Opinion
KENNARD, J.In 1995, the California Legislature found that “[tjobaccorelated disease places a tremendous financial burden upon the persons with the disease, their families, the health care delivery system, and society as a whole,” and that “California spends five billion six hundred million dollars ($5,600,000,000) a year in direct and indirect costs on smoking-related illnesses.” (Health & Saf. Code, § 104350, subd. (a)(7).) To obtain compensation for the physical and mental suffering and staggering expenses inflicted by tobacco-related illness, users of tobacco products and their families have sought relief in our courts through product liability lawsuits against manufacturers and sellers of tobacco products. In dealing with those lawsuits, courts have not been free to apply ordinary principles of tort law because, as we shall explain, the Legislature has enacted statutes that directly control the extent to which our courts may award damages against tobacco companies in product liability actions.
The statutes at issue are two successive versions of section 1714.45 of California’s Civil Code.1 The first version, which we here sometimes refer to as the Immunity Statute, granted tobacco companies complete immunity in *832certain product liability lawsuits as of January 1, 1988.2 (Added by Stats. 1987, ch. 1498, § 3, p. 5778.) The second version, which we here sometimes refer to as the Repeal Statute, rescinded that immunity 10 years later on January 1, 1998. (Stats. 1997, ch. 570, § 1.) The United States Court of Appeals for the Ninth Circuit has certified to us a question asking whether the Repeal Statute governs “a claim that accrued after January 1, 1998, but which is based on conduct that occurred prior to January 1, 1998.” (Myers v. Philip Morris Companies, Inc. (9th Cir. 2001) 239 F.3d 1029, 1030 (Myers).)
Our answer is this: The Immunity Statute applies to certain statutorily described conduct of tobacco companies that occurred during the 10-year immunity period, which began on January 1, 1988, and ended on December 31, 1997. With respect to such conduct, therefore, the statutory immunity applies, and no product liability cause of action may be based on that conduct, regardless of when the users of the tobacco products may have sustained or discovered injuries as a result of that conduct. That statutory immunity was rescinded, however, when the California Legislature enacted the Repeal Statute, which as of January 1, 1998, restored the general principles of tort law that had, until the 1988 enactment of the Immunity Statute, governed tort liability against tobacco companies. Therefore, with respect to conduct falling outside the 10-year immunity period, the tobacco companies are not shielded from product liability lawsuits.
I. Facts
The Court of Appeals for the Ninth Circuit described the background of this case as follows: “Betty Jean Myers began smoking cigarettes in 1956 and continued to smoke heavily until 1997. Throughout this period, and until August of 1998, she also worked and lived in environments in which those around her smoked cigarettes. On April 8, 1998, Myers was diagnosed with lung cancer allegedly caused by her exposure to tobacco. On March 4, 1999, Myers filed a complaint in Tulare County Superior Court against Philip Morris and other defendant tobacco manufacturers (collectively, the ‘Tobacco Manufacturers’) alleging several claims, including strict liability, negligence, breach of implied warranties, fraud, and negligent misrepresentation.” (Myers, supra, 239 F.3d at p. 1030.)
The Ninth Circuit’s description continues: “After removing this case to the United States District Court for the Eastern District of California, the *833Tobacco Manufacturers moved, on April 13, 1999, to dismiss Myers’s complaint for failure to state a claim. On May 25, 1999, the district court granted the motion to dismiss, with leave to amend, on the ground that Cal. Civ. Code § 1714.45 barred Myers’s actions for any injuries incurred prior to January 1998. On June 30, 1999, Myers amended her complaint to allege that she was exposed to secondhand cigarette smoke between January 1, 1998 and April 8, 1998. On July 19, 1999, the Tobacco Manufacturers again moved to dismiss Myers’s complaint for failure to state a claim. On October 6, 1999, the district court again dismissed Myers’s complaint for failure to state [a] claim, this time without leave to amend, on the grounds that she had conceded that her lung cancer was not caused by her exposure to secondhand smoke after January 1, 1998, and, again, that pre-1998 exposures were not actionable. Myers filed a timely notice of appeal to the Ninth Circuit.” (Myers, supra, 239 F.3d at p. 1031.)
II. Background
We start with a review of the Immunity Statute and two California cases that have construed that statute, American Tobacco Co. v. Superior Court (1989) 208 Cal.App.3d 480 [255 Cal.Rptr. 280], a decision of the state Court of Appeal, and Richards v. Owens-Illinois, Inc. (1997) 14 Cal.4th 985 [60 Cal.Rptr.2d 103, 928 P.2d 1181], a decision of this court.
A. The Immunity Statute
Enacted as part of the Willie L. Brown, Jr.—Bill Lockyer Civil Liability Reform Act of 1987, former section 1714.45 (the Immunity Statute) provided in full:
“(a) In a product liability action, a manufacturer or seller shall not be liable if:
“(1) The product is inherently unsafe and the product is known to be unsafe by the ordinary consumer who consumes the product with the ordinary knowledge common to the community; and
“(2) The product is a common consumer product intended for personal consumption, such as sugar, castor oil, alcohol, tobacco, and butter, as identified in comment i to Section 402A of the Restatement (Second) of Torts.
“(b) For purposes of this section, the term ‘product liability action’ means any action for injury or death caused by a product, except that the term does *834not include, an action based on a manufacturing defect or breach of an express warranty.
