Upon respondent's federal conviction for possession of a firearm by a convicted felon, 18 U. S. C. sec.922(g)(1), he had three prior Washington state convictions for delivery of a controlled substance. At the time of those convictions, Washington law specified a maximum 5-year prison term for the first such offense. A recidivist provision, however, set a 10-year ceiling for a second or subsequent offense, and the state court had sentenced respondent to concurrent 48-month sentences on each count. The Government contended in the federal felon-in-possession case that respondent should be sentenced under the Armed Career Criminal Act (ACCA), sec.924(e), which sets a 15-year minimum sentence "[i]n the case of a person who violates [sec.922(g)] and has three previous convictions ... for a ... serious drug offense," sec.924(e)(1). Because a state drug-trafficking conviction qualifies as "a serious drug offense" if "a maximum term of imprisonment of ten years or more is prescribed by law" for the "offense," sec.924(e)(2)(A)(ii), and the maximum term on at least two of respondent's Washington crimes was 10 years under the state recidivist provision, the Government argued that these convictions had to be counted under ACCA. The District Court disagreed, holding that the "maximum term of imprisonment" for sec.924(e)(2)(A)(ii) purposes is determined without reference to recidivist enhancements. The Ninth Circuit affirmed.

Held: The "maximum term of imprisonment ... prescribed by law" for the state drug convictions at issue was the 10-year maximum set by the applicable state recidivist provision. Pp. 3-14.

(a) This reading is compelled by a straightforward application of sec.924(e)(2)(A)(ii)'s three key terms: "offense," "law," and "maximum term." The "offense" was the crime charged in each of respondent's drug-delivery cases. And because the relevant "law" is the state statutes prescribing 5- and 10-year prison terms, the "maximum term" prescribed for at least two of respondent's state drug offenses was 10 years. The Ninth Circuit's holding that the maximum term was 5 years contorts ACCA's plain terms. Although the state court sentenced respondent to 48 months, there is no dispute that state law permitted a sentence of up to 10 years. The Circuit's interpretation is also inconsistent with how the concept "maximum term of imprisonment" is customarily understood by participants in the criminal justice process. Pp. 3-5.

(b) Respondent's textual argument--that because "offense" generally describes a crime's elements, while prior convictions required for recidivist enhancements are not typically elements, such convictions are not part of the ACCA "offense," and the "maximum term" for the convictions at issue was the 5-year ceiling for simply committing the drug offense elements--is not faithful to the statutory text, which refers to the maximum 10-year term prescribed by Washington law for each of respondent's two relevant offenses. Respondent's "manifest purpose" argument--that because ACCA uses the maximum state-law penalty as shorthand for conduct sufficiently serious to trigger the mandatory penalty, while an offense's seriousness is typically gauged by the nature of the defendant's conduct, the offense's elements, and the crime's impact, a defendant's recidivist status has no connection to whether his offense was serious--rests on the erroneous proposition that a prior record has no bearing on an offense's seriousness. Respondent's understanding of recidivism statutes has been has squarely rejected. See, e.g., Nichols v. United States, 511 U. S. 738 . Pp. 5-7.

(c) Respondent's argument that the Court's ACCA interpretation produces a perverse bootstrapping whereby a defendant is punished under federal law for being treated as a recidivist under state law is rejected. The Court's reading is bolstered by the fact that ACCA is itself a recidivist statute, so that Congress must have understood that the "maximum penalty prescribed by [state] law" could be increased by state recidivism provisions. Contrary to respondent's suggestion, United States v. LaBonte, 520 U. S. 751 --in which the Court held that the phrase "maximum term authorized" in 28 U. S. C. sec.994(h) "refers to all applicable statutes," including recidivist enhancements--supports the Court's ACCA interpretation. Respondent's reliance on Taylor v. United States, 495 U. S. 575 , is also misplaced: There is no connection between the issue there (the meaning of "burglary" in sec.924(e)(2)(B)(ii)) and the meaning of "maximum term of imprisonment ... prescribed by law" in sec.924(e)(2)(A)(ii). Respondent argues unpersuasively that, under today's interpretation, offenses that are not really serious will be included as "serious drug offense[s]" because of recidivist enhancements. Since Congress presumably thought that state lawmakers must consider a crime "serious" when they provide a 10-year sentence for it, this Court's holding poses no risk that a drug-trafficking offense will be treated as "serious" without satisfying the standard Congress prescribed. Pp. 7-9.

