(Slip Opinion) OCTOBER TERM, 2000 1 Syllabus NOTE: Where it is feasible, a syllabus (headnote) will be released, as is being done in connection with this case, at the time the opinion is issued. The syllabus constitutes no part of the opinion of the Court but has been prepared by the Reporter of Decisions for the convenience of the reader. See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. SUPREME COURT OF THE UNITED STATES Syllabus LOPEZ v. DAVIS, WARDEN, ET AL. CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE EIGHTH CIRCUIT No. 99­7504. Argued October 30, 2000- Decided January 10, 2001 Under 18 U. S. C. §3621(e)(2)(B), "[t]he period a [federal] prisoner con- victed of a nonviolent offense remains in custody after successfully completing a [substance abuse] treatment program may be reduced by the Bureau of Prisons" (BOP). The BOP therefore ranked ineligi- ble for early release all inmates incarcerated for "crime[s] of vio- lence." Initially, the BOP defined the term "crimes of violence" to in- clude, among other offenses, a drug trafficking conviction under 21 U. S. C. §841, if the offender received a two-level sentence enhance- ment under United States Sentencing Commission, Guidelines Man- ual (USSG) §2D1.1(b)(1), for possessing a dangerous weapon in con- nection with the drug offense. The Courts of Appeals thereafter divided over the validity of classifying drug offenses involving fire- arms possession as crimes of violence. The Circuit division prompted the BOP to issue the regulation now before the Court. That regula- tion denies early release to several categories of prisoners, including inmates whose current offense is a felony attended by "the carrying, possession, or use of a firearm." 28 CFR §550.58(a)(1)(vi)(B). The BOP rests this denial not on a definition of "crimes of violence," but on the BOP's asserted discretion to prescribe additional early release criteria. Petitioner Lopez was convicted of possession with intent to distrib- ute methamphetamine in violation of 21 U. S. C. §841. Finding that Lopez possessed a firearm in connection with his offense, the District Court enhanced his sentence by two levels pursuant to USSG §2D1.1(b)(1). While incarcerated, Lopez requested substance abuse treatment. The BOP found him qualified for its treatment program, but categorically ineligible, under 28 CFR §550.58(a)(1)(vi), for early release. Ordering the BOP to reconsider Lopez's eligibility for early 2 LOPEZ v. DAVIS Syllabus release, the District Court held that the BOP may not categorically count out, based upon sentencing factors or weapon possession, in- mates whose underlying conviction was for a nonviolent crime. The Eighth Circuit reversed. It reasoned that §3621(e)(2)(B)'s "may . . . reduc[e]" formulation allows the BOP discretion to devise a regime based on criteria that can be uniformly applied. To the extent Con- gress left a gap in §3621(e)(2)(B) for the BOP to fill, the Court of Ap- peals stated, deference is owed the BOP's interpretation under Chev- ron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 843­845, 866, so long as the interpretation is a permissible con- struction of the statute. The BOP's decision to deny early release to drug traffickers who carry firearms, the court concluded, represents a manifestly permissible statutory construction and an appropriate exer- cise of discretion. Held: The regulation at issue is a permissible exercise of the BOP's dis- cretion under §3621(e)(2)(B). Pp. 7­14. (a) Section 3621(e)(2)(B) gives the BOP discretion to grant or deny a sentence reduction, but leaves open the manner in which the dis- cretion is to be exercised. If an inmate meets the two statutory pre- requisites for sentence reduction- conviction of a nonviolence offense and successful completion of drug treatment- then §3621(e)(2)(B) in- structs that the BOP "may," not that it must, grant early release. The statute's use of the permissive "may" contrasts with Congress' use of a mandatory "shall" elsewhere in §3621 to impose discretion- less obligations, e.g., the obligation to provide drug treatment when funds are available, see §3621(e)(1). Sensibly read, §3621(e)(2)(B)'s sentence reduction discretion parallels the grant of discretion in §3621(e)(2)(A) to retain a prisoner who successfully completes drug treatment "under such [custodial] conditions as the [BOP] deems ap- propriate." The constraints Lopez urges- requiring the BOP to make individualized determinations based only on postconviction conduct- are nowhere to be found in §3621(e)(2)(B). Beyond instructing that the BOP has discretion to reduce the period of imprisonment for a nonviolent offender who successfully completes drug treatment, Con- gress has not identified any further circumstance in which the BOP either must grant the reduction, or is forbidden to do so. In this fa- miliar situation, where Congress has enacted a law that does not an- swer the precise question at issue, all this Court must decide is whether the BOP, the agency empowered to administer the early re- lease program, has filled the statutory gap in a way that is reason- able in light of the Legislature's revealed design. E.g., NationsBank of N. C., N. A. v. Variable Annuity Life Ins. Co., 513 U. S. 251, 257. Pp. 7­11. (b) The BOP may categorically exclude prisoners from early release Cite as: 531 U. S. ____ (2001) 3 Syllabus eligibility based on their preconviction conduct. The Court rejects Lopez's argument that the BOP may take into account only postcon- viction conduct. The BOP need not blind itself to preconviction con- duct that the agency reasonably views as