Full opinion text
OPINION AND ORDER SOFAER, District Judge: Plaintiff American Home Products Corporation (“AHP”), a diversified company manufacturing drugs, foods, and household products, is the defendant in fifty-four products-liability suits arising from AHP’s manufacture and sale of six pharmaceuticals: Ovral and L/Ovral (oral contraceptives), DES (Diethylstilbestrol), Mysoline, Atromid-S, Premarin, and Anacin. Defendant Liberty Mutual Insurance Company (“Liberty”), which provided AHP with insurance from 1944 until 1976, has refused to assume AHP’s burden of defense or to indemnify AHP in those lawsuits, because in each case physical harm did not become manifest until after termination of the insurance policies. In this action AHP seeks a judgment declaring that Liberty is obliged to defend and to indemnify AHP in the underlying lawsuits because, regardless of when physical harm became manifest, exposure to the alleged agents of harm occurred during the policy periods, thereby triggering coverage. Jurisdiction is based on diversity of citizenship, 28 U.S.C. § 1332 (1976), and New York law controls. AHP contends there are no disputed issues of material fact, and has moved for summary judgment awarding the declaration it seeks. Liberty opposes this motion, and has itself moved for partial summary judgment on the basis of a provision in the AHP policies which Liberty argues excludes coverage for all claims involving exposures to allegedly harmful substances after termination of Liberty’s coverage on November 1, 1976. Several courts have recently ruled on the scope of insurance policies covering liability for insidious diseases, which are illnesses that become manifest long after initial exposure to the substances believed to cause them. The policy provisions at issue in these cases were all variants of the Comprehensive General Liability Policy (“CGL”), a standard-form policy for liability coverage drafted during the 1960’s by representatives of the insurance industry to deal with the problem of liability for injuries caused over a period of time. Instead of covering only “accidents”, a word that connotes an event causing immediate or contemporaneous injury, the CGL was written to cover “occurrences”, defined to include “an accident, including injurious exposure to conditions, which results, during the policy period, in bodily injury ... neither expected nor intended from the standpoint of the insured.” CGL, Pl.Ex. 22 at 12. This change in terminology made clear the intent of insurers to provide coverage for insidious diseases. But the new language provided no definition of “bodily injury” other than the words themselves, thereby creating a basis for disputes as to the trigger of coverage. AHP’s insurance policies with Liberty were “manuscript” policies written specifically for AHP. Like the 1966 version of the CGL, however, AHP’s policies throughout the period relevant to this litigation provided liability coverage for “occurrences” that result in “personal injury, sickness or disease including death resulting therefrom ... sustained by any person.” An occurrence is defined by inference from Article IV: “This policy applies only to (1) personal injury, sickness or disease including death resulting therefrom ... which occurs during the policy period.” Pl.Ex. 20 at 3. The ultimate question under both the CGL language and the AHP policies at issue here is therefore the same: when does “injury, sickness or disease” occur? Under both policies, coverage exists only for injuries occurring during the policy period. Moreover, both the CGL and AHP’s policies require the insurer to defend any suit against the insured that seeks damages for an injury alleged to have occurred under the policy, even if the suit is groundless or fraudulent. See CGL, Pl.Ex. 22 at 1; AHP Policy, Pl.Ex. 20 at 1. One provision in AHP’s policies after 1968 differs from anything in the CGL, however. The provision Liberty relies on in its motion for partial summary judgment states: The policy does not apply to such injury, death or destruction caused by such continuous or repeated exposure any part of which occurs after the termination of the policy. Liberty contends that this provision renders these policies inapplicable to twenty-eight specified cases. See Urmston Aff t, Ex. 1. For the reasons that follow the policies in this case are construed as they are written — to require a showing of actual injury, sickness or disease occurring during the policy period, based upon the facts proved in each particular case. Thus, an occurrence of “personal injury, sickness, or disease” is read to mean any point in time at which a finder of fact determines that the effects of exposure to a drug actually resulted in a diagnosable and compensable injury. Depending upon the facts of each case, the drug involved, the period and intensity of exposure, and the person affected, an injury may occur in this sense upon exposure, at some point in time after exposure but before manifestation of the injury, and at manifestation. This construction is supported by the policy’s language and background, the intentions and expectations of the parties, and considerations of practicability and fairness. It provides liberal protection to the insured, without doing violence to the principle — long a part of the law of New York — that insurance policies are contracts under which insureds obtain all the protection for which they may reasonably be said to have paid, but not more. I. Meaning of The Policy Language Whether the contract between AHP and Liberty is ambiguous is of central importance to this case, and particularly to the disposition of this motion. AHP argues that the policies supply an ambiguous definition of “occurrence” that is susceptible to at least two plausible constructions. Under one construction coverage would be triggered by every exposure to a harmful substance that could ultimately result in bodily injury. Another construction would trigger coverage only when injury became manifest, which has been defined to mean when the injury was diagnosed or when it produced symptoms that placed or should have placed the injured person on notice. Relying on these alleged ambiguities, AHP invokes the well established rule that resolves ambiguities in insurance contracts in favor of the insured and against the insurer. See, e.g., Breed v. Insurance Co. of North America, 46 N.Y.2d 351, 353, 385 N.E.2d 1280, 1282, 413 N.Y.S.2d 352, 354 (1978). AHP argues that, in this case, the governing rule of construction requires application of the exposure theory, which favors manufacturers, or perhaps an even broader construction providing coverage at any point from exposure to manifestation. An exposure theory makes sense, AHP contends, because it recognizes that manufacturers intend to protect themselves against the long-term risk of claims associated with insidious diseases; “personal injury, sickness or disease” should therefore be read to cover every potentially injurious exposure during the policy period that results at any future time in a claim for injury. If an exposure theory were applied, Liberty would be responsible to pay any liability AHP incurs in any suit against AHP where the plaintiff ingested the harmful product during the policy period, irrespective of how long after termination a diagnosable injury, sickness, or disease developed, or manifested itself. Several courts have construed the CGL terms to provide