(d) Also rejected is respondent's argument that the Court's holding will often require federal courts to engage in difficult inquiries regarding novel state-law questions and complex factual determinations about long-past state-court proceedings. Respondent greatly exaggerates the difficulties because (1) receipt of a recidivist enhancement will necessarily be evident from the sentence's length in some cases; (2) the conviction judgment will sometimes list the maximum possible sentence even where the sentence actually imposed did not exceed the top sentence allowed without recidivist enhancement; (3) some jurisdictions require the prosecution to submit a publicly available charging document to obtain a recidivist enhancement; (4) a plea colloquy will often include a statement by the trial judge regarding the maximum penalty; and (5) where the records do not show that the defendant faced a recidivist enhancement, the Government may well be precluded from establishing that a conviction was for a qualifying offense. Merely because future cases might present difficulties cannot justify disregarding ACCA's clear meaning. Pp. 10-11.

(e) Also unavailing is respondent's argument that if recidivist enhancements can increase the "maximum term" under ACCA, then mandatory guidelines systems capping sentences can decrease the "maximum term," whereas Congress cannot have wanted to make the "maximum term" dependent on the complexities of state sentencing guidelines. The phrase "maximum term of imprisonment ... prescribed by law" for the "offense" could not have been meant to apply to the top sentence in a guidelines range because (1) such a sentence is generally not really the maximum because guidelines systems typically allow a sentencing judge to impose a sentence that exceeds the top of the guidelines range under appropriate circumstances; and (2) in all of the many statutes predating ACCA and the federal Sentencing Reform Act of 1984 that used the concept of the "maximum" term prescribed by law, the concept necessarily referred to the maximum term prescribed by the relevant criminal statute, not the top of a sentencing guideline range. United States v. R. L. C., 503 U. S. 291 , n. 1, 299, distinguished. Pp. 11-14.

464 F. 3d 1072, reversed and remanded.

Alito, J., delivered the opinion of the Court, in which Roberts, C. J., and Scalia, Kennedy, Thomas, and Breyer, JJ., joined. Souter, J., filed a dissenting opinion, in which Stevens and Ginsburg, JJ., joined.

Kentucky exempts from state income taxes interest on bonds issued by it or its political subdivisions but not on bonds issued by other States and their subdivisions. After paying state income tax on out-of-state municipal bonds, respondents sued petitioners (hereinafter Kentucky) for a refund, claiming that Kentucky's differential tax impermissibly discriminated against interstate commerce. The trial court ruled for Kentucky, relying in part on a "market-participation" exception to the dormant Commerce Clause limit on state regulation. The State Court of Appeals reversed, finding that Kentucky's scheme ran afoul of the Commerce Clause.

Held: The judgment is reversed, and the case is remanded.

197 S. W. 3d 557, reversed and remanded.

Justice Souter delivered the opinion of the Court, except as to Part III-B, concluding that Kentucky's differential tax scheme does not offend the Commerce Clause. Pp. 7-13, 20-28.

(a) Modern dormant Commerce Clause law is driven by concern about "economic protectionism--that is, regulatory measures designed to benefit in-state economic interests by burdening out-of-state competitors," New Energy Co. of Ind. v. Limbach, 486 U. S. 269 --but that concern is limited by federalism favoring a degree of local autonomy. Under the resulting analysis, a discriminatory law is "virtually per se invalid." Oregon Waste Systems, Inc. v. Department of Environmental Quality of Ore., 511 U. S. 93 . An exception covers States that go beyond regulation and themselves "participat[e] in the market" to "exercis[e] the right to favor [their] own citizens over others," Hughes v. Alexandria Scrap Corp., 426 U. S. 794 , reflecting a "basic distinction ... between States as market participants and States as market regulators," Reeves, Inc. v. Stake, 447 U. S. 429 . Last Term, in a case decided independently of the market participant exception, this Court upheld an ordinance requiring trash haulers to deliver solid waste to a public authority's processing plant, finding that it addressed what was " 'both typically and traditionally a local government function,' " and did "not discriminate against interstate commerce for purposes of the dormant Commerce Clause," United Haulers Assn., Inc. v. Oneida-Herkimer Solid Waste Management Authority, 550 U. S. ___, ___. Pp. 7-10.

