A judge of the United States District Court for the District of Massachusetts has certified questions of law to us, pursuant to S.J.C. Rule 1:03,
The background for the certification of the questions of law appears in
In re Acushnet River & New Bedford Harbor: Proceedings re Alleged PCB Pollution,
1. In Belleville’s comprehensive general liability insurance policy, Lumbermen’s agreed, among other things and subject to certain exclusions and exceptions, to provide coverage for liability due to property damage caused by an occurrence. An “occurrence” is defined in the policy as “an accident . . . which results in . . . property damage neither expected nor intended from the standpoint of the insured.” For the purposes of this case, the judge and the parties have assumed that the State and Federal governments, in their underlying claims, seek to recover for property damage caused by an occurrence.
Our focus has been directed to exclusion (f), the so-called pollution exclusion clause, which states that no insurance applies to property damage “arising out of the discharge, dispersal, release or escape of smoke, vapors, soot, fumes, acids, alkalis, toxic chemicals, liquids or gases, waste materials or *678 other irritants, contaminants or pollutants into or upon land, the atmosphere or any water course or body of water; but this exclusion does not apply if such discharge, dispersal, release or escape is sudden and accidentar (emphasis supplied). In this case, Belleville argues that the exclusion does not apply to deny coverage because the releases of pollutants at issue in the underlying case were both “sudden and accidental” within the meaning of those words in the Lumbermens policy.
The certifying judge recognized that there is no unanimity of opinion, even within Massachusetts, concerning the proper interpretation of the “sudden and accidental” exception to the pollution exclusion clause.
Acushnet River,
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Although the certifying judge announced his construction of the exception in the pollution exclusion clause, he certified to us three questions concerning that issue: “(a) Is the word ‘sudden’ as appearing in the pollution exclusion clauses at issue in this case unambiguous? (b) If the answer to question (a) above is yes, does that term have a temporal quality? (c) If the answer to question (b) above is yes, what considerations. ought this Court employ in determining which events qualify as ‘sudden’?”
Acushnet River,
The sudden event to which the exception in the pollution exclusion clause applies concerns neither the cause of the release of a pollutant nor the damage caused by the release. It is the release of pollutants itself that must have occurred suddenly, if the exception is to apply so as to provide coverage. The exception thus focuses on the circumstances of the release. In deciding whether there was an occurrence, on the other hand, the focus of the inquiry is on the property damage, asking whether it was expected or intended from the insured’s point of view. Courts that have failed to appreciate this distinction have led themselves to identify an ambiguity in the policy language that does not exist. See
American Motorists Ins. Co.
v.
General Host Corp.,
We dealt with the words “sudden and accidental” in an insurance policy in
New England Gas & Elec. Ass’n
v.
Ocean Accident
&
Guar. Corp.,
For the word “sudden” to have any significant purpose, and not to be surplusage when used generally in conjunction with the word “accidental,” it must have a temporal aspect to its meaning, and not just the sense of something unexpected. We hold, therefore, that when used in describing a release of pollutants, “sudden” in conjunction with “accidental” has a temporal element. The issue is whether the release was sudden. The alternative is that it was gradual. If the release was abrupt and also accidental, there is coverage for an occurrence arising out of the discharge of pollutants.
We answer the first two portions of the first question as follows: (a) the word “sudden” in the context of the pollution exclusion clause is unambiguous and (b) it has a temporal quality. This is the conclusion of the better reasoned, and particularly the more recent, judicial interpretations of the pollution exclusion clause that appears in the standard comprehensive general liability policy. 4 There are many opinions *681 reaching a contrary conclusion, the reasoning of which is criticized in many of the opinions just cited. 5 If the word “sudden” is to have any meaning or value in the exception to the pollution exclusion clause, only an abrupt discharge or release of pollutants falls within the exception.
The facts concerning the discharge of pollutants by Belle-ville have not been certified to us. Dealing with the certified questions in the abstract, we have said all that we can concerning the considerations that the judge should “employ in determining which events qualify as ‘sudden.’ ” Surely, the abruptness of the commencement of the release or discharge of the pollutant is the crucial element. 6 Our certification rule calls for the presentation of the facts on which the certified question of law is based. See S.J.C. Rule 1:03, § 3 (2). We do not know enough about what the pollution was, and when *682 and how the release or discharge started, to say anything further.
We acknowledge that, in answering the first set of questions certified to us, we are rejecting the contrary holding in
Shapiro
v.