coverage upon exposure. The Sixth Circuit, in Insurance Co. of North America v. Forty-Eight Insulations, Inc., 633 F.2d 1212, 1222 (6th Cir.1980), reh’g granted in part and denied in part, 657 F.2d 814 (1981), cert. denied, 454 U.S. 1109, 102 S.Ct. 686, 70 L.Ed.2d 650 (1981), found the terms “bodily injury” and “occurrence” inherently ambiguous as applied in the “progressive disease context.” The Court, faced with determining an asbestos manufacturer’s coverage under a CGL-derived policy, relied on that ambiguity, on medical testimony of the progressive nature of diseases caused by prolonged exposure to asbestos, and on the presumed intent of the parties, to read the contract as providing coverage for all potentially injurious exposures. See also Porter v. American Optical Corp., 641 F.2d 1128 (5th Cir.), cert. denied, 454 U.S. 1109, 102 S.Ct. 686, 70 L.Ed.2d 650 (1981). In Keene v. Insurance 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), the District of Columbia Circuit also found that exposure to asbestos triggered coverage under the “ambiguous” CGL terms. It concluded that an exposure theory most closely approximated the reasonable expectation of manufacturers, who purchase insurance in order to gain certainty and be free from all risk of liability arising out of products-liability suits. To protect this alleged expectation, the Court held that insurance coverage was triggered not only by every exposure, but by “exposure in residence,” when asbestos fibers were present in the body and causing further injury, and by every manifestation of an injury, sickness, or disease. 667 F.2d at 1048. Liberty counters with the claim that the relevant policy provisions unambiguously define manifestation as the trigger of insurance coverage. The average person, Liberty argues, would understand the terms “injury” and “disease” to mean an “abnormal condition” that “occurs” when it becomes manifest and is or should be discovered by the claimant. Thus Liberty argues that, under the policy, it incurs no duty to defend unless the claimant seeks recovery for an injury, sickness, or disease that allegedly became manifest while the policy was in effect, and that it has no duty to pay AHP sums for which AHP becomes liable unless the alleged injury became manifest during coverage. Some courts have indeed rejected the exposure theory and found that, properly construed, the CGL provisions support a manifestation theory. See, e.g., Eagle-Picher Industries, Inc. v. Liberty Mutual Insurance Co., 523 F.Supp. 110 (D.Mass.1981), modified, 682 F.2d 12 (1st Cir.1982); American Motorists Insurance Co. v. E.R. Squibb & Sons, Inc., 95 Misc.2d 222, 406 N.Y.S.2d 658 (N.Y.Sup.Ct.1978). They reason that manufacturers and insurance companies intend to cover only risks that ripen into claims, and that “bodily injury” in the CGL cannot logically be read to mean injurious exposures that are not themselves injuries. Thus, District Judge Zobel, addressing policy coverage for asbestos related diseases, cogently reasoned: All policies except the later group of those written by Liberty Mutual define occurrence as “an accident or a continuous or repeated exposure to conditions which results, during the policy period, in personal injury....” This definition is broad and inclusive. Each “occurrence” is made up of two components, initial exposure or accident and resulting injury; neither one without the other would be sufficient. There can be no question but that the aspect of the occurrence which must take place within the policy period, however, is the “result”, that is, the time when the accident or injurious exposure produces personal injury. The time-limiting phrase “during the policy period” always follows the word “results” and frequently is set off by commas, so that it can modify only the preceding verb “results”. Thus, the definitional language explicitly focuses on the result rather than the cause as the component to which coverage is linked. Eagle-Picher Industries, 523 F.Supp. at 114. On appeal, the First Circuit agreed that “[t]he policies clearly distinguish between the event which causes injury — the accident or exposure — and the resulting injury or disease. Yet ... it is the resulting injury, not the exposure, which must take place ‘during the policy period’ in order to trigger coverage ....” Eagle-Picher Industries, 682 F.2d at 17 (emphasis in original). Liberty relies on these cases in seeking denial of AHP’s motion for summary judgment; it argues for partial summary judgment, moreover, based on the special limiting clause in its policies after 1968, which it claims incontrovertibly excludes coverage for several of the claims referred to in this action. Insofar as AHP and Liberty, attack each other’s construction, both sides are correct: neither the exposure nor the manifestation theory can be wholly justified by the policy language. A. Governing Legal Principles AHP correctly argues that insurance contracts must be liberally construed, with ambiguities in the policy language resolved in favor of the insured. See Pan American World Airways, Inc. v. Aetna Casualty & Surety Co., 505 F.2d 989, 999 (2d Cir.1974); Breed v. Insurance Co. of North America, 46 N.Y.2d 351, 353, 385 N.E.2d 1280, 1282, 413 N.Y.S.2d 352, 354 (1978). This rule of construction, in fact, appears to be the single factor that unifies the discordant opinions applying the CGL and its derivatives to insidious diseases. Whether or not explicitly finding ambiguities, and irrespective of the construction adopted, every court construing these provisions has reached the result that extended coverage to the insured. See, e.g., Eagle-Picher Industries, 682 F.2d at 17 (manifestation); Keene, 667 F.2d at 1041 (manifestation and exposure); Forty-Eight Insulations, 633 F.2d at 1223 (exposure). Under New York law, however, a court should apply its own construction to a policy’s terms only after it has exhausted every effort to derive the meaning of the terms that accurately reflects the intent of the parties. An insurance policy is a contract which, like any other contract, must be construed to effectuate the parties’ intent as expressed by their words and purposes. McGrail v. Equitable Life Assurance Society, 292 N.Y. 419, 424, 55 N.E.2d 483, 486 (1944); MetPath Inc. v. Birmingham Fire Insurance Co., 86 A.D.2d 407, 449 N.Y.S.2d 986 (1st Dep’t 1982). If the words of the contract are unambiguous, establishing only one meaning when read in the context of the entire policy, then a New York court must enforce the plain meaning of the words and refrain from making or varying “the contract of insurance to accomplish its notions of abstract justice or moral obligation.” Breed, 46 N.Y.2d at 355, 385 N.E.2d at 1283, 413 N.Y.S.2d at 355; see Coppotelli v. Insurance Co. of North America, 484 F.Supp. 1327, 1329 (E.D.N.Y.1980). The principle that requires courts to resolve ambiguities in insurance contracts in favor of the insured, and against the insurer, is not a fundamental departure from established contract principles. Rather, it is one instance, albeit special and emphatic, of the widely recognized rule that resolves ambiguity in a contract against the contract’s drafter. Greaves v. Public Service Mutual, Inc., 5 N.Y.2d 120, 155 N.E.2d 390, 181 N.Y.S.2d 489 (1959). Insurance contracts are usually contracts of adhesion in that their terms are generally dictated rather than negotiated. Courts therefore require insurance companies to be clear and unambiguous in creating limitations on coverage. “[T]he insurer has the burden of establishing that ‘the words and expressions used not only are susceptible of [the] construction [that the insurer advocates], but that it is the only construction that can fairly be placed thereon.’ ” Bronx Savings Bank v. Weigant, 1 N.Y.2d 545, 552, 136 N.E.2d 848, 851, 154 N.Y.S.2d 878, 883 (1956) (quoting Hartol Products Corp. v. Prudential Insurance Co., 290 N.Y. 44, 49, 47 N.E.2d 687, 690 (1943)). Accord, Vargas v. Insurance Co. of North America, 651 F.2d 838, 839 (2d Cir.1981). Nevertheless, intent remains controlling. No construction of an ambiguous provision is permitted that is inconsistent with the contract’s plain meaning or with the parties’ clear intentions. As the Second Circuit stated in Union Insurance Society of Canton, Ltd. v. William Gluckin & Co., 353 F.2d 946 (2d Cir.1965): The terms of an insurance policy are usually what the insurance company chooses to make them. That is the rationale of the general rule that any ambiguity is to be resolved liberally in favor of the insured. However, this rule of construction “is applicable only where the ambiguity persists after all other aids to construction are used. It certainly does not foreclose the use of parol evidence initially to resolve such ambiguity.” Aetna Ins. Co. v. Dickler, 100 F.Supp. 875, 878 (S.D.N.Y.1951). It is also true that there would be much less reason for applying such a rule if the clause in issue was drafted by, and put in the policy at the behest of, the named insured. 353 F.2d at 951 (citation omitted). To disregard express language in an insurance contract because of a claimed ambiguity “would violate the more fundamental rule of construction” that requires a court to construe the contract as a whole and, whenever possible, give effect to all of its parts. Spencer, White & Prentis, Inc. v. Pfizer, Inc., 498 F.2d 358, 363 n. 23 (2d Cir.1974). New York law therefore requires a construction of the CGL language based on the plain meaning of the words employed, read in the context of the policy as a whole, the purposes sought to be accomplished, and the relevant surrounding circumstances. See Murray Oil Production v. Royal Exchange Assurance Co., 21 N.Y.2d 440, 445, 235 N.E.2d 765, 288 N.Y.S.2d 618 (1968); Vanguard Insurance Co. v. Polchlopek, 18 N.Y.2d 376, 222 N.E.2d 383, 275 N.Y.S.2d 515 (1967). B. Proposed Constructions of the Parties Neither construction proffered by the parties is supported by the plain meaning of the terms employed. 1. The Exposure Theory. An exposure theory is inconsistent with the policies’ plain meaning, and AHP has offered no evidence or explanation to demonstrate how an “occurrence” could logically include every exposure to the substances it manufactures. The policies require that the resulting injury and not the exposure occur “during the policy period.” Moreover, the policies were designed to protect against liability from law suits brought because of compensable injuries. To that end they cover “occurrences” wherein both exposure and an injury take place. The only New York case on point also rejected the exposure theory as unsupported by the language of a policy that covered “[a]n accident or injurious exposure to conditions which results, during the policy period, in bodily injury....” The injured plaintiffs, who had sued the insured, were the daughters of women who had ingested DES while pregnant with the plaintiffs in 1952, 1953, and 1961 respectively; the plaintiffs thereafter developed cervical cancers that were discovered in 1970, 1971, and 1975. Justice Greenfield concentrated on the policy language: A reading of the policy language would appear to indicate that coverage is predicated not on the act which might give rise to ultimate liability, but upon the result. It would be a strained interpretation to construe the occurrence clause as though it covered “exposure during the policy period which results in bodily injury.” It is the result which is keyed to the policy period, and not the accident or exposure. American Motorists Ins. v. E.R. Squibb & Sons, 95 Misc.2d 222, 406 N.Y.S.2d 658, 659-60 (N.Y.Sup.Ct.1978) (emphasis in original). A limited version of the exposure theory, adopted in some litigations, is at least linguistically respectable. Some courts, relying on medical evidence, have found that, on exposure, asbestos particles enter the body and cause discrete injuries to lung and other tissue, and that these injuries are sufficient to establish coverage under the CGL language, even though they must aggregate over time to cause diseases and sicknesses such as asbestosis, carcinoma, and mesothelioma. Keene, 667 F.2d at 1044; Insurance Co. of North America v. Forty-Eight Insulations, Inc., 451 F.Supp. 1230, 1239 (E.D.Mich.1978), modified, 633 F.2d 1212, 1222-23 (6th Cir.1980), cert. denied, 454 U.S. 1109, 102 S.Ct. 686, 70 L.Ed.2d 650 (1981). But see, e.g., Eagle-Picher, 523 F.Supp. at 115 & 682 F.2d at 17 (medical evidence establishes that (1) not every exposure to asbestos results in injury of any sort, since body’s natural mechanisms often remove fibers before they become embedded; and (2) even when discrete injuries are caused, they frequently fail to lead to any compensable injury). AHP cannot rely on the rationale of cases that have found immediate injury from the ingestion of asbestos fibers, because the drugs at issue in this ease differ markedly from asbestos in the manner in which they are alleged to injure humans. AHP has failed to submit any proof with respect to the effects of any of the drugs involved, and has not claimed that any of them injures upon every exposure. The record establishes without material dispute, moreover, that at least two of the drugs at issue (Ovral and DES) do not injure upon every exposure. Flessa Aff’t, Def.Ex. 35 (Feb. 14, 1982) (Ovral); Mattingly Aff’t, Def.Ex. 36 (Feb. 10, 1982) (DES). As discussed below, a particular plaintiff might be able to establish, despite this evidence, that a particular exposure to one of the drugs at issue constituted an actual and compensable injury. No evidence has been presented, however, that could support a general declaration that every exposure to any of the drugs at issue in this case causes injury, and therefore triggers coverage, under the AHP policies. Advocates of the exposure theory have suggested that it has some inferential support in the New York Court of Appeals’ holdings that an injury occurs upon exposure for purposes of the statute of limitations. See, e.g., Steinhardt v. Johns-Manville Corp., 54 N.Y.2d 1008, 430 N.E.2d 1297, 446 N.Y.S.2d 244 (1981). This rule can be traced back to decisions that appear to have assumed that exposure to harmful chemicals does in fact injure bodily tissue. See, e.g., Thornton v. Roosevelt Hospital, 47 N.Y.2d 780, 781, 391 N.E.2d 1002, 1004, 417 N.Y.S.2d 920, 922 (1979). But these statute-of-limitation decisions do not in fact turn on the untenable proposition that actual injury always occurs upon the ingestion of asbestos fibers, or other bodily invasion. They rest, rather, on the costs and uncertainty that the Court of Appeals long ago concluded would be created by a general rule that only “discovery” triggers a statute of limitation, and on the state legislature’s failure to amend the applicable New York statute to extend the time in which plaintiffs may bring suits for the consequences of insidious diseases, other