(b) United Haulers provides a firm basis for reversal here. The logic that a government function is not susceptible to standard dormant Commerce Clause scrutiny because it is likely motivated by legitimate objectives distinct from simple economic protectionism applies with even greater force to laws favoring a State's municipal bonds, since issuing debt securities to pay for public projects is a quintessentially public function, with a venerable history. Bond proceeds are a way to shoulder the cardinal civic responsibilities listed in United Haulers: protecting citizens' health, safety, and welfare. And United Haulers' apprehension about "unprecedented ... interference" with a traditional government function is warranted here, where respondents would have this Court invalidate a century-old taxing practice presently employed by 41 States and supported by all. In fact, emphasizing an enterprise's public character is just one step in addressing the fundamental element of dormant Commerce Clause jurisprudence that "any notion of discrimination assumes a comparison of substantially similar entities," id., at ___. Viewed through the lens of Bonaparte v. Tax Court, 104 U. S. 592 , there is no forbidden discrimination because Kentucky, as a public entity, does not have to treat itself as being "substantially similar" to other bond issuers in the market. Pp. 11-13.

(c) A look at the specific markets in which the exemption's effects are felt confirms that no traditionally forbidden discrimination is underway and points to the tax policy's distinctive character. In both the interstate market as most broadly conceived--issuers and holders of all fixed-income securities--and the more specialized market--commerce solely in federally tax-exemptmunicipal bonds, often conducted through interstate municipal bond funds--nearly every taxing State believes its public interests are served by the same tax-and-exemption feature which is supported in this Court by every State. These facts suggest that no State perceives any local advantage or disadvantage beyond the permissible ones open to a government and to those who deal with that government when it enters the market. An equally significant perception emerges from examining the market for municipal bonds within the issuing State, a large proportion of which market is managed by one or more single-state funds. An important feature of such markets is that intrastate funds absorb securities issued by smaller or lesser known municipalities that interstate markets tend to ignore. Many single-state funds would likely disappear if the current differential tax schemes were upset, and there is no suggestion that the interstate markets would welcome the weaker municipal issues that would lose their local market homes after a Davis victory. Financing for long-term municipal improvements would thus change radically if the differential tax feature disappeared. The fact that the differential tax scheme is critical to the operation of an identifiable segment of the current municipal financial market demonstrates that the States' unanimous desire to preserve the scheme is a far cry from the private protectionism that has driven the dormant Commerce Clause's development. Pp. 20-23.

(e) The Court generally applies the rule in Pike v. Bruce Church, Inc., 397 U. S. 137 , that even nondiscriminatory burdens on commerce may be struck down on a showing that they clearly outweigh the benefits of a state or local practice. But the current record and scholarly material show that the Judicial Branch is not institutionally suited to draw reliable conclusions of the kind that would be necessary for the Davises to satisfy a Pike burden in this particular case. Pp. 23-27.

Souter, J., announced the judgment of the Court and delivered the opinion of the Court, except as to Part III-B. Stevens and Breyer, JJ., joined that opinion in full; Roberts, C. J., and Ginsburg, J., joined all but Part III-B; and Scalia, J., joined all but Parts III-B and IV. Stevens, J., filed a concurring opinion. Roberts, C. J., and Scalia, J., filed opinions concurring in part. Thomas, J., filed an opinion concurring in the judgment. Kennedy, J., filed a dissenting opinion, in which Alito, J., joined. Alito, J., filed a dissenting opinion.

After this Court found facially overbroada federal statutory provision criminalizing the possession and distribution of material pandered as child pornography, regardless of whether it actually was that, Ashcroft v. Free Speech Coalition, 535 U. S. 234 , Congress passed the pandering and solicitation provision at issue, 18 U. S. C. sec.2252A(a)(3)(B). Respondent Williams pleaded guilty to this offense and others, but reserved the right to challenge his pandering conviction's constitutionality. The District Court rejected his challenge, but the Eleventh Circuit reversed, finding the statute both overbroad under the First Amendment and impermissibly vague under the Due Process Clause.

Held:

1. Section 2252A(a)(3)(B) is not overbroad under the First Amendment. Pp. 6-18.

(a) A statute is facially invalid if it prohibits a substantial amount of protected speech. Section 2252A(a)(3)(B) generally prohibits offers to provide and requests to obtain child pornography. It targets not the underlying material, but the collateral speech introducing such material into the child-pornography distribution network. Its definition of material or purported material that may not be pandered or solicited precisely tracks the material held constitutionally proscribable in New York v. Ferber, 458 U. S. 747 , and Miller v. California, 413 U. S. 15 : obscene material depicting (actual or virtual) children engaged in sexually explicit conduct, and any other material depicting actual children engaged in sexually explicit conduct. The statute's important features include: (1) a scienter requirement; (2) operative verbs that are reasonably read to penalize speech that accompanies or seeks to induce a child pornography transfer from one person to another; (3) a phrase--"in a manner that reflects the belief," ibid.--that has both the subjective component that the defendant must actually have held the "belief" that the material or purported material was child pornography, and the objective component that the statement or action must manifest that belief; (4) a phrase--"in a manner ... that is intended to cause another to believe," ibid --that has only the subjective element that the defendant must "intend" that the listener believe the material to be child pornography; and (5) a "sexually explicit conduct" definition that is very similar to that in the New York statute upheld in Ferber. Pp. 6-11.