“(c) This section is intended to be declarative of and does not alter or amend existing California law, including Cronin v. J.B.E. Olson Corp., (1972) 8 Cal. 3d 121 [104 Cal. Rptr. 433, 501 P.2d 1153], and shall apply to all product liability actions pending on, or commenced after, January 1, 1988.” (Stats. 1987, ch. 1498, § 3, pp. 5778-5779, italics added.)
We now discuss the two California decisions that have interpreted the Immunity Statute.
1. American Tobacco Co. v. Superior Court
The state Court of Appeal’s 1989 decision in American Tobacco Co. v. Superior Court, supra, 208 Cal.App.3d 480 (American Tobacco), which was authored by Presiding Justice J. Anthony Kline, was the first to construe the Immunity Statute. In that case, the court described the Immunity Statute as the result of a “ ‘peace pact’ ” or “compromise between parties seeking and opposing comprehensive changes in California tort law who had been locked in a long political struggle that had reached [a] stalemate.” (American Tobacco, supra, at pp. 486-487.) Those involved included major special interest groups such as insurers, physicians, manufacturers, and the plaintiff’s lawyers. (Id. at p. 486.)3 The Court of Appeal in American Tobacco characterized the Immunity Statute as so “poorly drafted” that “on its face[, it was] amenable to two diametrically opposed interpretations, each of which conflicted] in some way with the words” used by the Legislature. (American Tobacco, supra, at p. 485.) But legislative history, the court noted, indicated that the Immunity Statute’s intent was to ensure that “ ‘high-cholesterol foods, alcohol, and cigarettes that are inherently unsafe and known to be unsafe by ordinary consumers, [were] not to be subject to product liability lawsuits.’” (American Tobacco, supra, at p. 487, italics added.) In light of that legislative intent, the Court of Appeal in American Tobacco concluded that the statutory immunity was very broad, providing “nearly complete” immunity for manufacturers and sellers of tobacco and the other enumerated products. (Ibid.)
*8352. Richards v. Owens-Illinois, Inc.
In 1997, some eight years after the Court of Appeal’s decision in American Tobacco, supra, 208 Cal.App.3d 480, we construed the Immunity Statute in Richards v. Owens-Illinois, Inc., supra, 14 Cal.4th 985 (Richards). Because Richards is central to answering the question the Ninth Circuit has certified to us, we discuss it in some detail.
The plaintiff in Richards, supra, 14 Cal.4th 985, was a former shipyard worker who sued several asbestos manufacturers, claiming that his exposure to asbestos fibers at various shipyard jobs had caused him to develop asbestosis, a severe respiratory injury. At trial, one asbestos manufacturer, defendant Owens-Illinois, Inc., presented evidence that the plaintiff had contributed to the development of his respiratory injury by smoking for more than 40 years. {Id. at p. 990.) The issue before this court was whether the trial court should have allowed Owens-Illinois to present its so-called tobacco company defense, which would have required the jury, in determining fault with respect to noneconomic damages (to compensate the plaintiff for pain and suffering), to apportion to tobacco companies some percentage of fault, thereby reducing the percentage of the noneconomic damages award attributable to Owens-Illinois. (Id. at p. 991.)
To decide this question, we considered the interplay between the Immunity Statute and section 1431 et seq., enacted by the California electorate in an initiative known as Proposition 51. Proposition 51 provided in part that “in a tort action governed by principles of comparative fault, a defendant shall not be jointly liable for the plaintiffs ‘non-economic damages,’ but shall only be severally liable for such damages ‘in direct proportion to that defendant’s percentage of fault.’” (Richards, supra, 14 Cal.4th at p. 988, quoting § 1431.2, subd. (a).) The specific question we addressed in Richards was this: “To the extent [the Immunity Statute] protects tobacco companies from direct ‘liability]’ for harm caused by smoking, does it also preclude the allocation of proportionate ‘fault’ to absent tobacco companies in a smoker’s suit for asbestos-related lung injury, in order to reduce the ‘non-economic’ damages payable by the asbestos defendant under Proposition 51?” (Richards, supra, 14 Cal.4th at p. 988.)
We explained: “Though the [Immunity Statute] states only an exemption from direct ‘liability]’ where specified conditions are met, the express premise which justifies this immunity is of a broader nature. This premise is that suppliers of certain products which are ‘inherently unsafe,’ but which the public wishes to have available despite awareness of their dangers, should not be responsible in tort for resulting harm to those who voluntarily *836consumed the products despite such knowledge. With respect to injuries meeting the statute’s requirements, that principle precludes the assignment of legal ‘fault’ to such suppliers in all contexts, including suits from which they are absent by law.” (Richards, supra, 14 Cal.4th at p. 1002, italics added, original italics omitted.)
We pointed out that the Immunity Statute drew “its express inspiration from product liability principles” set forth in comment i to section 402A of the Restatement Second of Torts (Restatement), and these principles provided the premise for the statute. (Richards, supra, 14 Cal.4th at p. 999.)