than those caused by “Agent Orange.” See Schwartz v. Heyden Newport Chemical Corp., 12 N.Y.2d 212, 218-19, 188 N.E.2d 142, 144-45, 237 N.Y.S.2d 714, 718-19 (1963); N.Y.C.P.L.R. § 214-a (McKinney Supp.1982). These policy considerations have no bearing on the construction of insurance contracts; indeed, every court that has examined CGL policies has refused to give weight to definitions of injury articulated in statute-of-limitation cases. See, e.g., Keene, 667 F.2d at 1043 & n. 17; see generally Wrubel, Comment, Liability Insurance for Insidious Disease: Who Picks Up the Tab?, 48 Fordham L.Rev. 657, 669-70 (1980). Finally, the exposure theory is made particularly untenable in this case by the special limitation added to the AHP-Liberty policies since at least 1968, which excludes coverage for injuries “caused by continuous or repeated exposure, any part of which occurred after termination of the policy.” If every exposure were an occurrence under the policies, the limitation would have no meaning; it can have meaning only if the occurrences insured against are the injuries, diseases, or sicknesses caused by exposures, and not the exposures themselves. 2. The Manifestation Theory. Liberty contends that the policy words “injury”, and “disease” or “sickness” are ordinary words which the average person would understand respectively to mean “damage” and an “abnormal condition,” and that the average person would think of these consequences as having occurred when they take place or are discovered. The First Circuit accepted this view in extending coverage to the claims at issue in Eagle-Picher: [W]e agree with the district court that the common, ordinary meaning of the policy language supports the manifestation theory. An individual with tiny sub-clinical insults to her lungs would not say that she had any injury or disease, given one expert’s testimony that “over 90% of all urban city dwellers have asbestos-related scarring.” Rather, she would say that a disease resulted when she had symptoms which impaired her sense of well-being, or when a doctor was able to detect sufficient scarring to make a prognosis that the onset of manifested disease was inevitable. “Injury” is defined by Webster as “hurt, damage, or loss sustained”; it is a broad term which covers the “result of inflicting on a person or thing something that causes loss, pain, distress, or impairment.” As sweeping as this definition is, it is difficult to consider sub-clinical insults to the lung to constitute an “injury” when these insults do not cause “loss, pain, distress, or impairment” until, if ever, they accumulate to become clinically evident or manifest. 682 F.2d at 19 (footnote omitted). The “manifestation” theory adopted in Eagle-Picher, and now advanced by Liberty, is in part a departure from what has conventionally been understood as the manifestation approach. The meaning of manifestation proposed in prior cases is that an injury, sickness, or disease becomes manifest only when symptoms become noticeable or a diagnosis is made. “The manifestation theorists contend that the date of manifestation is ‘the date on which the condition became known or should have become known to plaintiff or the date on which plaintiff’s condition was medically diagnosed, whichever comes first.’ ” Wrubel, supra, 48 Fordham L.Rev. at 668 n. 58 (quoting Forty-Eight Insulations, 451 F.Supp. at 1238). Thus stated, the manifestation theory refuses to recognize that any bodily injury may have existed prior to the appearance of symptoms or an actual diagnosis. Under this construction, the manifestation theory would be convenient to apply, but it is inconsistent with the policy language. The ordinary person may construe an “occurrence” of injury to mean manifestation in the sense of discovery. Discovery of an injury or disease is a truly significant event which makes the victim aware of what had theretofore been only a latent, medical problem without conscious significance. The plain meaning of the policy language is not measured, however, by the understanding of a lay person, but by the understanding of a person engaged in the insured’s course of business. See Champion International Corp. v. Continental Casualty Co., 546 F.2d 502, 505-06 (2d Cir.1976); McGrail v. Equitable Life Assurance Society, 292 N.Y. 419, 424-25, 55 N.E.2d 483, 486 (1944); Loblaw, Inc. v. Employers’ Liability Assurance Corp., 85 A.D.2d 880, 446 N.Y.S.2d 743, 745 (4th Dep’t 1981). From the point of view of a drug manufacturer, familiar with the potential development of insidious diseases from its products, and seeking to insure against liability for harm, an injury, sickness, or disease would include any compensable, medical condition that is fully developed, even though dormant. For example, a particular drug may cause a heart attack in some women long after they ingest it. Under the manifestation theory, liability for the heart attack would be covered by a CGL-type policy in effect when the injury occurs. But the manufacturer would also expect that a latent, undiscovered disease caused by the same drug prior to the heart attack would be covered by a policy in effect at the time it arose, regardless of when the disease was discovered or the heart attack or some other manifestation occurred. The CGL policy language covers all injuries, sicknesses, or diseases that occur during coverage, not merely those that become manifest. The restriction imposed on the policy language by the manifestation approach is, moreover, inconsistent with insurance law principles. If the policy language were deemed ambiguous enough to permit reading in a manifestation requirement, the process of doing so would be unacceptable in New York because that reading is not “the only construction which may fairly be placed on” the policy’s words, Filor, Bullard & Smyth v. Insurance Co. of North America, 605 F.2d 598, 602 (2d Cir.1978), cert. denied, 440 U.S. 962, 99 S.Ct. 1506, 59 L.Ed.2d 776 (1979) (emphasis omitted) (citing Lachs v. Fidelity & Casualty Co., 306 N.Y. 357, 365-66, 118 N.E.2d 555, 559 (1954)), and because the construction proposed would be more restrictive than one that treated as “occurrences” all injuries, diseases, and sicknesses, whether manifest or merely discoverable, see Thomas J. Lipton, Inc. v. Liberty Mutual Insurance Co., 34 N.Y.2d 356, 361, 314 N.E.2d 37, 357 N.Y.S.2d 705, 708 (1974); National Screen Service Corp. v. United States Fidelity & Guaranty Co., 364 F.2d 275, 277 (2d Cir.1966); Vargas v. Insurance Co. of North America, 651 F.2d 838, 839-40 (2d Cir.1981). Significantly, courts that have accepted the manifestation theory have invariably done so in extending, rather than restricting, the coverage of an ambiguous policy. The limitation provision found in AHP’s policies after 1968, and relied upon by Liberty to refute the exposure theory, also refutes the manifestation approach. The limitation excludes from coverage injuries “caused by continuous or repeated exposure, any part of which occurred after termination of the policy.” If the standard-form, CGL language, standing alone, triggered coverage solely by manifestation or discovery, then this special provision would have no reasonable meaning, since all occurrences to which it could apply would have already become manifest during the policy period. No insured would conceivably agree to give up coverage for liability in cases where every necessary prerequisite for liability has occurred