(b) As thus construed, the statute does not criminalize a substantial amount of protected expressive activity. Offers to engage in illegal transactions are categorically excluded from First Amendment protection. E.g., Pittsburgh Press Co. v. Pittsburgh Comm'n on Human Relations, 413 U. S. 376 . The Eleventh Circuit mistakenly believed that this exclusion extended only to commercial offers to provide or receive contraband. The exclusion's rationale, however, is based not on the less privileged status of commercial speech, but on the principle that offers to give or receive what it is unlawful to possess have no social value and thus enjoy no First Amendment protection. The constitutional defect in Free Speech Coalition's pandering provision was that it went beyond pandering to prohibit possessing material that could not otherwise be proscribed. The Eleventh Circuit's erroneous conclusion led it to apply strict scrutiny to sec.2252A(a)(3)(B), lodging three fatal objections that lack merit. Pp. 11-18.

2. Section 2252A(a)(3)(B) is not impermissibly vague under the Due Process Clause. A conviction fails to comport with due process if the statute under which it is obtained fails to provide a person of ordinary intelligence fair notice of what is prohibited, or is so standardless that it authorizes or encourages seriously discriminatory enforcement. Hill v. Colorado, 530 U. S. 703 . In the First Amendment context plaintiffs may argue that a statute is overbroad because it is unclear whether it regulates a substantial amount of protected speech. Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U. S. 489 , and nn. 6 and 7. The Eleventh Circuit mistakenly believed that "in a manner that reflects the belief" and "in a manner ... that is intended to cause another to believe" were vague and standardless phrases that left the public with no objective measure of conformance. What renders a statute vague, however, is not the possibility that it will sometimes be difficult to determine whether the incriminating fact it establishes has been proved; but rather the indeterminacy of what that fact is. See, e.g., Coates v. Cincinnati, 402 U. S. 611 . There is no such indeterminacy here. The statute's requirements are clear questions of fact. It may be difficult in some cases to determine whether the requirements have been met, but courts and juries every day pass upon the reasonable import of a defendant's statements and upon "knowledge, belief and intent." American Communications Assn. v. Douds, 339 U. S. 382 . Pp. 18-21.

444 F. 3d 1286, reversed.

Scalia, J., delivered the opinion of the Court, in which Roberts, C. J., and Stevens, Kennedy, Thomas, Breyer, and Alito, JJ., joined. Stevens, J., filed a concurring opinion, in which Breyer, J., joined. Souter, J., filed a dissenting opinion, in which Ginsburg, J., joined.

After respondent gave false information on his customs form while attempting to enter the United States, a search of his car revealed explosives that he intended to detonate in this country. He was convicted of, inter alia, (1) feloniously making a false statement to a customs official in violation of 18 U. S. C. sec.1001, and (2) "carr[ying] an explosive during the commission of" that felony in violation of sec.844(h)(2). The Ninth Circuit set aside the latter conviction because it read "during" in sec.844(h)(2) to include a requirement that the explosive be carried "in relation to" the underlying felony.

Held: Since respondent was carrying explosives when he violated sec.1001, he was carrying them "during" the commission of that felony. The most natural reading of sec.844(h)(2) provides a sufficient basis for reversal. It is undisputed that the items in respondent's car were "explosives," and that he was "carr[ying]" those explosives when he knowingly made false statements to a customs official in violation of sec.1001. Dictionary definitions need not be consulted to arrive at the conclusion that he engaged in sec.844(h)(2)'s precise conduct. "[D]uring" denotes a temporal link. Because his carrying of explosives was contemporaneous with his sec.1001 violation, he carried them "during" that violation. The statute's history further supports the conclusion that Congress did not intend a relational requirement in sec.844(h) as presently written. Pp. 2-6

474 F. 3d 597, reversed.

Stevens, J., delivered the opinion of the Court, in which Roberts, C. J., and Kennedy, Souter, Ginsburg, and Alito, JJ., joined, and in which Scalia and Thomas, JJ., joined as to Part I. Thomas, J., filed an opinion concurring in part and concurring in the judgment, in which Scalia, J., joined. Breyer, J., filed a dissenting opinion.