JUSTICE STEVENS delivered the opinion of the Court, except as to Parts V and VI.

"WARNING: THE SURGEON GENERAL HAS DETERMINED THAT CIGARETTE SMOKING IS DANGEROUS TO YOUR HEALTH." A federal statute enacted in 1969 requires that warning (or a variation thereof) to appear in a conspicuous place on every package of cigarettes sold in the United States. The questions presented to us by this case are whether that statute, or its 1965 predecessor which required a less alarming label, preempted petitioner's common-law claims against respondent cigarette manufacturers.

Petitioner's third amended complaint alleges several different bases of recovery, relying on theories of strict liability, negligence, express warranty, and intentional tort. These claims, all based on New Jersey law, divide into five categories. The "design defect claims" allege that respondents' cigarettes were defective because respondents failed to use a safer alternative design for their products and because the social value of their product was outweighed by the dangers it created. The "failure to warn claims" allege both that the product was "defective as a result of [respondents'] failure to provide adequate warnings of the health consequences of cigarette smoking" and that respondents "were negligent in the manner [that] they tested, researched, sold, promoted and advertised" their cigarettes. The "express warranty claims" allege that respondents had "expressly warranted that smoking the cigarettes which they manufactured and sold did not present any significant health consequences". The "fraudulent misrepresentation claims" allege that respondents had willfully, "through their advertising, attempted to neutralize the [federally mandated] warnin[g]" labels, and that they had possessed, but had "ignored and failed to act upon," medical and scientific data indicating that "cigarettes were hazardous to the health of consumers". Finally, the "conspiracy to defraud claims" allege that respondents conspired to deprive the public of such medical and scientific data.

As one of their defenses, respondents contended that the Federal Cigarette Labeling and Advertising Act, enacted in 1965, and its successor, the Public Health Cigarette Smoking Act of 1969, protected them from any liability based on their conduct after 1965. In a pretrial ruling, the District Court concluded that the federal statutes were intended to establish a uniform warning that would prevail throughout the country, and that would protect cigarette manufacturers from being "subjected to varying requirements from state to state," but that the statutes did not preempt common-law actions. Accordingly, the court granted a motion to strike the preemption defense entirely.

The Court of Appeals accepted an interlocutory appeal pursuant to 28 U.S.C. 1292(b), and reversed....
 

In 1964, the advisory committee issued its report, which stated as its central conclusion: "Cigarette smoking is a health hazard of sufficient importance in the United States to warrant appropriate remedial action." Relying in part on that report, the Federal Trade Commission (FTC), which had long regulated unfair and deceptive advertising practices in the cigarette industry, promulgated a new trade regulation rule. That rule, which was to take effect January 1, 1965, established that it would be a violation of the Federal Trade Commission Act "to fail to disclose, clearly and prominently, in all advertising and on every pack, box, carton, or container [of cigarettes] that cigarette smoking is dangerous to health and may cause death from cancer and other diseases."  Several States also moved to regulate the advertising and labeling of cigarettes. Upon a congressional request, the FTC postponed enforcement of its new regulation for six months. In July, 1965, Congress enacted the Federal Cigarette Labeling and Advertising Act (1965 Act or Act). The 1965 Act effectively adopted half of the FTC's regulation: the Act mandated warnings on cigarette packages ( 5(a)), but barred the requirement of such warnings in cigarette advertising ( 5(b)).

Section 2 of the Act declares the statute's two purposes: (1) adequately informing the public that cigarette smoking may be hazardous to health, and (2) protecting the national economy from the burden imposed by diverse, nonuniform, and confusing cigarette labeling and advertising regulations. In furtherance of the first purpose, 4 of the Act made it unlawful to sell or distribute any cigarettes in the United States unless the package bore a conspicuous label stating: "CAUTION: CIGARETTE SMOKING MAY BE HAZARDOUS TO YOUR HEALTH." In furtherance of the second purpose, 5, captioned "Preemption," provided in part: "(a) No statement relating to smoking and health, other than the statement required by section 4 of this Act, shall be required on any cigarette package. (b) No statement relating to smoking and health shall be required in the advertising of any cigarettes the packages of which are labeled in conformity with the provisions of this Act."