during the policy period, merely because the plaintiff continued thereafter to be exposed to the cause of his already manifest injury. To the contrary, the limitation provision suggests that, absent its application, the policy could arguably apply to injury, sickness or disease, caused in part by exposure during the policy period and in part thereafter. In protecting itself against such claims, Liberty used language that significantly informs the construction of the “occurrence” clause, rendering its manifestation theory as untenable as the same language renders the exposure theory suggested by AHP. The manifestation theory is also advocated on the basis of decisions construing health and accident insurance policies, and worker compensation statutes. Courts apply the manifestation theory in construing health and accident policies in order to extend coverage to individuals who suffered from latent but unknown injuries or diseases prior to coverage, which only manifested themselves or were discovered during coverage. See, e.g., Silverstein v. Metropolitan Life Insurance Co., 254 N.Y. 81, 84, 171 N.E. 914, 914-15 (1930). This result is reached, moreover, because the parties to such insurance contracts are concerned with the disabling results of injuries and illnesses, and not their medical ascertainability. In a typical health insurance case, Cohen v. North American Life & Casualty Co., 150 Minn. 507, 508, 185 N.W. 939, 939 (1921), for example, the Supreme Court of Minnesota explained: “The insurer intended to give and the insured expected to get indemnity if illness or sickness [occurred] .... They were not concerned with the latent or remote cause of it. The cause of the disease insured against is not mentioned in the policies as a condition of liability.” By contrast, the CGL language and AHP’s policies are contracts in which the risk insured against is not illness itself, but liability resulting from the manufacture or sale of a product, and in which the parties are expressly concerned with diseases that are caused over time by injurious exposure, and hence often exist in a latent form before discovery: The definition of “occurrence” to include exposure over time to injurious conditions reflects the parties’ mutual awareness of the latency factor that will have to be assessed in determining coverage. It cannot be said that the manufacturer of a product that poses an insidious hazard to the health of others is truly unaware that the damages for which he may be found liable' arose out of bodily injury that remained latent for some time. Wrubel, supra, 48 Fordham L.Rev. at 671 (footnotes omitted). Resort to the manifestation theory in construing worker compensation laws provides no support for the theory’s application in construing the private contracts at issue in this case. In that context, and with characteristic flair, Learned Hand said that “a disease is no disease until it manifests itself.” Grain Handling Co. v. Sweeney, 102 F.2d 464, 466 (2d Cir.), cert. denied, 308 U.S. 570, 60 S.Ct. 83, 84 L.Ed. 478 (1939). The claimant’s disease (dormant tuberculosis) long antedated his last employment, but Judge Hand treated it as having occurred when it disabled the claimant. As Judge Hand noted, however, the Longshoremen’s Act which he was interpreting “is not concerned with pathology, but with industrial disability,” id., and the legislature’s purpose in passing such legislation was to make the costs of all disabling injuries and illnesses a part of the cost of production, id. at 465. Similarly, in Travelers Insurance Co. v. Cardillo, 225 F.2d 137 (2d Cir.), cert. denied, 350 U.S. 913, 76 S.Ct. 196, 100 L.Ed. 800 (1955), the Second Circuit held that under the same Act a disabled employee’s last employer would be entirely liable for the individual’s hearing disability, where it was impossible to determine how much hearing loss resulted from any prior employment. 225 F.2d at 144. Accord, General Dynamics Corp. v. Benefits Review Board, 565 F.2d 208 (2d Cir.1977). In this situation, coverage was legislatively mandated; the Court’s problem was to determine which employer’s fund should be tapped to pay the benefits required. By contrast, coverage under the CGL language depends upon tort liability, not legislative mandate, and is supposed to extend only to those cases upon which the contracting parties agreed, not to a point that is convenient or socially desirable. The practical, legislatively supported rules adopted by the Second Circuit in worker compensation cases are, therefore, no proper basis for resolving the private, contractual disputes presented here; and the language and purpose of the contracts at issue here do not permit a manifestation theory that treats as insignificant the development from injurious exposure of a latent but real illness. C. Plain Meaning of the Policy Provisions. 1. The Occurrence Clause. The plain meaning of the “occurrence” clause is no •secret to the parties. Courts and writers have recognized that “occurrence” is most logically construed to include only those injuries, sicknesses, or diseases that are proved to have existed during coverage. For example, in Forty-Eight Insulations the Sixth Circuit stated: In each case where a plaintiff sues an asbestos manufacturer, a hearing could be held to determine at what point the build-up of asbestos in the plaintiff’s lungs resulted in the body’s defenses being overwhelmed. At that point, asbestosis could truly be said to “occur”. From then on, all companies which insured the manufacturer would be treated as being “on the risk”. 633 F.2d at 1217 (footnote omitted); see also Schering Corp. v. Home Insurance Co., 544 F.Supp. 613, 616 (E.D.N.Y.1982). See generally Wrubel, supra. Indeed, while Liberty has advanced its position as based on a manifestation theory requiring knowledge or actual diagnosis, Liberty at times defines “manifestation” to include the unknown presence of diagnosable and compensable disease. See, e.g., Portmann Dep., Pl.Ex. 3 at 136, 138; Stevens Dep., Pl.Ex. 8 at 113-17. This straight-forward interpretation has been rejected, however, as impractical and unfair. According to critics, to require the courts and the parties to CGL-type contracts to determine coverage in the many thousands of pending and anticipated latent-injury claims on a case-by-case basis would be impossible, e.g., Forty-Eight Insulations, 633 F.2d at 1218, and also inconsistent with the reasonable expectations of the insured, and with developing tort-law doctrine in the latent-disease area, e.g., Keene, 667 F.2d at 1044 n. 20; Forty-Eight Insulations, 633 F.2d at 1219. These practical and ethical concerns are shown below to be unpersuasive. Before addressing them, however, a full appraisal of the policy’s plain meaning is in order to demonstrate why, linguistically at least, the injury-in-fact approach is plainly the proper construction. The most basic demand of the policy language is that to establish Liberty’s liability the insured must prove that an “occurrence” — injury, sickness, or disease— arose during the policy period. The plain language demands that the insured prove the cause of the occurrence (accident or exposure), the result (injury, sickness, or disease), and that the result occurred during the policy period. An exposure that does not result in injury during coverage would not satisfy the policy’s terms. On the other hand, a real but undiscovered injury, proved in retrospect to have