Public Serv. Mut. Ins. Co.,
Because the word “sudden” in the pollution exclusion clause is not ambiguous, we have no need to consider the drafting history of that clause or any statements made by insurance company representatives concerning the intention of its drafters. There is no evidence in the record that Belle-ville relied on or was even aware of any of this background information when it purchased coverage from Lumbermens. The use of such information to resolve an ambiguity in Belle-ville’s insurance policies would have nothing to do with contract negotiations, and thus its use would be different from the use of parol evidence to aid in resolving an ambiguity in a contract. Attempts to use the drafting history and official comments about the purpose of a provision in an insurance policy seem somewhat analogous to attempts to use legislative history in construing an ambiguous statute.
This court has not indicated the extent to which it is appropriate to use the drafting history of a provision in a standard form of insurance policy to resolve a dispute over the meaning of policy language. A formally published, explanatory report of an industry-wide committee that drafted particular policy language would appear likely to be a reliable source for resolving a policy ambiguity. Language changes from one standard policy form to the next would perhaps be instructive. See
Ratner
v.
Canadian Universal Ins. Co.,
359
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Mass. 375, 380 (1971). We have not considered, however, whether statements made after the adoption of standard language may properly be considered or whether the views of one insurance executive may properly be used to guide the interpretation of a standard form of policy used by many companies. Additionally, we have not decided whether the drafting history and other possibly instructive material must be included in the record on appeal and thus have been presented in a manner that would permit countervailing or explanatory material to be submitted in response. See
Eagle-Picher Indus., Inc.
v.
Liberty Mut. Ins. Co.,
2. The second certified question asks whether, under the common law of the Commonwealth, there is any procedure by which an insurer, with a duty to defend but with apparently only a negligible duty to indemnify, can terminate its duty to defend short of conclusively establishing the extent of the underlying claim in circumstances binding on the underlying claimant. The judge points to the opinion authored by Justice Kaplan in
Sterilite Corp.
v.
Continental Casualty Co.,
Lumbermens makes no attempt to describe to us a common law procedure under which its duty to defend could be terminated conclusively without the entry of an order binding on the governmental claimants in this case. Lumbermens argues that, under Fed. R. Civ. P. 19, the underlying claimants are not necessary parties to a declaratory judgment action
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brought against an insured to determine insurance coverage rights. Further, Lumbermens argues that, because the governmental claimants opposed efforts to place them in a procedural posture in which they could be conclusively bound, they should either be deemed not to be necessary parties or to have waived any requirement that they be conclusively bound by any declaration of rights. Finally, citing
Burlington N. R.R.
v.
Woods,
Each of. these arguments concerns an issue that Lumbermens could have raised, and indeed may have raised, with the Federal judge. None of them concerns a question of State law. Our rule authorizing certified questions from other courts relates solely to questions of Massachusetts law. We do not offer our gratuitous services to opine on questions of Federal law. In any event, the judge did not ask us about these issues of Federal law. He has asked us if there is a common law procedure for conclusively cutting short an insurer’s duty to defend in which the underlying plaintiff would not be bound by the determination. In circumstances in which the party to be benefited by a particular answer does not argue the point to us, we feel no heavy burden to answer a certified question in detail. We abstain from speculating on why a declaratory judgment proceeding involving all concerned entities was not maintained in the Federal court.
A declaratory judgment in an action provides an appropriate means of deciding a dispute concerning the meaning of language in an insurance policy. See Boston Symphony Orchestra, Inc. v. Commercial Union Ins. Co., 406 Mass, 7, 15-16 (1989). The problem becomes more complicated when the dispute between insurer and insured involves, not the construction of policy terms, but rather whether, in light of the allegations in a particular complaint, the insurer has a duty to defend. It is that issue that is discussed so thought *686 fully in the Sterilite Corp. opinion. The need to have the underlying claimant bound by any judicial declaration concerning the insurer’s duty to defend does not exist because the underlying claimant would be a necessary party to the action (a matter on which we express no opinion). Rather, that need exists because, until there is an unalterable determination as to the nature of the underlying claim, any declaration of rights concerning the insurer’s duty to defend cannot be conclusive. Although our answer (that a declaratory judgment proceeding under G. L. c. 231A [1988 ed.] provides a “procedure” for definitively resolving a “duty to defend” dispute) does not identify a common law procedure (as to which the judge inquired), it appears to be the only procedure clearly available in all circumstances.