jeopardizing life and limb. By denying eligibility to violent offenders, the statute manifests con- gressional concern for preconviction behavior- and for the very con- duct leading to conviction. The BOP may reasonably attend to these factors as well. The statute's restriction of early release eligibility to nonviolent offenders does not cut short the considerations that may guide the BOP in implementing §3621(e)(2)(B). See INS v. Yueh- Shaio Yang, 519 U. S. 26, 31. The Court also rejects Lopez's argu- ment that the BOP must not make categorical exclusions, but may rely only on case-by-case assessments. Even if a statutory scheme requires individualized determinations, which this scheme does not, the decisionmaker has the authority to rely on rulemaking to resolve certain issues of general applicability unless Congress clearly ex- presses an intent to withhold that authority. E.g., Heckler v. Camp- bell, 461 U. S. 458, 467. The approach pressed by Lopez- case-by-case decisionmaking in thousands of cases each year- could invite favor- itism, disunity, and inconsistency. Pp. 11­13. (c) The regulation excluding Lopez is permissible. The BOP rea- sonably concluded that an inmate's prior involvement with firearms, in connection with the commission of a felony, suggests his readiness to resort to life-endangering violence and therefore appropriately de- termines the early release decision. P. 13. 186 F. 3d 1092, affirmed. GINSBURG, J., delivered the opinion of the Court, in which O'CONNOR, SCALIA, SOUTER, THOMAS, and BREYER, JJ., joined. STEVENS, J., filed a dissenting opinion, in which REHNQUIST, C. J., and KENNEDY, J., joined. Cite as: 531 U. S. ____ (2001) 1 Opinion of the Court NOTICE: This opinion is subject to formal revision before publication in the preliminary print of the United States Reports. Readers are requested to notify the Reporter of Decisions, Supreme Court of the United States, Wash- ington, D. C. 20543, of any typographical or other formal errors, in order that corrections may be made before the preliminary print goes to press. SUPREME COURT OF THE UNITED STATES _________________ No. 99­7504 _________________ CHRISTOPHER A. LOPEZ, PETITIONER v. RANDY J. DAVIS, WARDEN, ET AL. ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE EIGHTH CIRCUIT [January 10, 2001] JUSTICE GINSBURG delivered the opinion of the Court. Congress has provided, in 18 U. S. C. §3621(e)(2)(B), that the Bureau of Prisons (Bureau or BOP) may reduce by up to one year the prison term of an inmate convicted of a nonviolent felony, if the prisoner successfully completes a substance abuse program. The Bureau's implementing regulation categorically denies early release to prisoners whose current offense is a felony attended by "the carry- ing, possession, or use of a firearm." 28 CFR §550.58(a)(1)(vi)(B) (2000). The validity of the Bureau's regulation is the question presented in this case. We hold, in accord with the Court of Appeals for the Eighth Circuit, that the regulation is a permissible exercise of the Bu- reau's discretion under 18 U. S. C. §3621(e)(2)(B). IA Title 18 U. S. C. §3621 governs the imprisonment of persons convicted of federal crimes. In 1990, Congress amended the statute to provide that "[t]he Bureau shall . . . make available appropriate substance abuse treatment for each prisoner the Bureau determines has a treatable 2 LOPEZ v. DAVIS Opinion of the Court condition of substance addiction or abuse." Pub. L. 101­ 647, §2903, 104 Stat. 4913. Four years later, Congress again amended §3621, this time to provide incentives for prisoner participation in BOP drug treatment programs. The incentive provision at issue reads: "The period a prisoner convicted of a nonviolent offense remains in custody after successfully completing a treatment program may be reduced by the Bureau of Prisons, but such reduction may not be more than one year from the term the prisoner must otherwise serve." Pub. L. 103­ 322, §32001, 108 Stat. 1897 (codified at 18 U. S. C. §3621(e)(2)(B)). In 1995, the Bureau published a rule to implement the early release incentive. 60 Fed. Reg. 27692­27695; 28 CFR §550.58. Because the statute explicitly confined the incentive to prisoners convicted of "nonviolent offense[s]," 18 U. S. C. §3621(e)(2)(B), the BOP ranked ineligible for early release all inmates currently incarcerated for "crime[s] of violence," 60 Fed. Reg. 27692. As explained in the Bureau's program statement, the BOP defined "crimes of violence" to include a drug trafficking conviction under 21 U. S. C. §841, if the offender received a two-level sen- tence enhancement under United States Sentencing Commission, Guidelines Manual (USSG) §2D1.1(b)(1), for possessing a dangerous weapon during commission of the drug offense. Bureau of Prisons Program Statement No. 5162.02, §9 (July 24, 1995), reprinted in App. to Brief for Petitioner 17­18.1 "[E]xercising [its] discretion in - - - - - - 1 Title 21 U. S. C. §§841(a)(1) and (2) make it unlawful "to manufac- ture, distribute, or dispense, or possess with intent to manufacture, distribute, or dispense, a controlled substance," or "to create, distribute, or dispense, or possess with intent to distribute or dispense, a counter- feit substance." Section 2D1.1(b)(1) of the Sentencing Guidelines provides for a two-level sentence enhancement if a dangerous weapon was possessed in connection with the commission of a drug offense. See USSG §2D1.1(b)(1) and comment, n. 3 (Nov. 2000). Cite as: 531 U. S. ____ (2001) 3 Opinion of the Court reducing a sentence," the Bureau also excluded from early release eligibility inmates who had a prior conviction "for homicide, forcible rape, robbery, or aggravated assault." 