Although the Act took effect January 1, 1966, 10 of the Act provided that its provisions affecting the regulation of advertising would terminate on July 1, 1969.

As that termination date approached, federal authorities prepared to issue further regulations on cigarette advertising. It was in this context that Congress enacted the Public Health Cigarette Smoking Act of 1969 (1969 Act or Act), which amended the 1965 Act in several ways. First, the 1969 Act strengthened the warning label, in part by requiring a statement that cigarette smoking "is dangerous," rather than that it "may be hazardous." Second, the 1969 Act banned cigarette advertising in "any medium of electronic communication subject to [FCC] jurisdiction." Third, and related, the 1969 Act modified the preemption provision by replacing the original 5(b) with a provision that reads: (b) No requirement or prohibition based on smoking and health shall be imposed under State law with respect to the advertising or promotion of any cigarettes the packages of which are labeled in conformity with the provisions of this Act."
 

Congress' intent may be "explicitly stated in the statute's language or implicitly contained in its structure and purpose." In the absence of an express congressional command, state law is preempted if that law actually conflicts with federal law, or if federal law so thoroughly occupies a legislative field "`as to make reasonable the inference that Congress left no room for the States to supplement it.'"

In our opinion, the preemptive scope of the 1965 Act and the 1969 Act is governed entirely by the express language in 5 of each Act. When Congress has considered the issue of preemption and has included in the enacted legislation a provision explicitly addressing that issue, and when that provision provides a "reliable indicium of congressional intent with respect to state authority,  there is no need to infer congressional intent to preempt state laws from the substantive provisions" of the legislation. Such reasoning is a variant of the familiar principle of expression unius est exclusio alterius: Congress' enactment of a provision defining the preemptive reach of a statute implies that matters beyond that reach are not preempted. In this case, the other provisions of the 1965 and 1969 Acts offer no cause to look beyond 5 of each Act. Therefore, we need only identify the domain expressly preempted by each of those sections. As the 1965 and 1969 provisions differ substantially, we consider each in turn.
 

Beyond the precise words of these provisions, this reading is appropriate for several reasons. First, as discussed above, we must construe these provisions in light of the presumption against the preemption of state police power regulations. This presumption reinforces the appropriateness of a narrow reading of 5. Second, the warning required in 4 does not, by its own effect, foreclose additional obligations imposed under state law. That Congress requires a particular warning label does not automatically preempt a regulatory field. Third, there is no general, inherent conflict between federal preemption of state warning requirements and the continued vitality of state common-law damages actions.

This reading comports with the 1965 Act's statement of purpose, which expressed an intent to avoid "diverse, nonuniform, and confusing cigarette labeling and advertising regulations with respect to any relationship between smoking and health." Read against the backdrop of regulatory activity undertaken by state legislatures and federal agencies in response to the Surgeon General's report, the term "regulation" most naturally refers to positive enactments by those bodies, not to common-law damages actions.

The regulatory context of the 1965 Act also supports such a reading. As noted above, a warning requirement promulgated by the FTC and other requirements under consideration by the States were the catalyst for passage of the 1965 Act. These regulatory actions animated the passage of 5, which reflected Congress' efforts to prevent "a multiplicity of State and local regulations pertaining to labeling of cigarette packages," and to preemp[t] all Federal, State, and local authorities from requiring any statement relating to smoking and health in the advertising of cigarettes.

For these reasons, we conclude that 5 of the 1965 Act only preempted state and federal rulemaking bodies from mandating particular cautionary statements, and did not preempt state-law damages actions.
 

Notwithstanding these substantial differences in language, both petitioner and respondents contend that the 1969 Act did not materially alter the preemptive scope of federal law. Their primary support for this contention is a sentence in a Committee Report which states that the 1969 amendment "clarified" the 1965 version of 5(b). We reject the parties' reading as incompatible with the language and origins of the amendments. As we noted in another context, "[i]nferences from legislative history cannot rest on so slender a reed. Moreover, the views of a subsequent Congress form a hazardous basis for inferring the intent of an earlier one." The 1969 Act worked substantial changes in the law: rewriting the label warning, banning broadcast advertising, and allowing the FTC to regulate print advertising. In the context of such revisions and in light of the substantial changes in wording, we cannot accept the parties' claim that the 1969 Act did not alter the reach of 5(b).

