Circuit Judge, concurring in the judgment:
We are asked in this case, as in so many others, to dance the Chevron two-step, under which
the court must first exhaust the traditional tools of statutory construction to determine whether Congress has spoken to the precise question at issue.... If the court can determine congressional intent, then that interpretation must be given effect.... If, on the other hand, the statute is silent or ambiguous with respect to the specific issue, then the court will defer to a permissible agency construction of the statute.
NRDC v. Browner, 57 F.3d 1122, 1125 (D.C.Cir.1995) (internal quotations omitted); see Chevron, U.S.A., Inc. v. NRDC, 467 U.S. 837, 842-43, 104 S.Ct. 2778, 2781, 81 L.Ed.2d 694 (1984) (“If the intent of Congress is clear, that is the end of the matter; for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress.”). Unlike the majority, I would stop the music at Chewon step one. In my view, a proper employment of “the traditional tools of statutory construction” yields a plain and affirmative congressional response “to the precise question at issue” — i.e., whether the Federal Election Campaign Act (FECA or Act) prohibits the Federal Election Commission (FEC or Commission) from disclosing thousands of pages of politically sensitive documents it obtained while investigating the AFL-CIO and the DNC (collectively, the appellees), now that the investigation has been completed.
My inquiry into the Congress’s intent proceeds, as it must, from “the fundamental canon that statutory interpretation begins with the language of the statute itself.” Butler v. West, 164 F.3d 634, 639 (D.C.Cir.1999) (quotation omitted); see Henry J. Friendly, Benchmarks 202 (1967) (“(1) Read the statute; (2) read the statute; (3) read the statute!” (quoting Justice Frankfurter’s “threefold imperative to law students”)). The Act’s confidentiality provision states, in full, that
[a]ny notification or investigation made under this section shall not be made public by the Commission or by any person without the written consent of the person receiving such notification or the person with respect to whom such investigation is made.
2 U.S.C. § 437g(a)(12)(A). Stretching the text in hopes of reaching the deference it enjoys under Chevron step two, the Commission contends that section 437g(a)(12)(A) “does not specifically address closed cases, and its silence about whether and when the confidentiality requirement expires leaves Congress’s intent on that question ambiguous.” Br. of Appellant at 14; see id. at 16-17 (citing United States v. Kanchanalak, 192 F.3d 1037, 1049 (D.C.Cir.1999) (FEC’s interpretation of FECA deserves “considerable deference” where statute ambiguous)). I disagree. While the provision does not state in so many words that “no completed investigation shall be made public,” that does not mean it is silent on the matter; whatever the word “investigation” means, section 437g(a)(12)(A) plainly covers “[a]ny ... investigation,” ongoing or completed. 2 U.S.C. § 437g(a)(12)(A) (emphasis added). Indeed, even though the provision does not explicitly state that “the FEC may not file information con*60cerning an ongoing investigation on the public record when it seeks to enforce a subpoena,” we recently held that it “unambiguously,” “directly” and “unequivocally” prohibits precisely that. See In re Sealed Case, 237 F.3d 657, 667 (D.C.Cir.2001). Taken to its logical conclusion, the FEC’s argument would render every prohibition in the United States Code susceptible of ambiguity. “Thou shall not kill” is a mandate neither silent nor ambiguous about whether murder is permissible if committed after 5.00 p.m. — or, for that matter, if committed in the billiard room with the candlestick — but the FEC’s reasoning would lead one to conclude otherwise.