60 Fed. Reg. 27692 (codified at 28 CFR §550.58 (1995)). The Courts of Appeals divided over the validity of the Bureau's definition of crimes of violence to include drug offenses that involved possession of a firearm. A majority of Circuits, including the Eighth, held that §3621(e)(2)(B) required the Bureau to look only to the offense of convic- tion (drug trafficking), and not to sentencing factors (fire- arm possession), in determining whether an offender was convicted of a "nonviolent offense," and was therefore eligible under the statute for the early release incentive. Martin v. Gerlinski, 133 F. 3d 1076, 1079 (CA8 1998); see also Fristoe v. Thompson, 144 F. 3d 627, 631 (CA10 1998); Byrd v. Hasty, 142 F. 3d 1395, 1398 (CA11 1998); Roussos v. Menifee, 122 F. 3d 159, 164 (CA3 1997); Downey v. Crabtree, 100 F. 3d 662, 668 (CA9 1996). The Fourth and Fifth Circuits, however, upheld the Bureau's classification of drug offenses attended by firearm possession as violent crimes. Pelissero v. Thompson, 170 F. 3d 442, 447 (CA4 1999); Venegas v. Henman, 126 F. 3d 760, 763 (CA5 1997). This split among the Circuits prompted the Bureau in 1997 to publish the regulation now before the Court. See 62 Fed. Reg. 53690­53691. Like the 1995 rule, the cur- rent regulation excludes from early release eligibility offenders who possessed a firearm in connection with their offenses. In contrast to the earlier rule, however, the 1997 regulation does not order this exclusion by defining the statutory term "prisoner convicted of a nonviolent offense" or the cognate term "crimes of violence." Instead, the current regulation relies upon "the discretion allotted to the Director of the Bureau of Prisons in granting a sen- tence reduction to exclude [enumerated categories of ] inmates." Id., at 53690. The regulation, designed to achieve consistent administration of the incentive, now 4 LOPEZ v. DAVIS Opinion of the Court provides: "(a) Additional early release criteria. (1) As an exer- cise of the discretion vested in the Director of the Fed- eral Bureau of Prisons, the following categories of in- mates are not eligible for early release: . . . . . "(iv) Inmates who have a prior felony or misde- meanor conviction for homicide, forcible rape, robbery, or aggravated assault, or child sexual abuse offenses; . . . . . "(vi) Inmates whose current offense is a felony: . . . . . "(B) That involved the carrying, possession, or use of a firearm or other dangerous weapon . . . ." 28 CFR §550.58(a)(2000). In sum, the 1995 rule defined the statutory term "pris- oner convicted of a nonviolent offense" to exclude categori- cally an inmate who possessed a firearm in connection with his offense. The current regulation categorically excludes such an inmate, not because §3621(e)(2)(B) so mandates, but pursuant to the Bureau's asserted discre- tion to prescribe additional early release criteria. Drug traffickers who possess firearms when they engage in crimes are no longer characterized as "violent" offenders within the meaning of the statute. But they are brack- eted, for sentence reduction purposes, with persons cur- rently incarcerated for "nonviolent offense[s]" who in the past committed crimes qualifying as violent. The precon- viction conduct of both armed offenders and certain redi- civists, in the Bureau's view, "suggest[s] that they pose a particular risk to the public." Brief for Respondents 30. B In 1997, petitioner Christopher A. Lopez was convicted of possession with intent to distribute methamphetamine, Cite as: 531 U. S. ____ (2001) 5 Opinion of the Court in violation of 21 U. S. C. §841. Upon finding that Lopez possessed a firearm in connection with his offense, the District Court enhanced his sentence by two levels pursu- ant to USSG §2D1.1(b)(1). Lopez is currently scheduled to be released from prison in June 2002. While incarcerated, Lopez requested substance abuse treatment. The Bureau found him qualified for its resi- dential drug abuse program,2 but categorically ineligible, under 28 CFR §550.58(a)(1)(vi), for early release. App. 3­ 7. When notified that he would not be a candidate for early release, Lopez challenged the BOP's determination by filing a petition for a writ of habeas corpus, under 28 U. S. C. §2241, in the United States District Court for the District of South Dakota. The District Court granted the petition. In that court's view, the Bureau's 1997 regula- tion did not correct the infirmity the Eighth Circuit saw in the 1995 rule. See App. 17­18, and n. 4 (citing Martin, 133 F. 3d, at 1079). "[I]t is true," the Distric t Court recog- nized, "that the BOP may exercise a great deal of discre- tion in determining who among the eligible nonviolent offenders may be released." App. 17. But, the District Court held, the BOP may not categorically count out, "based upon sentencing factors or weapon possession," inmates whose underlying conviction was for a nonviolent crime. Id., at 18. Accordingly, the District Court ordered the BOP "to reconsider Lopez's eligibility for early re- lease." Id., at 19. The Eighth Circuit reversed. Bellis v. Davis, 186 F. 3d 1092 (1999). Section 3621(e)(2)(B), the Court of Appeals observed, "states only that the prison term of an inmate - - - - - - 2 To qualify for residential substance abuse treatment, an inmate must be "determined by the Bureau of Prisons to have a substance abuse problem" and be "willing to participate in [the] program." 18 U. S. C. §§3621(e)(5)(B)(i), (ii). 