Petitioner next contends that 5(b), however broadened by the 1969 Act, does not preempt common-law actions. He offers two theories for limiting the reach of the amended 5(b). First, he argues that common-law damages actions do not impose "requirement[s] or prohibition[s],"and that Congress intended only to trump "state statute[s], injunction[s], or executive pronouncement[s]." We disagree; such an analysis is at odds both with the plain words of the 1969 Act and with the general understanding of common-law damages actions. The phrase "[n]o requirement or prohibition" sweeps broadly, and suggests no distinction between positive enactments and common law; to the contrary, those words easily encompass obligations that take the form of common-law rules. As we noted in another context, "[state] regulation can be as effectively exerted through an award of damages as through some form of preventive relief. The obligation to pay compensation can be, indeed is designed to be, a potent method of governing conduct and controlling policy."

Although portions of the legislative history of the 1969 Act suggest that Congress was primarily concerned with positive enactments by States and localities, the language of the Act plainly reaches beyond such enactments. "We must give effect to this plain language unless there is good reason to believe Congress intended the language to have some more restrictive meaning."  In this case, there is no "good reason to believe" that Congress meant less than what it said; indeed, in light of the narrowness of the 1965 Act, there is "good reason to believe" that Congress meant precisely what it said in amending that Act.

Moreover, common-law damages actions of the sort raised by petitioner are premised on the existence of a legal duty, and it is difficult to say that such actions do not impose "requirements or prohibitions."  It is in this way that the 1969 version of 5(b) differs from its predecessor: whereas the common law would not normally require a vendor to use any specific statement on its packages or in its advertisements, it is the essence of the common law to enforce duties that are either affirmative requirements or negative prohibitions. We therefore reject petitioner's argument that the phrase "requirement or prohibition" limits the 1969 Act's preemptive scope to positive enactments by legislatures and agencies.

Petitioner's second argument for excluding common-law rules from the reach of 5(b) hinges on the phrase "imposed under State law." This argument fails as well. At least since Erie R. Co. v. Tompkins (1938), we have recognized the phrase "state law" to include common law as well as statutes and regulations....

That the preemptive scope of 5(b) cannot be limited to positive enactments does not mean that that section preempts all common-law claims. For example, as respondents concede, 5(b) does not generally preempt "state law obligations to avoid marketing cigarettes with manufacturing defects or to use a demonstrably safer alternative design for cigarettes." For purposes of 5(b), the common law is not of a piece.

Nor does the statute indicate that any familiar subdivision of common-law claims is or is not preempted. We therefore cannot follow petitioner's passing suggestion that 5(b) preempts liability for omissions, but not for acts, or that 5(b) preempts liability for unintentional torts, but not for intentional torts. Instead, we must fairly but - in light of the strong presumption against preemption - narrowly construe the precise language of 5(b), and we must look to each of petitioner's common-law claims to determine whether it is in fact preempted. The central inquiry in each case is straightforward: we ask whether the legal duty that is the predicate of the common-law damages action constitutes a requirement or prohibition based on smoking and health . . . imposed under State law with respect to . . . advertising or promotion, giving that clause a fair but narrow reading. As discussed below, each phrase within that clause limits the universe of common-law claims preempted by the statute.

We consider each category of damages actions in turn. In doing so, we express no opinion on whether these actions are viable claims as a matter of state law; we assume, arguendo, that they are.

Failure to Warn

To establish liability for a failure to warn, petitioner must show that "a warning is necessary to make a product . . . reasonably safe, suitable and fit for its intended use," that respondents failed to provide such a warning, and that that failure was a proximate cause of petitioner's injury. In this case, petitioner offered two closely related theories concerning the failure to warn: first, that respondents "were negligent in the manner [that] they tested, researched, sold, promoted, and advertised" their cigarettes; and second, that respondents failed to provide "adequate warnings of the health consequences of cigarette smoking."