We observed: “Section 402A of the Restatement proposes generally that when a manufacturer or distributor sells a product ‘in a defective condition unreasonably dangerous to the user or consumer’ ([Rest.] p. 347, italics added), and the product reaches that person, as expected and intended, without substantial change in its condition, the seller is ‘subject to liability’ for physical harm ‘thereby caused to the ultimate user or consumer.’ [f] However, comment i asserts an important qualification of the general rule . . . . [It] makes clear that. . . ‘[t]he rule [of liability] applies only where the defective condition of the product makes it unreasonably dangerous to the user or consumer.’ (Restatement, p. 352, italics added.) As comment i then explains, ‘[m]any products cannot possibly be made entirely safe for all consumption,’ but if a product is pure and unadulterated, its inherent or unavoidable danger, commonly known to the community which consumes it anyway, does not expose the seller to liability for resulting harm to a voluntary user.” (Richards, supra, 14 Cal.4th at p. 999.)
Richards added: “The clear premise of comment i is that no ‘liability’ arises [for the manufacture or distribution of a product that in its pure and unadulterated form poses for its voluntary users an inherent and unavoidable danger] because there is no sound basis for liability. In other words, comment i posits, a manufacturer or seller breaches no legal duty to voluntary consumers by merely supplying, in unadulterated form, a common commodity which cannot be made safer, but which the public desires to buy and ingest despite general understanding of its inherent dangers.” (Richards, supra, 14 Cal.4th at p. 1000.)
Because it would have been “anomalous” for a supplier of tobacco products, “though immunized . . . from direct liability for providing an ‘inherently unsafe’ product to a knowing and voluntary consumer . . . [to] nonetheless be assigned ‘fault’ for doing so in an action between that same consumer and a third party defendant,” we held in Richards “that to the extent [the Immunity Statute] afford[ed] tobacco suppliers immunity from *837liability]’ in direct actions against them, on grounds that the immunized conduct breache[d\ no duty and constitute[d\ no tort, the statute also preclude [d] indirect assignment of comparative ‘fault’ ... to such entities for purposes of Proposition 51.” (Richards, supra, 14 Cal.4th at pp. 1000-1001, italics added.)
In short, our unanimous decision in Richards, supra, 14 Cal.4th 985, made clear that between January 1, 1988, and December 31, 1997, when the Immunity Statute was in effect, supplying pure and unadulterated tobacco products to knowing and voluntary consumers of those products was not subject to tort liability because it breached no legal duty and thus constituted no tort.
B. The Repeal Statute
Ten years after enactment of the Immunity Statute and some eight months after our decision in Richards, supra, 14 Cal.4th 985, the California Legislature enacted the Repeal Statute, which amended former section 1714.45 to rescind the statutory immunity for tobacco companies as of January 1, 1998.4 When enacted, the Repeal Statute provided, and with one minor change still provides:
“(a) In a product liability action, a manufacturer or seller shall not be liable if both of the following apply:
“(1) The product is inherently unsafe and the product is known to be unsafe by the ordinary consumer who consumes the product with the ordinary knowledge common to the community.
“(2) The product is a common consumer product intended for personal consumption, such as sugar, castor oil, alcohol, and butter, as identified in comment i to Section 402A of the Restatement (Second) of Torts.
“(b) This section does not exempt the manufacture or sale of tobacco products by tobacco manufacturers and their successors in interest from product liability actions, but does exempt the sale or distribution of tobacco *838products by any other person, including, but not limited to, retailers or distributors.
“(c) For purposes of this section, the term ‘product liability action’ means any action for injury or death caused by a product, except that the term does not include an action based on a manufacturing defect or breach of an express warranty.
“(d) This section is intended to be declarative of and does not alter or amend existing California law, including Cronin v. J.B.E. Olson Corp., (1972), 8 Cal. 3d 121, and shall apply to all product liability actions pending on, or commenced after, January 1, 1988.
“(e) This section does not apply to, and never applied to, an action brought by a public entity to recover the value of benefits provided to individuals injured by a tobacco-related illness caused by the tortious conduct of a tobacco company or its successor in interest, including, but not limited to, an action brought pursuant to Section 14124.71 of the Welfare and Institutions Code. In such an action brought by a public entity, the fact that the injured individual’s claim against the defendant may be barred by a prior version of this section shall not be a defense. This subdivision does not constitute a change in, but is declaratory of, existing law relating to tobacco products.
“(f) It is the intention of the Legislature in enacting the amendments to subdivisions (a) and (b) of this section adopted at the 1997-98 Regular Session to declare that there exists no statutory bar to tobacco-related personal injury, wrongful death, or other tort claims against tobacco manufacturers and their successors in interest by California smokers or others who have suffered or incurred injuries, damages, or costs arising from the promotion, marketing, sale, or consumption of tobacco products. It is also the intention of the Legislature to clarify that such claims which were or are brought shall be determined on their merits, without the imposition of any claim of statutory bar or categorical defense.
“(g) This section shall not be construed to grant immunity to a tobacco industry research organization.” (§ 1714.45, as amended by Stats. 1997, ch. 570, § 1, italics added.)5
Through subdivisions (b) and (f), the Repeal Statute expressly rescinded the statutory immunity from product liability lawsuits for tobacco companies *839that the Legislature had allowed 10 years earlier. Although the Repeal Statute retained the Immunity Statute’s reference to comment i to section 402A of the Restatement, negating liability to voluntary users of certain common but inherently unsafe consumer products, the Repeal Statute in subdivision (a) omitted tobacco products from specified “inherently unsafe” products.