6 LOPEZ v. DAVIS Opinion of the Court convicted of a nonviolent offense `may be reduced by the Bureau of Prisons.' " Id., at 1094 (quoting 18 U. S. C. §3621(e)(2)(B)). This discretionary formulation, the Eighth Circuit reasoned, allows the Bureau to devise a regime based on criteria that can be uniformly applied. The statute grants no entitlement to any inmate or class of inmates, the Court of Appeals noted, and it does not instruct the Bureau to make "individual, rather than categorical, assessments of eligibility for inmates con- victed of nonviolent offenses." 186 F. 3d, at 1094. The court further reasoned that, to the extent Congress left a gap in §3621(e)(2)(B) for the Bureau to fill, deference is owed the BOP's interpretation under Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 843­845, 866 (1984), so long as the interpretation is a per- missible construction of the statute. 186 F. 3d, at 1095. The Bureau had elected to deny early release to certain catego- ries of prisoners, notably recidivists and firearms carriers, whose "conduct indicates that they pose a serious risk to public safety." Ibid. That decision, the Court of Appeals concluded, "represents a manifestly permissible construction of the statute and an appropriate exercise of the BOP's discretion." Ibid. The Eighth Circuit next explained why its earlier deci- sion in Martin did not control this case, which trains on the BOP's 1997 regulation: Martin addressed only the Bureau's 1995 attempt to interpret the statutory term "nonviolent offense"; the court in that case did not address "whether the BOP may, as an exercise of its discretion, . . . look to sentencing factors in deciding which individuals among statutorily eligible inmates are appropriate candi- dates for early release." 186 F. 3d, at 1095. Facing that issue, the Court of Appeals held such an exercise of discre- tion proper. Ibid. The Courts of Appeals have again divided, now over the permissibility of the Bureau's current (1997) regulation. Cite as: 531 U. S. ____ (2001) 7 Opinion of the Court The Tenth and Eleventh Circuits, in line with their prior decisions invalidating the 1995 rule, have concluded that §3621(e)(2)(B) permits no categorical exclusions of non- violent offenders based on sentence enhancements. Ward v. Booker, 202 F. 3d 1249, 1256­1257 (CA10 2000); Kilpa- trick v. Houston, 197 F. 3d 1134, 1135 (CA11 1999). The Ninth Circuit, on the other hand, has agreed with the Eighth Circuit that precedent invalidating the 1995 rule does not control and that, in 1997, the BOP permissibly exercised its discretion under §3621(e)(2)(B) when it cate- gorically excluded from early release consideration in- mates who possessed a firearm in connection with their nonviolent offenses. Bowen v. Hood, 202 F. 3d 1211, 1218­1220 (2000). We granted certiorari to resolve this conflict, 529 U. S. 1086 (2000), and now affirm the judgment of the Eighth Circuit. II The statute provides: "The period a prisoner convicted of a nonviolent offense remains in custody after successfully completing a treatment program may be reduced by the Bureau of Prisons . . . ." 18 U. S. C. §3621(e)(2)(B). The measure thus categorically denies early release eligibility to inmates convicted of violent offenses. The question we address is whether the Bureau has discretion to delineate, as an additional category of ineligible inmates, those whose current offense is a felony involving a firearm. 28 CFR §550.58(a)(1)(vi)(B) (2000). Lopez urges that the statute is unambiguous. He says that, by identifying a class of inmates ineligible for sen- tence reductions under §3621(e)(2)(B), i.e., those convicted of a violent offense, Congress has barred the Bureau from identifying further categories of ineligible inmates. "If Congress wanted the BOP to reduce the categories of inmates eligible for the early release incentive (beyond the 8 LOPEZ v. DAVIS Opinion of the Court one identified by Congress), Congress would have specifi- cally placed this grant of authority in the language of the statute." Brief for Petitioner 23. As to the statutory i n- struction that the Bureau "may" reduce sentences, Lopez initially suggests it is merely a grant of authority to the BOP to reduce a sentence that, prior to the enactment of §3621(e)(2)(B), could not be reduced for successful comple- tion of drug treatment: "The power granted was to give reductions not the power to decide who was eligible to receive reductions." Id., at 21. He alternately contends that the Bureau may take into account only "post- conviction conduct," not "pre-conviction conduct." Reply Brief 4­5. Acting on a case-by-case basis, Lopez asserts, the Bureau may "deny early release to those inmates [who] are statutorily eligible, but who do not deserve early release based on their conduct while in prison." Id., at 5. Under this reading, the Bureau may exercise discretion in denying early release, but only on an individual basis, taking account solely of postconviction conduct. In the Bureau's view, §3621(e)(2)(B) establishes two prerequisites for sentence reduction: conviction of a non- violent offense and successful completion of drug treat- ment. Brief for Respondents 18. If those prerequisites are met, the Bureau "may," but also may not, grant early release. The BOP opposes Lopez's argument that Con- gress barred the Bureau from imposing limitations cate- gorically or on the basis of preconviction conduct. Ac- cording to the Bureau, Congress simply "did not address how the Bureau should exercise its discretion within the class of inmates who satisfy the statutory prerequisites for early release." Id., at 23. Because Congress left the ques- tion unaddressed, the Bureau maintains, the