Petitioner's claims are preempted to the extent that they rely on a state-law "requirement or prohibition . . . with respect to . . . advertising or promotion." Thus, insofar as claims under either failure-to-warn theory require a showing that respondents' post-1969 advertising or promotions should have included additional, or more clearly stated, warnings, those claims are preempted. The Act does not, however, preempt petitioner's claims that rely solely on respondents' testing or research practices or other actions unrelated to advertising or promotion.

Breach of Express Warranty

A manufacturer's liability for breach of an express warranty derives from, and is measured by, the terms of that warranty. Accordingly, the "requirement[s]" imposed by an express warranty claim are not "imposed under State law," but rather imposed by the warrantor. If, for example, a manufacturer expressly promised to pay a smoker's medical bills if she contracted emphysema, the duty to honor that promise could not fairly be said to be "imposed under state law," but rather is best understood as undertaken by the manufacturer itself. While the general duty not to breach warranties arises under state law, the particular "requirement . . . based on smoking and health . . . with respect to the advertising or promotion [of] cigarettes" in an express warranty claim arises from the manufacturer's statements in its advertisements. In short, a common-law remedy for a contractual commitment voluntarily undertaken should not be regarded as a "requirement . . . imposed under State law" within the meaning of 5(b).

Accordingly, to the extent that petitioner has a viable claim for breach of express warranties made by respondents, that claim is not preempted by the 1969 Act.

Fraudulent Misrepresentation

Petitioner alleges two theories of fraudulent misrepresentation. First, petitioner alleges that respondents, through their advertising, neutralized the effect of federally mandated warning labels. Such a claim is predicated on a state-law prohibition against statements in advertising and promotional materials that tend to minimize the health hazards associated with smoking. Such a prohibition, however, is merely the converse of a state-law requirement that warnings be included in advertising and promotional materials. Section 5(b) of the 1969 Act preempts both requirements and prohibitions; it therefore supersedes petitioner's first fraudulent misrepresentation theory.

Petitioner's second theory, as construed by the District Court, alleges intentional fraud and misrepresentation both by "false representation of a material fact [and by] conceal[ment of] a material fact."  The predicate of this claim is a state-law duty not to make false statements of material fact or to conceal such facts. Our preemption analysis requires us to determine whether such a duty is the sort of requirement or prohibition proscribed by 5(b).

Section 5(b) preempts only the imposition of state-law obligations "with respect to the advertising or promotion" of cigarettes. Petitioner's claims that respondents concealed material facts are therefore not preempted insofar as those claims rely on a state-law duty to disclose such facts through channels of communication other than advertising or promotion. Thus, for example, if state law obliged respondents to disclose material facts about smoking and health to an administrative agency, 5(b) would not preempt a state law-claim based on a failure to fulfill that obligation.

Moreover, petitioner's fraudulent misrepresentation claims that do arise with respect to advertising and promotions (most notably claims based on allegedly false statements of material fact made in advertisements) are not preempted by 5(b)....

Conspiracy to Misrepresent or Conceal Material Facts

Petitioner's final claim alleges a conspiracy among respondents to misrepresent or conceal material facts concerning the health hazards of smoking. The predicate duty underlying this claim is a duty not to conspire to commit fraud. For the reasons stated in our analysis of petitioner's intentional fraud claim, this duty is not preempted by 5(b), for it is not a prohibition "based on smoking and health" as that phrase is properly construed. Accordingly, we conclude that the 1969 Act does not preempt petitioner's conspiracy claim.

JUSTICE BLACKMUN, with whom JUSTICE KENNEDY and JUSTICE SOUTER join, concurring in part, concurring in the judgment in part, and dissenting in part.

The Court today would craft a compromise position concerning the extent to which federal law preempts persons injured by cigarette manufacturers' unlawful conduct from bringing state common law damages claims against those manufacturers. I, however, find the Court's divided holding with respect to the original and amended versions of the federal statute entirely unsatisfactory. Our precedents do not allow us to infer a scope of preemption beyond that which clearly is mandated by Congress' language. In my view, neither version of the federal legislation at issue here provides the kind of unambiguous evidence of congressional intent necessary to displace state common law damages claims....

