dissenting.
The parties agree that aflatoxins are added, unavoidable contaminants of food and as such are governed by the following provision of the Federal Food, Drug, and Cosmetic Act:
“[W]hen such substance . . . cannot be so avoided, the Secretary shall promulgate regulations limiting the quantity therein or thereon to such extent as he finds necessary for the protection of public health, and any quantity exceeding the limits so fixed shall also be deemed to be unsafe for purposes of the application of clause (2)(A) of section 342(a) of this title.” 21 U. S. C. § 346 (emphasis added).
To one versed in the English language, the meaning of this provision is readily apparent. The plain language of the section tells us when the Secretary’s duty to promulgate regulations arises — “when such substance . . . cannot be so avoided”; it tells us the purpose of the regulations — to estab*985lish a tolerance level that will enable manufacturers to know what they can lawfully produce and to enable the public to know what they can safely consume; and it tells us what standard he should employ in drafting them — “to such extent as he finds necessary for the protection of public health.” For purposes of deciding this case, the parties’ agreement that aflatoxins are substances that “cannot be so avoided” within the meaning of the section triggers the obligation to initiate rulemaking.
The Court’s contrary conclusion reflects an absence of judgment and of judging. Before exploring either infirmity, it is worthwhile to summarize the Court’s reason for reading the section to authorize, but not require, the promulgation of regulations. First, the Court declares that the qualifying language — “to such extent as he finds necessary for protection of the public health” — is a “dangling participle” that might or might not modify the words “shall promulgate regulations.” Ante, at 981. Second, as between the two readings of this “ambiguous statutory provision,” ibid., deference dictates that the Commissioner of the Food and Drug Administration (FDA) (to whom enforcement of the Act has been delegated) may take his pick.
The Court’s finding of ambiguity is simply untenable. The antecedent of the qualifying language is quite clearly the phrase “limiting the quantity therein or thereon,” which immediately precedes it, rather than the word “shall,” which appears eight words before it. Thus, the Commissioner is to “limi[t] the quantity [of an added, unavoidable poisonous or deleterious substance] therein or thereon to such extent as he finds necessary for the protection of public health.”1 By in*986stead reading the section to mean that “the Secretary shall promulgate regulations ... to such extent as he finds necessary,” the Court ignores the import of the words immediately following, which specify the effect of the “limits so fixed”— i. e., fixed by “limiting the quantity [of the poisonous substance] therein or thereon to such extent as he finds necessary for the protection of public health” — which can only mean that the qualification modifies the limits set by regulation rather than the duty to regulate. In addition, the Court’s construction, by skipping over the words “limiting the quantity therein or thereon,” renders them superfluous and of no operative force or effect. Indeed, the Court renders the very language it construes superfluous, because reading the provision to authorize (rather than mandate) the promulgation of regulations assigns it an office already filled by the general rulemaking authority conferred later in the Food, Drug, and Cosmetic Act. See 21 U. S. C. § 371(a).2 If Congress intended the Secretary to have unbridled authority to proceed with action levels, instead of with formal regulations, there was no need to enact this part of § 346 at all. This is plainly a case in which “the intent of Congress is clear [and] the court, as well as the agency, must give effect to the *987unambiguously expressed intent of Congress.” Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 842-843 (1984).3
*988The task of interpreting a statute requires more than merely inventing an ambiguity and invoking administrative deference. A statute is not “unclear unless we think there are decent arguments for each of two competing interpretations of it.” R. Dworkin, Law’s Empire 352 (1986). Thus, to say that the statute is susceptible of two meanings, as does the Court, is not to say that either is acceptable. Furthermore, to say that the Commissioner’s interpretation of the statute merits deference, as does the Court, is not to say that the singularly judicial role of marking the boundaries of agency choice is at an end. As Justice Frankfurter reminds us, “[t]he purpose of construction being the ascertainment of meaning, every consideration brought to bear for the solution of that problem must be devoted to that end alone.” Frankfurter, Some Reflections on the Reading of Statutes, 47 Colum. L. Rev. 527, 529 (1947). It is not “a ritual to be observed by unimaginative adherence to well-worn professional phrases.” Ibid. “Nor can canons of construction save us from the anguish of judgment.” Id., at 544. The Court, correctly self-conscious of the limits of the judicial role, employs a reasoning so formulaic that it trivializes the art of judging.