agency may exclude inmates either categorically or on a case-by-case basis, subject of course to its obligation to interpret the statute reasonably, see Chevron, 467 U. S., at 844, in a manner that is not arbitrary or capricious, see 5 U. S. C. Cite as: 531 U. S. ____ (2001) 9 Opinion of the Court §706(2)(A). In this instance, the Bureau urges, it has acted reasonably: Its denial of early release to all inmates who possessed a firearm in connection with their current offense rationally reflects the view that such inmates displayed a readiness to endanger another's life; accord- ingly, in the interest of public safety, they should not be released months in advance of completing their sentences.3 We agree with the Bureau's position. Preliminarily, we note conspicuous anomalies in Lopez's construction. If §3621(e)(2)(B) functions not as a grant of discretion to determine early release eligibility, but both as an authori- zation and a command to reduce sentences, then Congress' use of the word "may," rather than "shall," has no signifi- cance. And if the BOP does have discretion to deny early release to certain inmates, but only based on individual- ized assessments of postconviction conduct, then the agency cannot categorically deny early release even to recidivists with prior (perhaps multiple) convictions for "homicide, forcible rape . . . , or child sexual abuse of- fenses." 28 CFR §550.58(a)(1)(iv) (2000). For that provi- sion, as much as the exclusion of inmates imprisoned for offenses involving a firearm, see supra, at 4, entails no individualized determination based on postconviction conduct. Furthermore, Lopez's position would confine the BOP's discretion under §3621(e)(2)(B) to consideration of factors of the kind the Bureau already may consider in - - - - - - 3 The dissent straddles the fence, agreeing with Lopez that the stat- ute addresses his case unambiguously, but disagreeing with him on precisely what the statute says. Lopez reads the statute to exclude Bureau consideration of preconviction conduct, Reply Brief 4­5; the dissent reads the same words to permit BOP consideration of such conduct, post, at 4 (STEVENS, J., dissenting). These divergent readings hardly strengthen the dissent's assertion that Congress supplied a definitive answer to the "precise question" at issue. See post, at 1. 10 LOPEZ v. DAVIS Opinion of the Court granting credit for "satisfactory behavior." See 18 U. S. C. §3624(b)(1) ("a prisoner [serving a term of more than one year and less than life] may receive credit toward the service of the prisoner's sentence . . . subject to determina- tion by the Bureau of Prisons that, during that year, the prisoner has displayed exemplary compliance with such institutional disciplinary regulations"). We turn now to the Bureau's reading of the statutory text, which instructs that the agency "may" reduce the sentence of a nonviolent offender who has successfully completed a drug treatment program. Congress' use of the permissive "may" in §3621(e)(2)(B) contrasts with the legislators' use of a mandatory "shall" in the very same section. Elsewhere in §3621, Congress used "shall" to impose discretionless obligations, including the obligation to provide drug treatment when funds are available. See 18 U. S. C. §3621(e)(1) ("Bureau of Prisons shall, subject to the availability of appropriations, provide residential substance abuse treatment (and make arrangements for appropriate aftercare)"); see also, e.g., §3621(b) ("The Bureau shall designate the place of the prisoner's impris- onment. . . . In designating the place of imprisonment or making transfers under this subsection, there shall be no favoritism given to prisoners of high social or economic status."). Sensibly read, the grant of discretion in §3621(e)(2)(B) to decide whether to reduce a sentence parallels the grant of discretion in §3621(e)(2)(A) to retain a prisoner who successfully completes drug treatment "under such [custodial] conditions as the Bureau deems appropriate." §3621(e)(2)(A). When an eligible prisoner successfully completes drug treatment, the Bureau thus has the authority, but not the duty, both to alter the pris- oner's conditions of confinement and to reduce his term of imprisonment. The constraints Lopez urges- requiring the BOP to make individualized determinations based only on post- Cite as: 531 U. S. ____ (2001) 11 Opinion of the Court conviction conduct- are nowhere to be found in §3621(e)(2)(B). Beyond instructing that the Bureau has discretion to reduce the period of imprisonment for a nonviolent offender who successfully completes drug treatment, Congress has not identified any further cir- cumstance in which the Bureau either must grant the reduction, or is forbidden to do so. In this familiar situa- tion, where Congress has enacted a law that does not answer "the precise question at issue," all we must decide is whether the Bureau, the agency empowered to adminis- ter the early release program, has filled the statutory gap "in a way that is reasonable in light of the legislature's revealed design." NationsBank of N. C., N. A. v. Variable Annuity Life Ins. Co., 513 U. S. 251, 257 (1995) (citing Chevron, 467 U. S., at 842); see also Reno v. Koray, 515 U. S. 50, 61 (1995) (deferring to BOP's interpretation of statute). We think the agency's interpretation is reason- able both in taking account of preconviction conduct and in making categorical exclusions. First, as the dissent but not Lopez recognizes, see post, at 4, the Bureau need not blind itself to preconviction conduct that the agency reasonably views as jeopardizing life and