III. Discussion
We now turn to the question that the Ninth Circuit has asked us to decide: “Do the amendments to Cal. Civ. Code § 1714.45 that became effective on January 1, 1998, apply to a claim that accrued after January 1, 1998, but which is based on conduct that occurred prior to January 1, 1998?” To answer this question we must determine how the Repeal Statute affects product liability suits against tobacco companies based on their activities as manufacturers and sellers of tobacco products before, during, and after the statutory immunity period.
In certifying the question, the Ninth Circuit noted plaintiffs contention that applying the Repeal Statute in her case would be a prospective rather than a retroactive application of that law because she was diagnosed with cancer on April 8, 1998, three months after January 1, 1998, the date on which the Repeal Statute took effect. We address that issue below.
A. Whether Applying the Repeal Statute to Defendant Tobacco Companies ’ Conduct During the Immunity Period Would Be a Prospective or a Retroactive Application of That Statute
As we said more than 50 years ago, a retroactive or retrospective law “ ‘is one which affects rights, obligations, acts, transactions and conditions which are performed or exist prior to the adoption of the statute.’ ” (Aetna Cas. & Surety Co. v. Ind. Acc. Com. (1947) 30 Cal.2d 388, 391 [182 P.2d 159]; accord, Evangelatos v. Superior Court (1988) 44 Cal.3d 1188, 1206 [246 Cal.Rptr. 629, 753 P.2d 585] (Evangelatos).) Similarly, the United States Supreme Court has stated: ‘“[E]very statute, which takes away or impairs vested rights acquired under existing laws, or creates a new obligation, imposes a new duty, or attaches a new disability, in respect to transactions or considerations already past, must be deemed retrospective.’ ” (Landgraf v. USI Film Products (1994) 511 U.S. 244, 269 [114 S.Ct. 1483, 1499, 128 L.Ed.2d 229].) Phrased another way, a statute that operates to “increase a party’s liability for past conduct” is retroactive. (Id. at p. 280 [114 S.Ct. at p. 1505]; Evangelatos, supra, 44 Cal.3d at p. 1206.)
*840As we explained earlier, while the Immunity Statute was in effect—from January 1, 1988, through December 31, 1997—no tortious liability attached to a tobacco company’s production and distribution of pure and unadulterated tobacco products to smokers. (Former § 1714.45, as added by Stats. 1987, ch. 1498, § 3, p. 5778; Richards, supra, 14 Cal.4th at p. 1001.) But on January 1, 1998, the California Legislature, through its enactment of the Repeal Statute, terminated that statutory immunity. (§ 1714.45.) Here, plaintiff started smoking in 1956 and, some 41 years later, quit smoking in 1997. But during 10 of those 41 years, from January 1, 1988, to December 31, 1997, because of the Immunity Statute, the manufacture and sale of covered products were not tortious. Accordingly, to have the Repeal Statute govern product liability suits against tobacco companies for supplying tobacco products to smokers during the immunity period would indeed be a retroactive application of that statute because it could subject those companies to “liability for past conduct” (Landgraf v. USI Film Products, supra, 511 U.S. at p. 280 [114 S.Ct. at p. 1505]; see also Evangelatos, supra, 44 Cal.3d at p. 1206) that was lawful during the immunity period (Richards, supra, 14 Cal.4th at p. 1001). Such retroactive application is impermissible unless there is an express intent of the Legislature to do so. We explore that issue below.
B. Whether the California Legislature Expressed an Intent That the Repeal Statute Govern Tobacco Companies ’ Liability During the Immunity Period
Generally, statutes operate prospectively only. In the words of section 3 of California’s Civil Code: “No part of [this code] is retroactive, unless expressly so declared.” (Italics added.) The Ninth Circuit, in certifying the question to us, cited our decision in Evangelatos, supra, 44 Cal.3d at page 1208, when noting defendant tobacco companies’ contention that “a retroactive application [of a statute] requires either ‘express language or clear and unavoidable implication’ from the California Legislature.” {Myers, supra, 239 F.3d at p. 1032.) On that point, defendants are right. We explained in Evangelatos: “ ‘ “[T]he first rule of [statutory] construction is that legislation must be considered as addressed to the future, not to the past. . . . The rule has been expressed in varying degrees of strength but always of one import, that a retrospective operation will not be given to a statute which interferes with antecedent rights . . . unless such be ‘the unequivocal and inflexible import of the terms, and the manifest intention of the legislature.’ ” ’ ” {Evangelatos, supra, 44 Cal.3d at p. 1207, quoting United States v. Security Industrial Bank (1982) 459 U.S. 70, 78-79 [103 S.Ct. 407, 412-413, 74 L.Ed.2d 235], italics omitted.) In the words of the United States Supreme Court, “the ‘principle that the legal effect of conduct *841should ordinarily be assessed under the law that existed when the conduct took place has timeless and universal appeal.’ ” (Landgraf v. USI Film Products, supra, 511 U.S. at p. 265 [114 S.Ct. at p. 1497]; accord, Hughes Aircraft Co. v. United States ex rel. Schumer (1997) 520 U.S. 939, 946 [117 S.Ct. 1871, 1876, 138 L.Ed.2d 135].)