We do not discount the possibility of an action solely between an insurer and an insured concerning the insurer’s duty to defend, where the complaint in the underlying action is so general as to allege a claim arguably falling within the coverage of the policy, but it is apparent from the event that gave rise to the underlying claim that the loss is not covered by the insurance policy. See, e.g.,
Atlantic Mut. Fire Ins. Co.
v.
Cook,
3. The third certified question asks which approach Massachusetts would follow in determining the point at which actual injury or damage to property takes place under the policy provisions in this case. 9 The certifying judge identified six *687 so-called “trigger theories” that have been adopted by various courts, and the parties collectively have urged this court to consider three of those theories. 10
We agree with the certifying judge that “[a] crucial factor in determining when an injury occurs for purposes of insurance coverage is the nature of the injury.”
Acushnet River,
Notes
At the time the judge certified the questions to us, a similar dispute between Aerovox, Inc., and Fireman’s Fund Insurance Company was also before him. That dispute, however, was settled before oral argument in this court.
For other cases in which a Federal judge has declined to follow a State intermediate appellate court’s conclusion that the language is ambiguous and has instead expressed the view that the State’s highest court would not follow the intermediate appellate court, see
FL Aerospace
v.
Aetna Casualty & Sur. Co.,
“Paradoxically, the courts have almost uniformly ignored the insurers’ intent and distorted the phrase ‘sudden and accidental’ beyond recognition. With few exceptions, the courts have extended the coverage of policies containing the pollution exclusion ‘to mean just what they choose it to mean.’ ” The Pollution Exclusion Clause Through the Looking Glass, 74 Geo. L.J. 1237, 1240 (1986). The note correctly recognized three more recent opinions that denied coverage in particular circumstances as a possible “beginning of a trend of accurate judicial construction of the pollution exclusion.” Id. at 1264-1268.
See, e.g.,
United States Fidelity & Guar. Co.
v.
Star Fire Coals, Inc.,
For examples of opinions that conclude that the pollution exclusion clause should be construed in favor of the insured to mean “unexpected and unintended,” see
Claussen
v.
Aetna Casualty & Sur. Co.,
We decline to speculate on the proper construction of the exception, if a release or discharge, initially both accidental and sudden, continues for an extended period. As the discharge or release continues, at some point, presumably, it would likely cease to be accidental or sudden (even in the sense of unexpected).
Justice Kaplan wrote: “When, as in the present case, the allegations of the third-party complaint find apparent lodgment in the effective coverage of the policy, the insurer is obligated to defend. But it can, by certain steps, get clear of the duty from and after the time when it demonstrates with conclusive effect on the third party that as matter of fact — as distinguished from the appearances of the complaint and policy — the third party cannot establish a claim within the insurance. . . . What is not permitted is that an insurer shall escape its duty to defend the insured against a liability arising on the face of the complaint and policy, by dint of its own assertion that there is no coverage in fact: the insurer then stands in breach of its duty even if the third party fails in the end to support any such claim of liability by adequate proof.” Id.
“2. De Minimis Liability to Indemnify Pursuant to the Sterilite Decision
“The decision of the Massachusetts Appeals Court in
Sterilite Corp.
v.
Continental Casualty Co.,
The full statement of the judge’s question appears below:
“3. The 'Trigger’ Issue
“In the body of this opinion, this Court has held that the ‘occurrence’ provisions of the insurance policies here at issue require that the injury must take place during the policy period in order for coverage to be pro
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vided. In addressing when the injury took place in this case, the Court has identified six different approaches, each supported by case citation. These are: the wrongful act theory, the release theory, the injury-in-fact theory, the manifestation theory, the first discovery theory, and the continuous trigger theory. While the most analogous Supreme Judicial Court decision,
Continental Casualty Co.
v.
Gilbane Bldg. Co.,
Under the policies, “ ‘property damage’ means (1) physical injury to or destruction of tangible property which occurs during the policy period, including the loss of use thereof at any time resulting therefrom, or (2) loss of use of tangible property which has not been physically injured or destroyed provided such loss of use is caused by an occurrence during the policy period.”
Lumbermens urges us to adopt either the manifestation theory or the first-discovery theory. Belleville argues that the injury-in-fact theory is correct. This court already has rejected the wrongful act theory as contrary to the language of the policy. See
Continental Casualty Co.
v.
Gilbane Bldg. Co.,