limb. By denying eligibility to violent offenders, the statute manifests congressional concern for preconvic- tion behavior- and for the very conduct leading to convic- tion. The Bureau may reasonably attend to these factors as well. Its regulation in this regard is kin to the Attorney General's order upheld in INS v. Yueh-Shaio Yang, 519 U. S. 26 (1996). That case involved a statute authorizing the Attorney General to waive deportation of aliens de- portable for entry fraud. The Attorney General had re- fused to waive deportation for one alien because of "acts of fraud . . . in connection with his entry." Id., at 27. The alien argued that because the statute made aliens who had committed entry fraud eligible for waiver, the Attor- ney General was precluded from taking such conduct into 12 LOPEZ v. DAVIS Opinion of the Court account "at all" in deciding whether to grant relief. Id., at 30. We rejected this view, stating that the statute "esta b- lishes only the alien's eligibility for the waiver. Such eligibility in no way limits the considerations that may guide the Attorney General in exercising her discretion to determine who, among those eligible, will be accorded grace." Id., at 31. Similarly in this case, the statute's restriction of early release eligibility to nonviolent offend- ers does not cut short the considerations that may guide the Bureau. Just as the Attorney General permissibly considered aspects of entry fraud, even though entry fraud was a criterion of statutory eligibility, so the Bureau may consider aspects of the conduct of conviction, even though the conviction is a criterion of statutory eligibility.4 We also reject Lopez's argument, echoed in part by the dissent, post, at 5, that the agency must not make cate- gorical exclusions, but may rely only on case-by-case as- - - - - - - 4 Lopez contends that the Bureau's creation of additional hurdles to receipt of a sentence reduction defeats Congress' purpose of giving inmates an incentive to undergo drug treatment. Brief for Petitioner 24­29. In INS v. Yueh-Shaio Yang, 519 U. S. 26 (1996), we said that "[i]t could be argued that if the Attorney General determined that any entry fraud or misrepresentation, no matter how minor and no matter what the attendant circumstances, would cause her to withhold waiver, she would not be exercising the conferred discretion at all, but would be making a nullity of the statute." Id., at 31. In this case, it is plain that the Bureau has not rendered §3621(e)'s incentive a nullity. A total of 6,559 inmates have received sentence reductions under §3621(e)(2)(B), including 2,633 inmates in Fiscal Year 1999 alone. Bureau of Prisons, Substance Abuse Treatment Programs in the Federal Bureau of Prisons, Report to Con- gress 8 (Jan. 2000). Moreover, inmates who do not qualify for early release, like inmates who do, receive other incentives to participate in substance abuse treatment. See 28 CFR §§550.57(a)(1), (3) (2000) ("An inmate may receive incentives for his or her satisfactory involvement in the residential [drug treatment] program," including "[l]imited financial awards" and "[l]ocal institution incentives such as preferred living quar- ters or special recognition privileges."). Cite as: 531 U. S. ____ (2001) 13 Opinion of the Court sessments.5 "[E]ven if a statutory scheme requires indi- vidualized determinations," which this scheme does not, "the decisionmaker has the authority to rely on rulemak- ing to resolve certain issues of general applicability unless Congress clearly expresses an intent to withhold that authority." American Hospital Assn. v. NLRB, 499 U. S. 606, 612 (1991); accord, Heckler v. Campbell, 461 U. S. 458, 467 (1983). The approach pressed by Lopez- case- by-case decisionmaking in thousands of cases each year, see supra, 12, n. 4- could invite favoritism, disunity, and inconsistency. The Bureau is not required continually to revisit "issues that may be established fairly and effi- ciently in a single rulemaking proceeding." Heckler, 461 U. S., at 467.6 Having decided that the Bureau may categorically exclude prisoners based on their preconviction conduct, we further hold that the regulation excluding Lopez is per- missible. The Bureau reasonably concluded that an in- mate's prior involvement with firearms, in connection with the commission of a felony, suggests his readiness to resort to life-endangering violence and therefore appropri- ately determines the early release decision.7 - - - - - - 5 The dissent appears to acknowledge that the Bureau may give "near-dispositive weight to preconviction criteria." Post, at 6. To the extent the dissent would permit the BOP to accord heavy weight to pre- conviction conduct, the structured "[i]ndividualized [BOP] considera- tion" the dissent would allow, post, at 5, seems but a shade different from the forthright categorical exclusion the Bureau has adopted. 6 Amici urge reversal on the ground that the Bureau violated the notice and comment requirements of the Administrative Procedure Act when it published the 1997 regulation. Brief for National Association of Criminal Defense Lawyers et al. as Amici Curiae 18­24. We decline to address this matter, which was not raised or decided below, or presented in the petition for certiorari. Blessing v. Freestone, 520 U. S. 329, 340, n. 3 (1997). 