Moreover, the fact that the provision does not specify “when the confidentiality requirement expires” suggests to me that it never expires. Resisting this logic, the Commission contends that the “disclosures ... required by other provisions of section 437g(a) when the administrative proceeding concludes ... make section 437g(a)(12)(A) inapplicable to closed cases.” Br. of Appellant at 20-21. In doing so, the FEC again neglects the plain language of the statute; section 437g(a)(12)(A)’s prohibition against disclosure of an “investigation” or a “notification” admits of no textual exceptions. See Sealed Case, 237 F.3d at 667. Time, section 437g(a) elsewhere states that “the Commission shall make public any conciliation agreement signed by both the Commission and the respondent.” 2 U.S.C. § 437g(a)(4)(B)(ii) (emphasis added). True, it also provides that “[i]f the Commission makes a determination that a person has not violated this Act ... [it] shall make public such determination.” Id. (emphasis added). But section 437g(a) nowhere requires or permits the FEC to disclose an “investigation” or a “notification.” Nor should we be willing, in the face of well-settled principles of statutory construction, to equate the distinct terms- — •“investigation”/“notification” on the one hand and “conciliation agreement”/“ determination” on the other — such that disclosure of an “investigation” is permitted under the circumstances enumerated in section 437g(a)(4)(B)(ii). See Barnhart v. Sigmon Coal Co., 534 U.S. 438, 452, 122 S.Ct. 941, 951, 151 L.Ed.2d 908 (2002) (“[W]hen Congress includes particular language in one section of a statute but omits it in another section ... , it is,generally presumed that Congress acts intentionally and purposely in the disparate inclusion or exclusion.” (quotations omitted)); Russello v. United States, 464 U.S. 16, 23, 104 S.Ct. 296, 300, 78 L.Ed.2d 17 (1983) (“We refrain from concluding ... that the differing language in the two subsections has the same meaning in each.”); see also 2A Norman J. Singer, Sutherland’s Statutes and Statutory Construction § 46.06, at 194 (6th ed.2000) (“[W]hen the legislature uses certain language in one part of the statute and different language in another, the court assumes different meanings were intended.”). If the Congress had meant to exclude the majority1 of “investigation^]” from the otherwise comprehensive shelter of section 437g(a)(12)(A), it would have done so more obviously than the FEC suggests — either by including “investigation” in section 437g(a)(4)(B)(ii), as it did in section 437g(a)(12)(A), or by removing completed “investigation[s]” from the latter’s coverage explicitly. See Russello, 464 U.S. at 23, 104 S.Ct. at 300 (“We would not presume to ascribe this difference [in the subsections’ language] to a simple mistake in draftsmanship.”); cf. Cal. Med. Ass’n v. FEC, 453 U.S. 182, 191, 101 S.Ct. 2712, *612719, 69 L.Ed.2d 567 (1981) (“If Congress had intended to remove a whole category of constitutional challenges from the purview of § 437h, thereby significantly limiting the usefulness of that provision, it surely would have made such a limitation explicit.”). In my view, therefore, section 437g(a)(12)(A) plainly prohibits publication of any “investigation,” whether it is ongoing or completed.
In a belated nod to ordinary meaning, and in the absence of a statutory definition, the Commission claims that “investigation” refers to “a process for discovering facts, not a file of documents.”2 Br. of Appellant at 22 (citing Black’s Law Dictionary 825 (6th ed.1990); 8 Oxford English Dictionary 47 (2d ed.1989); Random House Dictionary of the English Language, Unabridged 1004 (2d ed.1983)) (emphasis in original). It argues that section 437g(a)(12)(A) prohibits disclosure of the fact that an investigative process is occurring or has occurred but does not cover .the documents generated during the process. Once again, I disagree.
Although we observed in Sealed Case that the main purpose of section 437g(a)(12)(A) is “to protect [an] ... accused who is exonerated from disclosure of the fact that he has been under investigation,” Sealed Case, 237 F.3d at 667 (quoting United States v. Procter & Gamble Co., 356 U.S. 677, 682 n. 6, 78 S.Ct. 983, 986 n. 6, 2 L.Ed.2d 1077 (1958)) (emphasis added), we suggested as well that the “investigation[s]” to be kept confidential include all documentary materials gathered during the “process” to which the FEC refers:
When the FEC issues a subpoena as part of an investigation, § 437g mandates those subpoenas, like other components of the investigation, “shall not be made public.”.... Even if we assume that the FEC’s argument is correct (which it is not) and the Commission could disclose the subpoenas themselves (which it cannot), the Commission would still lack the authority to divulge information pertaining to the underlying investigation....
Sealed Case, 237 F.3d at 667-68 (emphases altered); see id. at 668 (“We cannot fathom why the FEC’s issuance of a subpoena in furtherance of an ongoing investigation would not be considered part of that ‘investigation’ within the meaning of § 437g.”). Indeed, we stated without qualification that the FEC cannot “under any circumstances ... introduce evidence concerning an ongoing investigation on the public record” without the written consent of the subject of the investigation.3 Id. at 667, 669 (emphasis added).
*62Even if Sealed Case does not give an all-eneompassing interpretation to “investigation” — and I acknowledge that it (properly) does not — the thoroughgoing First Amendment analysis in today’s majority opinion, in my view, removes any doubt that the term covers the documents at issue here. The majority quite justifiably echoes the concern of amicus cunae, the James Madison Center for Free Speech, that the Commission’s automatic disclosure policy “encourages political opponents to file charges against their competitors to serve the dual purpose of ‘chilling’ the expressive efforts of their competitor and learning their political strategy so that it can be exploited to the complainant’s advantage.” Maj. op. at 178-179 (quoting Br. of Amicus Curiae James Madison Center at 20). I agree that the Commission has failed to show that the speech-chilling disclosure regulation set forth in 11 C.F.R. § 5.4 bears a “relevant correlation or substantial relation” to a “substantial governmental interest[ ].” Buckley v. Valeo, 424 U.S. 1, 64, 68, 96 S.Ct. 612, 656, 658, 46 L.Ed.2d 659 (1976) (per curiam) (quotations omitted); see maj. op. at 177-178. But I believe the majority commits an error — if only a minor one — in holding that the “serious constitutional difficulties” raised by the regulation preclude the court from deferring to the Commission’s interpretation at Chevron step two. Chamber of Commerce v. FEC, 69 F.3d 600, 605 (D.C.Cir.1995); see maj. op. at 175-176. In my view, those very same difficulties vindicate, at Chevron step one, the appellees’ contention that the Act “unambiguously” prohibits the FEC from publicizing the documents at issue. Chevron, 467 U.S. at 843, 104 S.Ct. at 2781-82; see Br. of Appellees at 12-27; see also AFL-CIO v. FEC, 177 F.Supp.2d 48, 59 (D.D.C.2001) (“[T]he plain meaning of § 437g(a)(12)(A) prohibits the FEC from disclosing the investigative file.”).