existed at the relevant time, would establish coverage, irrespective of the time the injury became manifest. This approach is faithful to the policy language because it gives separate meaning to the three concepts of exposure, injury, and discovery. The policy expressly gives separate significance to the first two concepts, and its provisions strongly suggest that an occurrence means something different — and more expansive — than manifestation or discovery. On the other hand, nothing in the policy language precludes a finding that a single exposure, or a single period of exposures, immediately injured a person to a compensable extent; similarly the policy language also permits courts or juries to find that injury, sickness, or disease, occurred in a particular case at the time it became manifest. So long as the insured is held liable for an identifiable and compensable injury, sickness, or disease that is shown to have existed during coverage, that liability will be insured against whether or not the injury coincides with exposure or manifestation. To state this result in the abstract is, of course, much easier than to apply it in particular contexts, given the variables involved. Injuries that are diagnosable and compensable may be established in particular cases at almost any point in the period between exposure and manifestation, depending among other things upon the nature of the substance involved, the intensity (amount or duration) of the exposure, the capacity of the individual exposed to withstand the danger, and chance. For example, although exposure to asbestos does not usually injure seriously enough to constitute an “occurrence” in the context of a liability insurance policy, a finder of fact might, nevertheless, find that a particular exposure or period of exposure contemporaneously caused a compensable injury, sickness, or disease during coverage. If an expert testified that, in his opinion, formed to a degree of reasonable medical certainty, a compensable injury resulted from the particular, alleged exposure, a finding could properly be reached that compensable injury was caused by that exposure, even if it later leads to other, compensable injuries that occur after coverage has ended. Similarly, the manifestation of a long-latent injury or illness may itself constitute an injury, sickness, or disease. For example, the manifestation of asbestosis or mesothelioma, although previously developed but undiscovered, may also constitute an occurrence if accompanied by some additional injury, such as the coughing of blood, or some other identifiable and compensable complication. In sum, the insured would be permitted under a plain reading of the policy to establish that occurrences have taken place at any or all points from exposure to manifestation, on the ground that identifiable injuries have been proved to have occurred at each point to a reasonable degree of medical certainty. The language remains clear even though its application is complicated by the many, strong variables at work in the insidious disease process. The general rule applied in health and property damage insurance cases provides a strong analogy. In those areas, courts construe language such as “injury”, “damage”, and “accident” to occur at any point in time that a compensable event could have been or was ascertained. The indicated presence of silicosis was held to be “bodily injury” in Tomnitz v. Employers’ Liability Assurance Corp., 343 Mo. 321, 121 S.W.2d 745 (1938), and therefore compensable under a liability policy in effect at that time, even though the disease manifested itself through symptoms only after the policy had expired. Similarly, casualty insurance coverage is extended to a home “damaged” by slow-moving causes, such as a shifting foundation or an attack of termites, as soon as the effect of those causes is shown to have inflicted measurable, compensable, albeit unascertained, damage on the policyholder during the policy period. See, e.g., Harman v. American Casualty Co., 155 F.Supp. 612 (S.D.Cal.1957); Snapp v. State Farm Fire & Casualty Co., 206 Cal.App.2d 827, 24 Cal.Rptr. 44 (1962). Here, again, as in the private contracts in this case, compensable injury may be shown to occur in particular cases at any time from initial exposure until manifestation. 2. The Limitation Provision. The special limitation, appearing first in the AHP-Liberty policy for 1964 and made effective in 1968, provides strong support for this reading of the plain language. Liberty argues correctly that the provision is unambiguous, but its meaning is not the one Liberty suggests. Rather, on its face the provision removes from coverage only injury, death, or destruction that is caused by continuous or repeated exposure occurring in part after November 1, 1976, the date AHP terminated the policy. It does not remove from coverage harm caused wholly by exposure occurring prior to November 1, 1976. Nothing in the language of the provision takes such harm out of the policy simply because exposure to the same products continued after November 1, 1976, or indeed because further harm may have occurred from such continued exposure. If, in a particular case, pre-November 1, 1976 exposure is found to have caused a particular harm, no exposure after November 1, 1976 would be a cause of that particular harm; such harm is not “caused by ... exposure any part of which” occurred after November 1,1976, because all of that harm-causing exposure occurred before that date. Plaintiff and defendant agree that there is no evidence about who wrote the limitation provision, when it was written, or when it first appeared in AHP policies. The 1952 policy does not contain the provision, the policies from 1964 to 1976 do contain it, and the parties have been unable to locate the policies from 1953 to 1963. Moreover, no reliable evidence exists about the original purpose of the provision or about the parties’ understanding of its meaning, prior to November 1, 1976. ■ Nor has any possibly relevant evidence been submitted about whether the addition of the contested provision was reflected in premium amounts. Cf. Pan American World Airways, Inc. v. Aetna Casualty & Surety Co., 505 F.2d 989, 1003 (2d Cir.1974) (recognizing that amount of premium varies with scope of an insurance policy’s coverage). Some evidence does exist, however, in the depositions, and as discussed below it supports the interpretation of the limiting provision suggested here, as well as the proposition that the parties intended and understood basic policy coverage to apply to injuries shown in fact to have occurred during the policy period. 