7 Lopez invokes the rule of lenity in urging us to accede to his interpre- tation. Because, as discussed above, the statute cannot be read to prohibit 14 LOPEZ v. DAVIS Opinion of the Court For the reasons stated, the judgment of the Court of Appeals for the Eighth Circuit is Affirmed. - - - - - - the Bureau from exercising its discretion categorically or on the basis of preconviction conduct, his reliance on the rule is unavailing. See Caron v. United States, 524 U. S. 308, 316 (1998) ("The rule of lenity is not invoked by a grammatical possibility. It does not apply if the ambiguous reading relied on is an implausible reading of the congressional purpose."). Cite as: 531 U. S. ____ (2001) 1 STEVENS, J., dissenting SUPREME COURT OF THE UNITED STATES _________________ No. 99­7504 _________________ CHRISTOPHER A. LOPEZ, PETITIONER v. RANDY J. DAVIS, WARDEN, ET AL. ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE EIGHTH CIRCUIT [January 10, 2001] JUSTICE STEVENS, with whom THE CHIEF JUSTICE and JUSTICE KENNEDY join, dissenting. The question at issue in this case is whether all, or merely some, of the federal prisoners who were convicted of nonviolent offenses and who have successfully com- pleted a Bureau of Prisons (BOP) drug treatment program are eligible for a sentence reduction pursuant to 18 U. S. C. §3621(e)(2)(B). For the reasons outlined below, I believe that Congress has answered that precise question. The statute expressly states that the sentence of every prisoner in that category "may be reduced." Ibid. The disposition of this case is therefore governed by the first step in the familiar test announced in Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 842­843 (1984), for "Congress has directly spoken to the precise question at issue." Id., at 842. I In drafting the statute in question, Congress was faced with a difficult policy choice: whether the commis- sion of particular crimes made certain categories of of- fenders so dangerous that the costs of offering them early release in return for the successful completion of a drug treatment program outweighed the rewards. The initial drafts of the bill answered that question in the negative 2 LOPEZ v. DAVIS STEVENS, J., dissenting and made all federal prisoners eligible for a sentence reduction of up to one year if they successfully completed a drug treatment program. See, e.g., H. R. Rep. No. 103­ 320, p. 2 (1993). However, the inclusion of those convicted of violent offenses within the category of those eligible for the inducement soon became a fulcrum of criticism for the larger crime bill within which the statute was embedded.1 Perhaps as a result of these criticisms, 2 the statute ultimately adopted limited the inducement to "pris- oner[s] convicted of . . . nonviolent offense[s]." 18 U. S. C. §3621(e)(2)(B). Both the text of the statute and the aforementioned history demonstrate that Congress directly addressed the - - - - - - 1Throughout 1993 and 1994, Republican leaders gave numerous speeches contrasting their proposed crime bill and the administration's. One contrast repeatedly stressed was that the Republican bill set aside more money for prison construction while the Democratic bill allocated greater funds to drug treatment. This difference allegedly reflected differing views as to how society should deal with violent criminals. To this end, Republican leaders repeatedly criticized the inclusion of violent criminals in the sentence reduction provision. See, e.g., 139 Cong. Rec. 27209 (1994) (remarks of Sen. Hatch) ("Their treatment allows all Federal prisoners, including the most violent, to have their sentences reduced, if you will, at the Bureau of Prisons' discretion if they complete a drug treatment program. Boy, I can see where every- body is going to do that. You can imagine the sincerity of that"); 139 Cong. Rec. 27460 (1994) (remarks of Sen. Hatch) ("The Democratic crime bill actually permits the Bureau of Prisons to decrease the sentence of Federal inmates- violent offenders included- who complete drug treatment programs. Their bill also proposes that States be given grant money which can be used to implement home confinement and other alternative sanctions for violent offenders"). 2 The House initially approved a version of the bill that would have extended the inducement to all federal prisoners. The Senate, where the criticism of the inclusion of violent offenders was more pronounced, see n. 1, supra, limited the provision to nonviolent offenders. The Conference Committee accepted the Senate's limitation. H. R. Conf. Rep. No. 103­711, p. 381 (1994). Cite as: 531 U. S. ____ (2001) 3 STEVENS, J., dissenting "precise question" of what offenses ought to disqualify prisoners from eligibility for a sentence reduction, and that its unambiguous answer was "violent offenses." Under the statute as enacted, those who commit crimes of violence are categorically barred from receiving a sentence reduction while those convicted of nonviolent offenses "may" receive such an inducement. The BOP regulation challenged here operates to rede- fine the set of prisoners categorically ineligible for a sen- tence reduction, a set unambiguously defined in the text of the statute. It does so by taking a group of prisoners whose offenses the Bureau acknowledges are "nonviolent" within the meaning of the statute3 and imposing the same sanction- categorical ineligibility- upon them as the statute imposes upon violent offenders. In so doing, the Bureau ignores Congress's express determination that, when evaluating eligibility for a sentence reduction, the salient distinction is the line between violent and nonvio- lent offenses. By moving this line, the BOP exceeded its authority and sought to exercise its discretion on an issue with regard to which it has none. See, e.g., Chevron, 467 U. S., at 842­843 ("First, always, is the question whether Congress has directly spoken to the