Among the “traditional tools of statutoiy construction” “the court must first exhaust” under Chevron and its progeny are the linguistic and substantive canons of interpretation, one of which — the canon of “constitutional avoidance” — is particularly useful in resolving the dispute before us. Invoking the canon in Edward J. DeBartolo Corp. v. Florida Gulf Coast Building & Construction Trades Council, 485 U.S. 568, 108 S.Ct. 1392, 99 L.Ed.2d 645 (1988), the United States Supreme Court held that “where an otherwise acceptable [agency] construction of a statute would raise serious constitutional problems, the Court will construe the statute to avoid such problems unless such construction is plainly contrary to the intent of Congress.” Id. at 575, 108 S.Ct. at 1397. Language like this might suggest that the canon operates at Chevron step two or even displaces Chevron altogether. But the Court in DeBartolo made clear that the avoidance canon
not only reflects the prudential concern that constitutional issues [should] not be needlessly confronted, but also recognizes that Congress, like this Court, is bound by and swears an oath to uphold the Constitution. The courts will therefore not lightly assume that Congress intended to infringe constitutionally protected liberties or usurp power constitutionally forbidden it.
DeBartolo, 485 U.S. at 575, 108 S.Ct. at 1397-98 (emphasis added); see Grenada County Supervisors v. Brown, 112 U.S. 261, 269, 5 S.Ct. 125, 129, 28 L.Ed. 704 (1884) (“It ought never to be assumed that the law-making department of the government intended to usurp or assume power prohibited to it.” (quotation omitted)). In other words, the canon assists us in determining the Congress’s intent and, accordingly, it operates at Chevron step one. Circuit precedent supports this proposi*63tion; we recently reaffirmed that “[i]f employment of an accepted canon of construction illustrates that Congress had a specific intent on the issue in question, then the case can be disposed of under the first prong of Chevron.” Halverson v. Slater, 129 F.3d 180, 184 (D.C.Cir.1997) (emphasis and quotations omitted); see Mich. Citizens for an Indep. Press v. Thornburgh, 868 F.2d 1285, 1292-93 (D.C.Cir.), aff'd by equally divided Court, 493 U.S. 38, 110 S.Ct. 398, 107 L.Ed.2d 277 (1989).
In sum, I do not believe the Congress intended section 437g(a)(12)(A) to apply so narrowly as to permit the Commission to publicize the documents at issue, in light of the “serious constitutional difficulties” attending such publication.
* * *
For the foregoing reasons, I would hold that section 437g(a)(12)(A) plainly prohibits the FEC from disclosing investigative records pertaining to a completed investigation if the investigated party does not consent to disclosure. While I disagree somewhat with the reasoning of my colleagues, I do agree that the district court’s December 19, 2001 judgment should be affirmed because the Commission’s interpretation of the Act is “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law,” 5 U.S.C. § 706(2)(A).
. There are far fewer open cases at any given time than there are closed ones — a disparity that will inevitably grow over time as ongoing investigations are completed.
. As the appellees point out, the FEC did not articulate this proposition “in its administrative dispositions of [the appellees’] objections to public release of the investigative file, where the Commission otherwise extensively analyzed FECA, its legislative history, the FEC's regulations and FOIA.’’ Br. of Appellees at 19 n.ll. “Rather,” they note, "this argument first surfaced in the FEC’s briefs on the cross-motions for summary judgment.” Id.
. Even if the Commission's reading of "investigation” were correct, section 437g(a)(12)(A) would nonetheless prohibit the FEC from disclosing several of the documents it planned to (and initially did) publicize in April 2001. The written correspondence among and between the appellees, their counsel and the Commission, for example, would inevitably reveal upon publication the fact that the appellees had been investigated. Because the correspondence is neither a “conciliation agreement signed by both the Commission and the [appellees],” 2 U.S.C. § 437g(a)(4)(B)(ii), nor a “determination that [the appellees have] not violated this Act,” id., the Act would plainly foreclose publication of the correspondence even under the Commission's “process” interpretation of "investigation.”