending that the allocation methodology established in Owens-Illinois and Carter-Wallace is incompatible with Liberty’s non-cumulation clause and that the policy interests underpinning those decisions would be undermined if insurers could contract away their risk through like clauses.
Liberty counters that the Appellate Division’s decision does not disturb either Owens-Illinois or Carter-Wallace, that the claim against Spaulding derived from a single occurrence thus reducing Liberty’s liability to a single year of coverage, and that other courts have found similarly worded non-cumulation clauses unambiguous and enforceable.
The Complex Claims Litigation Association amicus sides with Liberty and argues in favor of the Appellate Division decision. In essence, it urges enforcement of what it characterizes as an unambiguous non-cumulation clause in order to give the insurer and the policyholder “what they bargained for.”
IV
As scholars and treatise writers, without exception, have concluded, Owens-Illinois was a “watershed” in the cripplingly complex area of long-tail environmental exposure insurance coverage. Erickson, supra, 28 Brief at 20; see Jones & Hurwitz, supra, 10 Vill. Envtl. L.J. at 45 (Owens-Illinois is “seminal” case adopting “pro-ration by years and limits”); Barbara Hopkinson Kelly & Colin P. Hackett, Environmental Insurance Coverage Claims and Litigation: Trends and Emerging Coverage Issues, 718 PLI/ *40 Comm 99, 123 (PLI Comm. Law & Practice Course Handbook Series No. AF4477, May-June 1995) (stating that Owens-Illinois decision is “significant” and should be persuasive authority in other jurisdictions addressing environmental contamination cases involving trigger and allocation issues); Michael A. Orlando et ah, Recent Developments in Insurance Coverage Litigation, 34 Tort & Ins. L.J., 481, 498 (1999) (Owens-Illinois regarded as “landmark” decision).
What made Owens-Illinois so important is that it looked beyond contract language and traditional rules of insurance policy interpretation to develop a fair and uniform methodology for addressing complex environmental insurance coverage issues. Bratspies, supra, 1999 BYU L.Rev. at 1236; Erickson, supra, 28 Brief at 21; Garrett G. Gillespie, Note, The Allocation of Coverage Responsibility Among Multiple Triggered Commercial General Liability Policies in Environmental Cases: Life After Owens-Illinois, 15 Va. Envtl. L.J. 525, 550-52 (1996). Specific policy goals are at the heart of that methodology, including maximization of resources available for environmental cleanup; creating incentives for the purchase of insurance; and notions of simple justice. Barry R. Ostrager & Thomas R. Newman, Handbook on Ins. Coverage Disputes § 9.04 (9th ed.1998); Erickson, supra, 28 Brief at 21; Jones & Hurwitz, supra, 10 Vill. Envtl. L.J. at 45-46; Joren S. Bass, Note, The Montrose Decision and Long-Tail Environmental Liability: A New Approach to Allocating Risk Among Multiple Third-Party Insurers, 5 Hastings W.Nw. J. Envtl. L. & Pol’y 209, 220 (1999); Gillespie, supra, 15 Va. Envtl. L.J. at 573-77 (1996).
To achieve those goals, Owens-Illinois declared that long-tail environmental exposure injury and damage would no longer be treated as one continuous occurrence, giving rise to joint and several liability by each insurer up to the full limit of its policy (with the policyholder or injured party choosing which year’s policy would pay all the damages), but would be treated as one occurrence per year triggering all applicable policies, allocated pro
*41
rata, based on the degree of risk assumed.
Owens-Illinois, supra,
138
N.J.
at 478-79,
As legal writers have recognized, it is obvious that
Owens-Illinois
did not simply provide an interim measure calculated to fill in an ambiguous policy provision. Indeed, we noted that the policies were not ambiguous.
Owens-Illinois,
138
N.J.
at 457,
[I]n Owens-Illinois, the New Jersey Supreme Court overturned well established New Jersey law____[T]he court took an issue that had been addressed by many courts around the country and forged a wholly new answer____[T]he court ignored traditional rules of insurance policy construction founded on contra [proferentum] and based its holding on considerations of public policy.
[Gillespie, supra, 15 Va, Envtl. L.J. at 573 (quoting Robert B. Chesler & David A. Thomas, New Jersey Insurance Law After Signo, Morton, Gilbert Spruance, and Owens-Illinois, 9 Mealey’s Litig. Rep. 18,24 (Mealey ed.1995)).]
In a word,
Owens-Illinois
eliminated reliance on particular contract language (other than limits and exclusions) and on traditional rules of interpretation, and set forth a uniform standard for resolving allocation issues in long-tail environmental exposure
*42
cases.
See Carter-Wallace, supra,
154
N.J.
at 328,
V
The question presented is whether the non-cumulation clause in Liberty’s CGL policies can be enforced consonant with the rules we adopted in Owens-Illinois and affirmed in Carter-Wallace. The answer is that it cannot.
Importantly, that outcome is not dependent on technical characterizations of the non-cumulation clause. To be sure, PRP’s argument that the non-cumulation clause is an invalid other-insurance clause under
Owens-Illinois
overreads that case and was rejected properly by the Appellate Division.
Spaulding Composites, supra,
346
N.J.Super.
at 179-80,
The Appellate Division likewise rejected PRP’s further argument that the non-cumulation clause is an invalid escape clause.