I respectfully dissent.
This interpretation is in accord with the Committee Report on the House bill, which became the Food, Drug, and Cosmetic Act of 1938. The Report states that “[t]he addition of poison to foods is prohibited except where such addition is necessary or cannot be avoided; and in such eases tolerances are provided limiting the amount of added poison to the extent necessary to safeguard the public health.” H. R. Rep. No. 2139, 75th *986Cong., 3d Sess., pt. 1, p. 2 (1938) (emphasis added). By using the present tense, the Report makes clear that the qualifying language is operative when regulations are promulgated — to limit the amount of poison “to the extent necessary to safeguard the public health.” The qualifying language thus defines the standard by which tolerances are to be determined and not the occasions on which regulations are to be promulgated.
The Court does not deny that the specific language which it construes — the clause providing that “the Secretary shall promulgate regulations” setting tolerance levels — is superfluous under its view of the Act. See ante, at 983-984. It instead emphasizes that a later sentence in § 346 which prescribes the legal effect of tolerance-setting regulations remains effective. But since tolerances may be promulgated pursuant to § 371(a) as well as § 346, the Court’s response merely underscores the fact that its construction of the “shall promulgate” clause to authorize rather than to require such rulemaking renders it redundant to the general rulemaking authority conferred by § 371(a).
Because Congress explicitly required the Commissioner to promulgate regulations for added, unavoidable contaminants, that should be “the end of the matter.” Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S., at 842. The Commissioner’s “longstanding” practice to the contrary does not help his legal position. For even if it were true that the Commissioner has from time to time announced an “action level” to advise the industry when he intended to institute enforcement proceedings concerning certain deleterious substances, the fact that the FDA had never actually addressed in any detail the statutory authorization under which it took such action means that its plea for deference should fail for the reasons carefully stated in SEC v. Sloan, 436 U. S. 103, 117-118 (1978):
“The Commission next argues that its interpretation of the statute — that the statute authorizes successive suspension orders — has been both consistent and longstanding, dating from 1944. It is thus entitled to great deference. See United States v. National Assn. of Securities Dealers, 422 U. S. 694, 710 (1975); Saxbe v. Bustos, 419 U. S. 65, 74 (1974).
“While this undoubtedly is true as a general principle of law, it is not an argument of sufficient force in this case to overcome the clear contrary indications of the statute itself. In the first place it is not apparent from the record that on any of the occasions when a series of consecutive summary suspension orders was issued the Commission actually addressed in any detail the statutory authorization under which it took that action.
“[S]ince this Court can only speculate as to the Commission’s reasons for reaching the conclusion that it did, the mere issuance of consecutive summary suspension orders, without a concomitant exegesis of the statutory authority for doing so, obviously lacks ‘power to persuade’ as to the existence of such authority. [Adamo Wrecking Co. v. United States, 434 U. S. 275, 287-288, n. 5 (1978)].”
As we emphasized in FMC v. Seatrain Lines, Inc., 411 U. S. 726, 745 (1973), “an agency may not bootstrap itself into an area in which it has no jurisdiction by repeatedly violating its statutory mandate.” Instead, “our clear duty in such a situation is to reject the administrative interpretation of the statute.” SEC v. Sloan, 436 U. S., at 119.
The Sloan case also provides an adequate answer to the argument that Congress has revisited the statute from time to time without condemning the FDA’s “action level” practice:
*988“We are extremely hesitant to presume general congressional awareness of the Commission’s construction based only upon a few isolated statements in the thousands of pages of legislative documents. That language in a Committee Report, without additional indication of more widespread congressional awareness, is simply not sufficient to invoke the presumption in a case such as this. For here its invocation would result in a construction of the statute which not only is at odds with the language of the section in question and the pattern of the statute taken as a whole, but also is extremely far reaching in terms of the virtually untrammeled and unreviewable power it would vest in a regulatory agency.” Id,., at 121.