As the United States Supreme Court has consistently stressed, the presumption that legislation operates prospectively rather than retroactively is rooted in constitutional principles: “In a free, dynamic society, creativity in both commercial and artistic endeavors is fostered by a rule of law that gives people confidence about the legal consequences of their actions. [U] It is therefore not surprising that the antiretroactivity principle finds expression in several provisions of our Constitution. The Ex Post Facto Clause flatly prohibits retroactive application of penal legislation. . . . The Fifth Amendment’s Takings Clause [, and] [t]he Due Process Clause also protect[] the interests in fair notice and repose that may be compromised by retroactive legislation; a justification sufficient to validate a statute’s prospective application under the [Due Process] Clause ‘may not suffice’ to warrant its retroactive application.” (Landgraf v. USI Film Products, supra, 511 U.S. at pp. 265-266 [114 S.Ct. at p. 1497], italics added; accord, INS v. St. Cyr (2001) 533 U.S. 289, 316 [121 S.Ct. 2271, 2288, 150 L.Ed.2d 347].)
Just as federal courts apply the time-honored legal presumption that statutes operate prospectively “unless Congress has clearly manifested its intent to the contrary” (Hughes Aircraft Co. v. United States ex rel. Schumer, supra, 520 U.S. at p. 946 [117 S.Ct. at p. 1876]), so too California courts comply with the legal principle that unless there is an “express retroactivity provision, a statute will not be applied retroactively unless it is very clear from extrinsic sources that the Legislature ... must have intended a retroactive application” (Evangelatos, supra, 44 Cal.3d at p. 1209, italics added). California courts apply the same “general prospectivity principle” as the United States Supreme Court. (Id. at p. 1208.) Under this formulation, a statute’s retroactivity is, in the first instance, a policy determination for the Legislature and one to which courts defer absent “some constitutional objection” to retroactivity. (Western Security Bank v. Superior Court (1997) 15 Cal.4th 232, 244 [62 Cal.Rptr.2d 243, 933 P.2d 507].) But “a statute that is ambiguous with respect to retroactive application is construed . . . to be unambiguously prospective.” (INS v. St. Cyr, supra, 533 U.S. atpp. 320-321, fn. 45 [121 S.Ct. at p. 2290]; Lindh v. Murphy (1997) 521 U.S. 320, 328, fn. 4 [117 S.Ct. 2059, 2064, 138 L.Ed.2d 481] [“ ‘retroactive’ effect adequately authorized by a statute” only when statutory language was “so clear that it could sustain only one interpretation”].)
*8421. Repeal Statute has no express retroactivity language
In contending that the Repeal Statute is not retroactive, defendant tobacco companies contrast it with other California statutes that our Legislature has expressly made retroactive. (See § 1646.5 [“This section applies to contracts . . . entered into before, on, or after its effective date; it shall be fully retroactive . . .” (italics added)]; Gov. Code, § 9355.8 [“This section shall have retroactive application . . .” (italics added)].)
In addition, defendants point to language in the Repeal Statute’s subdivision (e) as a clear indication that the Legislature did not intend the Repeal Statute to be retroactive. (§ 1714.45, subd. (e).) That provision incorporates the substance of an earlier amendment to the Immunity Statute, the Public Entity Amendment (see fn. 4, ante), which was intended to allow public entities to sue tobacco companies notwithstanding the statutory immunity. When first enacted, the Public Entity Amendment added to the Immunity Statute a provision, subdivision (d), which stated that in an “action brought by a public entity, the fact that the injured individual’s claim against the defendant may be barred by this section shall not be a defense.” (Former § 1714.45, subd. (d), as added by Stats. 1997, ch. 25, § 2, italics added.) But when that provision became subdivision (e) of the Repeal Statute, the Legislature rephrased it to state that a public entity’s suit against a tobacco company would not be precluded by “the fact that the injured individual’s claim against the defendant may be barred by a prior version of this section.” (§ 1714.45, subd. (e), as added by Stats. 1997, ch. 570, § 1, italics added.) The italicized language suggests that even after the January 1, 1998, effective date of the Repeal Statute, “a prior version” of that statute, namely the Immunity Statute, may continue to bar claims against tobacco companies brought by individual smokers.
Plaintiff insists that certain phrases in the Repeal Statute are express legislative declarations of retroactivity notwithstanding the absence of the term “retroactive” in that provision. When enacted, subdivision (f) of the Repeal Statute provided: “It is the intention of the Legislature in enacting the amendments to subdivisions (a) and (b) of this section adopted at the 1997-98 Regular Session to declare that there exists no statutory bar to tobacco-related personal injury, wrongful death, or other tort claims against tobacco manufacturers and their successors in interest by California smokers or others who have suffered or incurred injuries, damages, or costs arising from the promotion, marketing, sale, or consumption of tobacco products. It is also the intention of the Legislature to clarify that such claims which were or are brought shall be determined on their merits, without the imposition of any claim of statutory bar or categorical defense.” (§ 1714.45, subd. (f), as added by Stats. 1997, ch. 570, § 1, italics added.)
*843Focusing on the italicized phrases in isolation, plaintiff asserts, as does the dissent, that they are express declarations of the California Legislature’s intent to retroactively apply the statute repealing the tobacco companies’ immunity from products liability lawsuits brought by smokers. We are not persuaded. Neither the italicized phrases nor section 1714.45, subdivision (f) as a whole states anything more than that the Repeal Statute rescinded any former statutory immunity for tobacco companies. But even were we to accept that proposed reading of subdivision (f), the Repeal Statute is, at best, ambiguous on the question of retroactivity because of the Legislature’s reference in subdivision (e) (allowing public entities to sue tobacco companies) to “a prior version” of the statute as possibly precluding suits against tobacco companies by individual smokers. This ambiguity requires us to construe the Repeal Statute as “unambiguously prospective.” (INS v. St. Cyr, supra, 533 U.S. at pp. 320-321, fn. 45 [121 S.Ct. at p. 2290].)