Id.
at 179-80,
As we have indicated, the outcome of this case does not depend on a technical characterization of Liberty’s non-cumulation clause, but on the nature of the clause itself. As all parties agree, a noncumulation clause generally, and Liberty’s in particular, operates *44 to limit an insurer’s liability under multiple sequential CGL policies where losses related to a “single occurrence” trigger the successive policies. At the heart of a non-cumulation clause is the notion of a “single occurrence” with multiple year effects. Underlying that notion is the “single occurrence” language of the clause that states that damage “arising out of continuous or repeated exposure to substantially the same general conditions shall be construed as arising out of one occurrence.” What the noncumulation clause seeks to avoid is the “cumulation” of insurance policy limits when only one insured act or “occurrence” is involved. Owens-Illinois clearly rejected the idea that in an environmental exposure case, successive policies are triggered by a “single” occurrence. As Judge Brotman underscored in Chemical Leaman, supra,
[t]he New Jersey Supreme Court in Owens-Illinois held that under the continuous trigger theory it was propounding, progressive indivisible property damage should be treated as an occurrence within each of the years of a CGL policy. On its face, this language appears to direct treatment of progressive property damage as distinct occurrences triggering per-occurrenee limits in each year of a policy. [978 F.Supp. at 607 (internal citations and quotation marks omitted) (emphasis added).]
So viewed, the “single occurrence” language does not implicate “cumulation” of policy limits for damage arising out of a single occurrence and is therefore inapplicable by its own terms.
But even if the non-cumulation clause was not facially inapplicable, we would not enforce it because it would thwart the
Owens-Illinois
pro-rata allocation modality. Once the court turns to pro rata allocation, it makes sense that the non-cumulation clause, which would allow the insurer to avoid its fair share of responsibility, drops out of the policy. Indeed, that is the holding of
Outboard Marine Corp. v. Liberty Mut. Ins. Co.,
283
Ill.App.3d
630, 219
Ill.Dec.
62,
There, the insured, Outboard Marine Corporation (OMC), sought a declaratory judgment that its CGL insurer was obligated to defend it against a suit by governmental agencies concerning *45 water pollution over a period of years. Id. at 745. One of OMC’s excess insurers, the Home Insurance Company (Home), claimed that its maximum liability to OMC was $2 million because of a non-cumulation clause in Home’s policies that otherwise stated that its maximum liability was $3 and $5 million respectively. Id. at 746. After applying the continuous trigger theory to the case and determining that each excess insurer would be liable to OMC based on a pro-rata-time-on-the-risk basis, id. at 749-50, the court held the non-cumulation clause unenforceable, stressing that its application would thwart the pro-rata methodology, “would give the insurers a double credit and would deprive the insured of the full value of its premium.” Id. at 750.
That analysis is wholly congruent with our own. The pro-rata sharing methodology has, at its core, a public policy that favors maximizing, in a fair and just manner, insurance coverage for cleanup of environmental disasters. By applying the non-cumulation clause, insurers who were actually “on the risk” would be insulated from their fair share of liability in direct contravention of Owens-Illinois. See 15 Couch supra. § 220:30 (3d ed. 1999) (“Once a court has determined that a loss is to be shared among sequential insurers on a pro rata basis, ‘prior insurance’ and ‘non-cumulation of liability’ clauses in the policies become unenforceable. ”).
We note that none of the cases cited as support for the enforceability of a non-cumulation clause by Liberty and its
amicus
involves application of the continuous trigger and pro-rata allocation methodology of
Owens-Illinois. See, e.g., Dickies Indus. Servs., Inc. v. Liberty Mut. Ins. Co.,
CA No. 1:97-CV-1391-WBH at *3 (N.D.Ga., Aug. 29, 2000) (deciding case prior to federal district court’s “educated guess” that manifestation trigger would ultimately be rejected by Georgia courts in favor of continuous coverage trigger);
Endicott Johnson Corp. v. Liberty Mut. Ins. Co.,
928
F.Supp.
176, 181 (N.D.N.Y.1996) (applying injury-in-fact trigger — where coverage triggered if actual injury takes place during policy period),
appeal dismissed,
VI
Our sole determination in this case is that Liberty’s noncumulation clause is unenforceable under Owens-Illinois. We take no position on the number of occurrences, the actual allocation of responsibility as between carriers, or any other issue except to reaffirm the vitality of the Owens-Illinois approach and our commitment to its uniform application.
VII
The judgment of the Appellate Division is reversed. The trial court’s grant of summary judgment on the non-cumulation clause in favor of PRP is reinstated.
For reversing — Chief Justice PORITZ and Justices COLEMAN, LONG, VERNIERO, LaVECCHIA, ZAZZALI and ALBIN — 7.
Opposed — None.
Notes
The exposure theory holds that the date of occurrence is that on which the injury-producing agent first contacts the body.
Insurance Co. of N. Am. v. Forty-Eight Insulations, Inc.,
The manifestation theory provides that injury resulting from environmental exposure does not occur until the disease manifests itself.
Eagle-Picher Indus. v. Liberty Mut. Ins. Co.,
See Lincoln Elec. Co. v. St. Paul Fire & Marine Ins. Co.,
Primary insurance provides first dollar liability coverage up to the limits of the insurance contract, usually subject to a deductible. It potentially attaches upon the happening of an insured liability. Scott M. Seaman & Charlene Kittredge, Excess Liability Insurance: Law and Litigation, 32 Tort & Ins. L.J. 653, 655 (1997). Excess insurance is secondary coverage that ordinarily attaches only after a predetermined amount of primary insurance or self-insured retention has been exhausted. Id. at 656.