The principles of federalism and respect for state sovereignty that underlie the Court's reluctance to find preemption where Congress has not spoken directly to the issue apply with equal force where Congress has spoken, though ambiguously. In such cases, the question is not whether Congress intended to preempt state regulation, but to what extent. We do not, absent unambiguous evidence, infer a scope of preemption beyond that which clearly is mandated by Congress' language. I therefore agree with the Court's unwillingness to conclude that the state common law damages claims at issue in this case are preempted unless such result is "`the clear and manifest purpose of Congress.'"

The plurality premises its preemption ruling on what it terms the "substantial changes" wrought by Congress in 5(b),  notably, the rewording of the provision to preempt any "requirement or prohibition" (as opposed merely to any "statement") "imposed under State law." As an initial matter, I do not disagree with the plurality that the phrase "State law," in an appropriate case, can encompass the common law as well as positive enactments such as statutes and regulations. I do disagree, however, with the plurality's conclusion that "State law" as used in 5(b) represents such an all-inclusive reference. Congress' intention in selecting that phrase cannot be understood without considering the narrow range of actions - any "requirement or prohibition" - that Congress specifically described in 5(b) as "imposed under" state law.

Although the plurality flatly states that the phrase "no requirement or prohibition" "sweeps broadly" and "easily encompass[es] obligations that take the form of common-law rules," those words are in reality far from unambiguous, and cannot be said clearly to evidence a congressional mandate to preempt state common law damages actions. The dictionary definitions of these terms suggest, if  anything, specific actions mandated or disallowed by a formal governing authority....

Finally, there is absolutely no suggestion in the legislative history that Congress intended to leave plaintiffs who were injured as a result of cigarette manufacturers' unlawful conduct without any alternative remedies; yet that is the regrettable effect of the ruling today that many state common law damages claims are preempted. The Court in the past has hesitated to find preemption where federal law provides no comparable remedy. Indeed, in Silkwood, the Court took note of "Congress' failure to provide any federal remedy" for injured persons, and stated that it was "difficult to believe that Congress would, without comment, remove all means of judicial recourse for those injured by illegal conduct."

Thus, not only does the plain language of the 1969 Act fail clearly to require preemption of petitioner's state common law damages claims, but there is no suggestion in the legislative history that Congress intended to expand the scope of the preemption provision in the drastic manner that the plurality attributes to it. Our obligation to infer preemption only where Congress' intent is clear and manifest mandates the conclusion that state common law damages actions are not preempted by the 1969 Act....

By finding federal preemption of certain state common law damages claims, the decision today eliminates a critical component of the States' traditional ability to protect the health and safety of their citizens....
 

JUSTICE SCALIA, with whom JUSTICE THOMAS joins, concurring in the judgment in part and dissenting in part.

Today's decision announces what, on its face, is an extraordinary and unprecedented principle of federal statutory construction: that express preemption provisions must be construed narrowly, "in light of the presumption against the preemption of state police power regulations."  The life span of this new rule may have been blessedly brief, inasmuch as the opinion that gives it birth in Part I proceeds to ignore it in Part V by adjudging at least some of the common law tort claims at issue here preempted. In my view, there is no merit to this newly crafted doctrine of narrow construction. Under the Supremacy Clause, U.S. Const., Art. VI, cl. 2, our job is to interpret Congress's decrees of preemption neither narrowly nor broadly, but in accordance with their apparent meaning. If we did that job in the present case, we would find, under the 1965 Act, preemption of the petitioner's failure-to-warn claims; and, under the 1969 Act, we would find preemption of the petitioner's claims complete.....

The test for preemption in this setting should be one of practical compulsion, i.e., whether the law practically compels the manufacturers to engage in behavior that Congress has barred the States from prescribing directly....

Like JUSTICE BLACKMUN, "I can only speculate as to the difficulty lower courts will encounter in attempting to implement [today's] decision." Must express preemption provisions really be given their narrowest reasonable construction, or need they not? Are courts to ignore all doctrines of implied preemption whenever the statute at issue contains an express preemption provision, as the Court says today, or are they to continue to apply them, as we have in the past? For pre-emption purposes,  does "state law" include legal duties imposed on voluntary acts, or does it not? These and other questions raised by today's decision will fill the lawbooks for years to come. A disposition that raises more questions than it answers does not serve the country well.