Furthermore, the time-honored presumption against retroactive application of a statute, as reflected in section 3 of the California Civil Code as well as in decisions by this court and the United States Supreme Court, would be meaningless if the vague phrases relied on by plaintiff and the dissent were considered sufficient to satisfy the test of a “clear[] manifest[ation]” (Hughes Aircraft Co. v. United States ex rel. Schumer, supra, 520 U.S. at p. 946 [117 S.Ct. at p. 1876]) or an “‘“‘unequivocal and inflexible””” assertion (Evangelatos, supra, 44 Cal.3d at p. 1207, italics omitted) of the Repeal Statute’s retroactivity. After a painstaking review of the entire Repeal Statute, we find it to be devoid of any express legislative intent of retroactivity. Although we agree with the dissent that “no talismanic word or phrase is required to establish retroactivity” (dis. opn. of Moreno, J., post, at p. 849), we do not agree there is language in the Repeal Statute of the unequivocal and inflexible statement of retroactivity that Evangelatos requires.
Interestingly, the Attorney General, in his role as amicus curiae for plaintiff, does not join plaintiff in urging this court to construe the Repeal Statute as retroactive. Instead, in an effort to avoid “the constitutional concerns inherent in retroactive laws,” the Attorney General argues that the Immunity Statute did nothing more than codify the common law defense of assumption of risk, a statutory defense that the Legislature, by its enactment of the Repeal Statute effective January 1, 1998, eliminated for all trials after that date.
The Attorney General’s argument disregards the logical basis of this court’s 1997 decision in Richards, supra, 14 Cal.4th 985, 1001, which construed the Immunity Statute not as codifying an existing affirmative defense for trial but as declaring legally permissible and not wrongful certain *844conduct of tobacco companies. Applying Richards here, we reject the Attorney General’s interpretation of the Immunity Statute.
2. Extrinsic sources provide no clear indication of legislative intent to apply the Repeal Statute retroactively
In contending that the Repeal Statute’s legislative history is a “very clear” indicator that the California Legislature intended the statute to apply retroactively, plaintiff points to a brief comment in a report of the Senate Judiciary Committee prepared for the April 8, 1997, hearing on the bill to enact the Repeal Statute. The comment appears under the heading “Prospective repeal only” and states: “Some concern has been expressed that [Senate Bill No.] 67 would apply only to causes of action arising on or after January 1, 1998, assuming it is enacted this year. In the absence of specific language in the legislation specifying retroactive application, a measure will operate prospectively only. . . .” (Sen. Com. on Judiciary, Rep. on Sen. Bill No. 67 (1997-1998 Reg. Sess.) Apr. 8, 1997, p. 3.) Plaintiff observes that just eight days later, an amendment added to the bill language stating that “there exists no statutory bar to . . . tobacco-related personal injury, wrongful death, or other tort claims by California smokers or others who have suffered or incurred injuries,” and indicating “that such claims which were or are brought’ should be determined on their merits. (Sen. Bill No. 67 (1997-1998 Reg. Sess.) as amended Apr. 16, 1997, italics added; now § 1714.45, subd. (f).) Plaintiff characterizes this amendment as the Legislature’s “direct response” to the expressed “concern” about retroactivity, and thus as comprising a “very clear” indication that the Repeal Statute was to apply retroactively. We are not persuaded.
As we observed earlier, a statute may be applied retroactively only if it contains express language of retroactivity or if other sources provide a clear and unavoidable implication that the Legislature intended retroactive application. (Evangelatos, supra, 44 Cal.3d at p. 1208.) Addressing in this section the latter ground, we conclude that plaintiff has not shown a clear and unavoidable implication of legislative intent to apply the Repeal Statute retroactively. The committee report that plaintiff cites merely states the general rule that legislation operates prospectively unless there is clear language of retroactivity; nothing in that report indicates that the Legislature desired retroactive application of the Repeal Statute. The April 16, 1997, bill amendment adding language to subdivision (f) of the Repeal Statute does not cure this omission, because the added language does not itself supply an unavoidable implication that the Legislature intended to subject tobacco companies to potential tort liability for conduct occurring during the 10-year period when the Immunity Statute declared that very conduct to be lawful. *845Its addition to the Repeal Statute eight days after some unspecified person voiced concern about retroactivity suggests that subdivision (f) may have been “the product of a legislative compromise” (Fremont Comp. Ins. Co. v. Superior Court (1996) 44 Cal.App.4th 867, 874 [52 Cal.Rptr.2d 211]), a way for legislators with differing views on retroactivity to vote for the Repeal Statute. “Avoiding resolution of disputed points is one of the classic means by which legislators are able to achieve agreement on legislative text.” (Id. at pp. 873-874; accord, J.A. Jones Construction Co. v. Superior Court (1994) 27 Cal.App.4th 1568, 1577 [33 Cal.Rptr.2d 206].)