3. Obligation to Defend. The plain language of the policies at issue makes clear that Liberty is obliged to defend any suit, however meritless, seeking to impose a liability upon AHP that is covered by the policy. The policies provide: With respect to such insurance as is afforded by this policy for personal injury liability ... the company [insurer] shall: (a) defend any suit against the insured alleging such injury, sickness, disease or destruction and seeking damages on account thereof, even if such suit is groundless, false or fraudulent.... E.g., Pl.Ex. 20, Sec. II. This expansive language must, under New York law, be construed broadly to provide coverage. See, e.g., Chertok v. Hotel Salisbury, Inc., 516 F.Supp. 766, 767 (S.D.N.Y.1981); Goldberg v. Lumber Mutual Casualty Insurance Co., 297 N.Y. 148, 77 N.E.2d 131 (1948); 31 N.Y.Juris. § 1324 (1963). Liberty concedes the principle that the duty to defend is broader than the duty to indemnify, in that it must defend meritless suits, so long as they could conceivably result in a liability covered by the policy. But Liberty relies upon the equally valid principle that it has no duty to defend claims which may have merit, but for which liability coverage does not exist because injury occurred outside the policy period. See Appleman, Insurance Law Practice § 4684 at 72 (1979). New York’s Court of Appeals has established that “if we can determine that no basis for recovery within the coverage of the policy is stated in the complaint, we may sustain defendant’s refusal to defend.” Lionel Freedman, Inc. v. Glens Falls Insurance Co., 27 N.Y.2d 364, 368, 267 N.E.2d 93, 95, 318 N.Y.S.2d 303, 305 (1971). Furthermore, even if a complaint states a basis for possible recovery, once an insurer is able to “confine the claim” — exclude the possibility of a recovery for which it has provided insurance — the insurer has no further duty to defend. See Lee v. Aetna Casualty & Surety Co., 178 F.2d 750, 752-53 (2d Cir.1949) (L. Hand, J.). If manifestation in the form of discovery were required to trigger coverage under AHP’s policy, then its motion for summary judgment with respect to the obligation to defend would have to be denied. But the injury-in-fact standard adopted here permits a declaration in AHP’s favor requiring Liberty to defend until it has “confined the claim” in any underlying case by demonstrating that coverage will be denied even if the case succeeds. As Liberty itself argued in another suit in this District, an insured is entitled to a defense if the underlying complaint “permits proof” of facts establishing coverage, or, as in this case, if the complaint does not exclude the possibility that injury, sickness, or disease in fact occurred during the policy period. See Pl.Ex. 42 at 16-17; Emons Industries, Inc. v. Liberty Mutual Fire Insurance Co., 481 F.Supp. 1022 (S.D.N.Y.1979). This showing must be made in each underlying litigation, and is an inappropriate issue to resolve in a declaratory judgment action, where the underlying cases are not before the Court. So long as the allegations in a case could conceivably result in liability covered by a policy at issue, Liberty must defend. Tenneco Chemical, Inc. v. Employers Mutual Liability Insurance Co., 1968 Fire & Casualty Cas. (CCH) 984, 985 (S.D.N.Y.1968) (Tyler, J.). This standard also applies to those suits that Liberty claims are controlled by the special limitation provision. So long as a complaint permits proof that an occurrence took place within the coverage period, Liberty must defend the suit until and unless it is able to establish, not only that post-1976 exposures took place, but also that no compensable injury was diagnosable before those exposures commenced. II. Background of the CGL and Intention of the Parties Both AHP and Liberty claim that the background of the CGL — its history and purpose — lends support to their respective theories. AHP argues that the CGL’s drafters indisputably rejected the manifestation theory, and thereby signalled an intent consistent with an exposure approach. Liberty replies that the “legislative history” of the CGL is irrelevant here, and that it in any event involves issues of fact that cannot be resolved without an evidentiary hearing. Furthermore, Liberty contends, the evidence relied upon by AHP does not support an exposure theory, and the relationship between the parties — especially AHP’s acceptance of the provision limiting coverage to injuries resulting only from exposure during coverage, and the swine-flu policy adopted by the parties in 1976 — refutes the notion that the parties ever intended to adopt an exposure theory. The background of the CGL, and the relationship that existed between these parties, are relevant in supplementing the policy’s plain meaning. Union Insurance Co. of Canton, Ltd. v. William Gluckin & Co., 353 F.2d 946, 951 (2d Cir.1965). Where the policy language is unambiguous, a court in New York may not look to circumstances external to the contract to alter its meaning. See, e.g., Breed, 46 N.Y.2d at 355, 385 N.E.2d at 1283, 413 N.Y.S.2d at 355; Teal v. Place, 85 A.D.2d 788, 445 N.Y.S.2d 309, 312 (3d Dep’t 1981). Parol evidence can provide strong corroborative proof, however, of the parties’ intent as suggested in their words. See Theatre Guild Productions, Inc. v. Insurance Corp. of Ireland, 25 A.D.2d 109, 267 N.Y.S.2d 297, 299 (1st Dep’t 1966), aff’d, 19 N.Y.2d 656, 225 N.E.2d 216, 278 N.Y.S.2d 625 (1967). The evidence here shows, as the parties respectively contend, that neither the exposure nor the manifestation theory was intended. Rather, the evidence establishes that the CGL draftsmen, as well as the parties, contemplated coverage only for injuries shown in fact to have occurred during periods of coverage. A. History and Purpose of the CGL. The CGL evolved out of the difficulties faced by courts and parties in dealing with personal injuries and property damage sustained as a result of gradual processes. Pri- or to 1966, general liability policies covered liability “because of bodily injury, sickness or disease, including death at any time resulting therefrom, sustained by any person, caused by accident and arising out of the hazards hereinafter defined.” 1 R. Long, Law of Liability Insurance § 11.01 at 11-4 (1979) (emphasis added). The word “accident” suggested an intent to cover only sudden, unexpected, but identifiable events. The courts were left in doubt as to whether, and to what extent, the standard policy was meant to cover liability for injuries that resulted from gradual processes, rather than from sudden events. The insurance industry responded to the uncertainty created by the “accident” orientation of pre-1966 liability policies by establishing a task force to draft what eventually became the CGL. In 1960, the Mutual Insurance Rating Bureau (“Mutual”) and the National Bureau of Casualty Underwriters (“National”) established several committees, which engaged in the revision process. Liberty, a member of Mutual, became actively involved; Richard Schmalz, then an attorney for Liberty, was a member of the Joint Drafting Committee, and Gilbert Bean, a Liberty officer, became a member of the Joint Rating Committee, which ultimately approved the form policy. Schmalz Dep., Pl.Ex. 23 at 16. The task force substituted the “occurrence” approach now in the CGL and in AHP’s policies for the “accident” approach, and it expressly provided that an occurrence included any injury or damage that resulted, not only from an accident, but also from injurious exposure over an extended period. This change adopted the result reached by courts that construed “accident” to include injuries resulting from long exposures. The new CGL failed, however, to resolve definitively the time injury should be found to occur in insidious disease cases. The CGL, like its predecessor, requires only that an injury take place during the coverage period. But, since the injuries expressly covered under the CGL include those resulting from long-term injurious exposure, the difficulty of determining time of injury was certain to be even greater under the CGL than it had been under predecessor policies. The insurance industry task force recognized this problem from the very outset of its labors, just as courts had