precise question at issue. If the intent of Congress is clear, that is the end of the matter; for the court, as well as the agency, must give - - - - - - 3 The BOP regulation challenged here treats an otherwise nonviolent offense where a gun was carried as a "nonviolent offense" within the meaning of the statute, and the case was argued on that assumption. As the majority notes, ante, at 2­4, the BOP initially attempted to classify such crimes as violent offenses, but receded when the Courts of Appeals divided over the validity of such a construction. The question over which the Courts of Appeals initially divided is not before us today. If it were, the arguments raised by both sides would be quite different, with the debate likely focusing on whether "nonviolent offense" is best understood as a term of art or in relation to a more colloquial understanding of violence. 4 LOPEZ v. DAVIS STEVENS, J., dissenting effect to the unambiguously expressed intent of Con- gress"); United States v. Haggar Apparel Co., 526 U. S. 380, 392 (1999) ("In the process of considering a regulation in relation to specific factual situations, a court may con- clude the regulation is inconsistent with the statutory language or is an unreasonable implementation of it. In those instances, the regulation will not control"). II I fully agree with the majority that federal prisoners do not become entitled to a sentence reduction upon their successful completion of a drug treatment program; the words "may be reduced" do not mean "shall be reduced." Nonetheless, while the statute does not entitle any pris- oner to a sentence reduction, it does guarantee nonviolent offenders who successfully complete a drug treatment program consideration for such a reduction. For every nonviolent offender who participates in a drug treatment program, the BOP may be required to make two individualized determinations: (1) whether he or she has successfully completed that program; and (2), if so, whether his or her preconviction conduct, postconviction conduct, and prospects for rehabilitation justify a sentence reduction. In evaluating whether or not a particular individual is entitled to a sentence reduction, the BOP may give great weight to whichever of these factors it determines to be most relevant. That, however, is a far cry from categorically excluding from consideration pris- oners who Congress explicitly intended to obtain such consideration.4 - - - - - - 4 This Court's decision in INS v. Yueh-Shaio Yang, 519 U. S. 26 (1996), relied upon by the majority, ante, at 11, is not to the contrary. Yueh-Shaio Yang did not involve an effort by an administrative agency to categorically exclude from consideration for a benefit a particular class of individuals because of a characteristic considered and rejected Cite as: 531 U. S. ____ (2001) 5 STEVENS, J., dissenting The majority's concern about the risks and burdens associated with case-by-case decisionmaking in a large number of cases is understandable yet ultimately mis- guided. In order to fulfill the statute's requirements, the BOP must already evaluate every prisoner seeking the sentence reduction on an individual basis to determine whether that prisoner "successfully completed" his or her drug treatment program. Individualized consideration of the second salient question involves consideration of many of the same personalized factors that go into determining whether a prisoner's course of drug treatment has been "successful." To the extent that answering the second question requires consideration of additional factors with a concomitant administrative burden, the costs of such a scheme are, in Congress's judgment, outweighed by the benefits of encouraging drug treatment and of carefully distinguishing between those prisoners who have earned an early return to their communities and those who re- quire further incarceration. The majority's worry that individualized decisionmaking might lead to "favoritism, disunity, and inconsistency" is similarly misplaced. Ante, at 13. To suggest that deci- sionmaking must be individualized is not to imply that it must also be standardless. If the Court today invalidated the regulation in question, its decision would not preclude the BOP from adopting a uniform set of criteria for consid- eration in evaluating applications for sentence reductions. - - - - - - by Congress as a basis for categorical exclusion. Rather, that case involved the related yet distinct question whether such a characteristic may be given any weight by the agency in making an individualized case-by-case determination whether to grant the benefit to a particular individual. If the issue in this case were whether the BOP could even consider the nature of the offense in determining whether to grant a particular sentence reduction, Yueh-Shaio Yang would be relevant to our analysis. 6 LOPEZ v. DAVIS STEVENS, J., dissenting Nor would it necessarily preclude the Bureau from giving dispositive weight to certain postconviction criteria or near-dispositive weight to preconviction criteria. Cf. Heckler v. Campbell, 461 U. S. 458, 467 (1983). The B u- reau would remain free to structure its decisionmaking in any way it saw fit as long as in so doing it did not contra- vene policy decisions explicitly made by the statute's drafters. As Congress has already addressed preincar- ceration conduct in §3621(e)(2)(B), the Bureau may not categorically exclude a prisoner not convicted of a violent offense from consideration for early release on the basis of such conduct without exceeding the limits of its discretion. Accordingly, I respectfully dissent.