Plaintiff also points to comments by the Repeal Statute’s author that “tobacco companies may have deliberately manipulated the level of nicotine” in tobacco products and “waged an aggressive campaign of disinformation about the health consequences of tobacco use.” (Sen. Com. on Judiciary, Rep. on Sen. Bill No. 67 (1997-1998 Reg. Sess.) Apr. 8, 1997, p. 2.) According to plaintiff, these comments reflect the Legislature’s intent to remedy “past fraud” by tobacco companies by making the Repeal Statute retroactive. Not so.
Those comments were simply reasons given “in support of repeal” of the statutory immunity for tobacco companies (Sen. Com. on Judiciary, Rep. on Sen. Bill No. 67 (1997-1998 Reg. Sess.) Apr. 8, 1997, p. 2); they did not at all address retroactivity of the Repeal Statute. Moreover, we have repeatedly declined to discern legislative intent from comments by a bill’s author because they reflect only the views of a single legislator instead of those of the Legislature as a whole. (Quinterno v. Mercury Casualty Co. (1995) 11 Cal.4th 1049, 1062 [48 Cal.Rptr.2d 1, 906 P.2d 1057]; Grupe Development Co. v. Superior Court (1993) 4 Cal.4th 911, 922 [16 Cal.Rptr.2d 226, 844 P.2d 545] .)6
3. Constitutional considerations reinforce our reading of the Repeal Statute as not having retroactive application
Earlier we discussed the constitutional underpinnings of the presumption against a statute’s retroactive application. That presumption has particular force in this case, in which retroactive application of the California Legislature’s repeal of tobacco companies’ statutory immunity from *846product liability lawsuits could expose them to huge monetary damages for conduct that occurred during the statutory immunity period when that conduct carried no tort liability.
Instructive on this point is the United States Supreme Court’s recent decision in Eastern Enterprises v. Apfel (1998) 524 U.S. 498 [118 S.Ct. 2131, 141 L.Ed.2d 451] (Apfel), in which the high court invalidated a federal law that retroactively imposed on coal mining companies substantial financial obligations for the health care of their retired workers. In a plurality opinion, four of the nine justices concluded the law was an unconstitutional taking under the Fifth Amendment to the federal Constitution. (Apfel, supra, at p. 538 [118 S.Ct. at pp. 2153-2154] (plur. opn. of O’Connor, J.).) In his concurring opinion, Justice Kennedy concluded that the act violated the Fifth Amendment’s due process clause by retroactively creating liability for past conduct. (Apfel, supra, at p. 549 [118 S.Ct. at p. 2159] (cone. opn. of Kennedy, J.).) He observed: “If retroactive laws change the legal consequences of transactions long closed, the change can destroy the reasonable certainty and security which are the very objects of property ownership. As a consequence, due process protection for property must be understood to incorporate our settled tradition against retroactive laws of great severity. Groups targeted by retroactive laws, were they to be denied all protection, would have a justified fear that a government once formed to protect expectations now can destroy them. Both stability of investment and confidence in the constitutional system, then, are secured by due process restrictions against severe retroactive legislation.” (Id. at pp. 548-549 [118 S.Ct. at p. 2158] (cone. opn. of Kennedy, J.).)
In an earlier decision, Landgraf v. USI Film Products, supra, 511 U.S. 244, the high court questioned the constitutionality of legislation that retroactively would result in the imposition of punitive damages for particularly egregious conduct, suggesting it might violate the constitutional prohibition against ex post facto laws. (U.S. Const., art. I, § 9, cl. 3 [restricting federal government]; see also id., art. I, § 10, cl. 1 [restricting state governments]; Cal. Const., art. I, § 9.) In the words of the high court: “The very labels given ‘punitive’ or ‘exemplary’ damages, as well as the rationales that support them, demonstrate that they share key characteristics of criminal sanctions. Retroactive imposition of punitive damages would raise a serious constitutional question.” (Landgraf v. USI Film Products, supra, at p. 281 [114 S.Ct. at p. 1505].)
An established rule of statutory construction requires us to construe statutes to avoid “constitutional infirmities].” (United States v. Delaware & Hudson Co. (1909) 213 U.S. 366, 407-408 [29 S.Ct. 527, 535-536, 53 L.Ed. *847836]; United States v. Security Industrial Bank, supra, 459 U.S. 70, 78 [103 S.Ct. 407, 412]; see also Curran v. Mount Diablo Council of the Boy Scouts (1998) 17 Cal.4th 670, 727-728 [72 Cal.Rptr.2d 410, 952 P.2d 218] (cone, opn. of Kennard, J.).) That rule reinforces our construction of the Repeal Statute as prospective only.
C. Whether the Immunity Statute Precludes Recovery for Defendants ’ Conduct Before the Immunity Period
Plaintiff began smoking cigarettes in 1956 and continued to do so until 1997, a period of 41 years. For 10 years of this period—from January 1, 1988, through December 31, 1997—the Immunity Statute was in effect to shield tobacco companies from liability for personal injuries that their tobacco products caused to voluntary consumers. Because, as explained above, the Repeal Statute is not retroactive, plaintiff has no product liability claim against defendant tobacco companies for their conduct in manufacturing and distributing cigarettes during the statutory immunity period.