recognized by then that an injury could occur in scientific fact long before it became manifest. See, e.g., Tomnitz v. Employers’ Liability Assurance Corp., 343 Mo. 321, 121 S.W.2d 745 (1938). Nevertheless, the task force refused to alter the standard policy language to define precisely the time of injury; in the process, moreover, they refused to accept language that would have incorporated into the CGL either the manifestation or the exposure theory. Schmalz Dep., Pl.Ex. 23 at 65-69. Substantial evidence supports the view that' the CGL draftsmen rejected the manifestation theory as a limitation on coverage. One of the first drafts, prepared by the Joint Drafting Committee in 1960, “would deem all of the injury to have occurred” at the first manifestation of injury or damage. That draft was sent back to the Drafting Committee by the higher level Joint Rating Committee, and Mr. Schmalz has testified without contradiction that this remand was a rejection by the task force leadership of the manifestation approach. Id. at 42, 64-65. The various committees rejected all other drafts that included a manifestation concept, see id. at 42; they found the concept unacceptable because, among other reasons, “it would permit a carrier to cancel following the first notice of injury and leave the insured without coverage for other injuries emerging from the same exposure,” and because in many cases injuries sufficiently serious to trigger coverage could occur prior to any form of manifestation. Memorandum: “Action of the Liability Rating Committee of the Mutual Bureau Meeting” (Sept. 12-14,1961), Pl.Ex. 25 at 1; see also Pl.Ex. 26 (Minutes of Meeting of Joint Scope of Coverage Subcommittee (Sept. 19-20, 1961)) at 3; Wrubel, supra, at 684-85. Manifestation-theory advocates argued that a nonmanifestation policy would permit insureds to pyramid the limits on policies that cover injuries caused by long-term exposure. See Schmalz Dep., Pl.Ex. 23 at 78-80. Rejection of the manifestation concept in the CGL was thus implicit in its drafters’ widespread recognition that the CGL would permit the insured to pyramid the limits of multiple policies when injuries occurred in more than one policy period. See, e.g., Elliott, The New Comprehensive General Liability Policy, in Liability Insurance Disputes 12-5 (S. Schreiber ed. 1968) (“In some exposure types of cases involving cumulative injuries, it is possible that more than one policy will afford coverage.”). Gilbert Bean, a Liberty officer who served on the Joint Rating Committee, distributed a memorandum to Liberty underwriters in July 1966 that explained how injuries could occur at different points under the CGL: Limits are rendered annually for gradual BI (bodily injury) or PD (property damage) from a single occurrence or common exposure to conditions, whether on the same or successive policies in one or more carriers. If the gradual BI or PD extends past one or more policy anniversary dates the limits will pyramid, whereas previously all injury or damage from one accident was attributed back to the policy during which the accident occurred. Pl.Ex. 29 at 3. Liberty contends that the history of the CGL cannot be relied upon by AHP, because material issues of fact exist as to what the task force intended. But Liberty has failed to raise a material issue of fact by offering evidence to contradict the view that the CGL drafters rejected the manifestation approach. On the other hand, Liberty correctly argues that the CGL’s history does not permit AHP to succeed on its claim that the task force adopted the exposure theory. Indeed, the evidence from the CGL drafting process is almost as clearly against an exposure theory as it is against manifestation. Once again, Mr. Schmalz casts important light on what occurred. Soon after the Joint Rating Committee remanded the draft incorporating a manifestation limitation to the Joint Drafting Committee, Schmalz circulated a memorandum to his colleagues reviewing alternatives to manifestation. One of his suggestions for dealing with continuous or repeated exposure situations was what he called the “contact with the means of injury” approach. Recognizing that the approach was “novel” for insurance coverage, he suggested specific language to implement the proposal, which would have provided insurance for any “physical contact with the means of injury” during a period of coverage, even if the actual injury did not result until much later. Def.Ex. 37 (Schmalz Memorandum); see Schmalz Dep., Def.Ex. 22 at 118-19. The Committee rejected this language, however, adopting instead the CGL’s coverage of any injury that results during the policy period, irrespective of when “the contact with the means of injury” — the exposure — took place. Mr. Schmalz’ own understanding of how the CGL was to operate lends strong support to the injury-in-fact approach suggested by the plain language. Schmalz believes that use of the insured’s product during the policy period should trigger coverage under the CGL, but only if the policyholder is able to show that injurious biological effects occurred each time the product was used. Consistent with the clear language of the CGL, Schmalz construes it to require, not only an exposure, but an exposure that injures; and whether an injury has occurred in a given case is a “medical fact question” to be resolved on an ad hoc basis for each product and malady involved. Schmalz Dep., Def.Ex. 22 at 84. Thus he acknowledges that, while in some cases exposure and CGL “injury” may coincide, in many cases they will not. See id. at 163-65. The insurance industry task force intended, he says, that the CGL policyholder carry the burden of proving that the injury at issue occurred during a period of coverage, id. at 110, and he repeatedly testified that the issue of when an injury occurs “is a matter to be determined on the basis of facts relating to medical issues as to when injury occurred and factual issues as to when exposure took place,” id. at 136-37, 151. Mr. Schmalz is not the only person involved in the process of writing the CGL who viewed coverage as depending upon injury-in-fact, rather than on either manifestation or exposure. For example, Richard Elliott, then Secretary of the National Bureau of Casualty Underwriters, in presenting what he described as “the underwriting intent” of the CGL’s revisers, explained that “the definition of occurrence serves to identify the time of loss for the purpose of applying coverage — the injury must take place during the policy period.” He recognized that long exposure could involve “cumulative injuries,” in which “more than one policy afford[s] coverage,” and “each policy will afford coverage to the bodily injury or property damage which occurs during the policy period.” Elliott, The New Comprehensive General Liability Policy, supra. Other contemporary explanations and analyses likewise state or assume that coverage under the CGL would require proof of injury during that period, not merely exposure and not necessarily manifestation. Thus, one commentator stated: “The policy will not depend upon the causative event of occurrence but will be based upon injuries or damages which result from such an event and which happened during the policy period. It will not be material whether the causative event happened during or before the policy period.” Obrist, The New Comprehensive General Liability Insurance Policy — A Coverage Analysis 6 (Defense Research I