Regarding the portion of plaintiffs claim attributable to her use of cigarettes that defendant tobacco companies manufactured or distributed before the period of statutory immunity afforded those companies, defendants contend that the Immunity Statute shields them from liability. In support, they point out that the statute was expressly retroactive, covering during its effective period “all product liability actions pending on, or commenced after, January 1, 1988” (former § 1714.45, subd. (c), added by Stats. 1987, ch. 1498, § 3, p. 5779), whereas (as we hold here) the Repeal Statute was not retroactive and thus could not remove any of the protection conferred by the Immunity Statute. We reject defendants’ contention.
Although the Repeal Statute has no retroactive effect, it nonetheless removed the protection that the Immunity Statute gave to tobacco companies for their conduct occurring before the Immunity Statute’s effective date. This is so because a retroactive effect is one that “impairfs] rights a party possessed when he acted.” (Landgraf v. USI Film Products, supra, 511 U.S. at p. 280 [114 S.Ct. at p. 1505], italics added.) The Repeal Statute did not impair any rights that tobacco companies possessed before the immunity period. On the contrary, by abrogating the Immunity Statute, the Repeal Statute restored the law governing product liability for the manufacture or sale of tobacco products to what it had been before the January 1, 1988, effective date of the Immunity Statute.
Before January 1, 1988, general tort principles defined the extent of any tort liability that tobacco companies might have for manufacturing or distributing their tobacco products for sale to voluntary consumers. When, 10 *848years later, the California Legislature repealed the statutory immunity for tobacco manufacturers in product liability actions, it reinstated those general tort rules. This repeal did not “change the legal consequences” (Apfel, supra, 524 U.S. at p. 548 [118 S.Ct. at p. 2158]) of defendants’ conduct in manufacturing or distributing tobacco products before the effective date of the immunity. Nor could defendants reasonably have relied upon the Immunity Statute before its enactment. (See In re Marriage of Buol (1985) 39 Cal.3d 751, 761 [218 Cal.Rptr. 31, 705 P.2d 354].) Accordingly, repeal of the Immunity Statute eliminated any retroactive effect it may have had, so that the tort liability, if any, that defendants could incur for their conduct before the effective date of the Immunity Statute is determined by applying general tort principles.
IV. Conclusion
The Repeal Statute rescinding the tobacco companies’ statutory immunity in certain product liability lawsuits contains no express retroactivity provision. Nor has the Legislature given any clear indication that it wanted the Repeal Statute to apply retroactively. Thus, the Immunity Statute continues to shield defendant tobacco companies in product liability actions but only for conduct they engaged in during the 10-year period when the Immunity Statute was in effect. The liability of tobacco companies based on their conduct outside the 10-year period of immunity is governed by general tort principles. We stress, however, that we are not here asked to decide, and do not decide, what liability, if any, defendants may have under those general tort principles.
George, C. J., Baxter, J., Werdegar, J., Chin, J., and Brown, J., concurred.
Further undesignated statutory references are to the Civil Code.
As this court has done in prior cases discussing this legislation, we use the term “immunity” rather loosely, without restricting it to its narrowest technical meaning, that is, “a complete defense . . . [that] does not negate the tort.” (Black’s Law Dict. (1996 pocket ed.) p. 298; see also Delaney v. Superior Court (1990) 50 Cal.3d 785, 797, fn. 6 [268 Cal.Rptr. 753, 789 P.2d 934] [discussing the “immunity-privilege distinction”].)
The compromise agreement reportedly is known as “the ‘napkin deal’ since it was hammered out by political adversaries”—(one side “wanting comprehensive changes in California tort law, the other wanting to maintain the status quo”)—on a white cloth napkin in a Sacramento restaurant. (Moy, Tobacco Companies, Immune No More—California’s Removal of the Legal Barriers Preventing Plaintiffs From Recovering for Tobacco-related. Illness (1998) 29 McGeorge L.Rev. 761, 770.)
Earlier in the same legislative session, the California Legislature passed, as urgency legislation effective June 12,1997, Assembly Bill No. 1603 (1997-1998 Reg. Sess.) (hereafter the Public Entity Amendment). That bill amended the Immunity Statute to allow for “an action brought by a public entity to recover the value of benefits provided to individuals injured by a tobacco-related illness caused by the tortious conduct of a tobacco company.” (Former § 1714.45, subd. (d), as amended by Stats. 1997, ch. 25, § 2.) A third bill, regarding secondhand smoke (Sen. Bill No. 340 (1997-1998 Reg. Sess.)), was passed by the Legislature but vetoed by the Governor.
In 1998, the Legislature made nonsubstantive changes to the final sentence in subdivision (f) of the Repeal Statute. It now reads: “It is also the intention of the Legislature to clarify that those claims that were or are brought shall be determined on their merits, without the *839imposition of any claim of statutory bar or categorical defense.” (§ 1714.45, subd. (f), as amended by Stats. 1998, ch. 485, § 38, underscoring indicates changes.)
The dissent broadly asserts that these comments by the bill’s author and similar remarks in a letter supporting passage of the Repeal Statute “suggest” that the 1987 enactment of the statutory immunity was “secured in part by deceptive representations by the tobacco companies about the lethal nature of their product.” (Dis. opn. of Moreno, J., post, at p. 853 & fn. 2.) Neither these comments nor anything else in the record before us shows that the 1987 legislation was indeed a product of deception by tobacco companies. As an appellate court, we may not consider assertions of fact that are not supported by the record. (See People v. Szeto (1981) 29 Cal.3d 20, 35 [171 Cal.Rptr. 652, 623 P.2d 213].)