LOPEZ v. DAVIS, WARDEN, et al.

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230 OCTOBER TERM, 2000
Syllabus
LOPEZ v. DAVIS, WARDEN, et al.
certiorari to the united states court of appeals for
the eighth circuit
No. 99–7504. 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 com-
pleting a [substance abuse] treatment program may be reduced by the
Bureau of Prisons” (BOP). The BOP therefore ranked ineligible for
early release all inmates incarcerated for “crime[s] of violence.” Ini-
tially, the BOP defined the term “crimes of violence” to include, among
other offenses, a drug trafficking conviction under 21 U. S. C. § 841, if
the offender received a two-level sentence enhancement under United
States Sentencing Commission, Guidelines Manual (USSG) § 2D1.1(b)(1),
for possessing a dangerous weapon in connection with the drug offense.
The Courts of Appeals thereafter divided over the validity of classifying
drug offenses involving firearms possession as crimes of violence. The
Circuit division prompted the BOP to issue the regulation now before
the Court. That regulation denies early release to several categories
of prisoners, including inmates whose current offense is a felony at-
tended 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 distribute
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 release, the District
Court held that the BOP may not categorically count out, based upon
sentencing factors or weapon possession, inmates 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 Congress left a gap in § 3621(e)(2)(B)
for the BOP to fill, the Court of Appeals stated, deference is owed the
BOP’s interpretation under Chevron U. S. A. Inc. v. Natural Resources

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231 Cite as: 531 U. S. 230 (2001)
Syllabus
Defense Council, Inc., 467 U. S. 837, 843–845, 866, so long as the inter-
pretation is a permissible construction of the statute. The BOP’s de-
cision to deny early release to drug traffickers who carry firearms, the
court concluded, represents a manifestly permissible statutory construc-
tion and an appropriate exercise of discretion.
Held: The regulation at issue is a permissible exercise of the BOP’s discre-
tion under § 3621(e)(2)(B). Pp. 238–245.
(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 discretion
is to be exercised. If an inmate meets the two statutory prerequisites
for sentence reduction—conviction of a nonviolent offense and success-
ful completion of drug treatment—then § 3621(e)(2)(B) instructs 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 manda-
tory “shall” elsewhere in § 3621 to impose discretionless 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 dis-
cretion parallels the grant of discretion in § 3621(e)(2)(A) to retain a
prisoner who successfully completes drug treatment “under such [cus-
todial] conditions as the [BOP] deems appropriate.” 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 re-
duce the period of imprisonment for a nonviolent offender who success-
fully completes drug treatment, Congress has not identified any further
circumstance in which the BOP either must grant the reduction, or is
forbidden to do so. In this familiar situation, where Congress has en-
acted a law that does not answer the precise question at issue, all this
Court must decide is whether the BOP, the agency empowered to ad-
minister the early release program, has filled the statutory gap in a
way that is reasonable 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. 238–242.
(b) The BOP may categorically exclude prisoners from early release
eligibility based on their preconviction conduct. The Court rejects Lo-
pez’s argument that the BOP may take into account only postconviction
conduct. The BOP 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 con-
cern for preconviction behavior—and for the very conduct leading to
conviction. The BOP may reasonably attend to these factors as well.
The statute’s restriction of early release eligibility to nonviolent offend-

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232 LOPEZ v. DAVIS
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ers 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 argument that the BOP must
not make categorical exclusions, but may rely only on case-by-case
assessments. Even if a statutory scheme requires individualized de-
terminations, which this scheme does not, the decisionmaker has the
authority to rely on rulemaking to resolve certain issues of general
applicability unless Congress clearly expresses an intent to withhold
that authority. E. g., Heckler v. Campbell, 461 U. S. 458, 467. The ap-
proach pressed by Lopez—case-by-case decisionmaking in thousands of
cases each year—could invite favoritism, disunity, and inconsistency.
Pp. 242–244.
(c) The regulation excluding Lopez is permissible. The BOP reason-
ably concluded that an inmate’s prior involvement with firearms, in con-
nection with the commission of a felony, suggests his readiness to resort
to life-endangering violence and therefore appropriately determines the
early release decision. P. 244.
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,
post, p. 245.
Mark V. Meierhenry argued the cause and filed briefs for
petitioner.
Beth S. Brinkmann argued the cause for respondents.
With her on the brief were Solicitor General Waxman, As-
sistant Attorney General Robinson, and Deputy Solicitor
General Dreeben.*
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 non-
violent felony, if the prisoner successfully completes a sub-
stance abuse program. The Bureau’s implementing regula-
*Stephen R. Sady filed a brief for the National Association of Criminal
Defense Lawyers et al. as amici curiae urging reversal.

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Opinion of the Court
tion categorically denies early release to prisoners whose
current offense is a felony attended by “the carrying, pos-
session, or use of a firearm.” 28 CFR § 550.58(a)(1)(vi)(B)
(2000). The validity of the Bureau’s regulation is the ques-
tion 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 Bureau’s discretion under
18 U. S. C. § 3621(e)(2)(B).
I
A
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 con-
dition 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 incen-
tive provision at issue reads: “The period a prisoner con-
victed of a nonviolent offense remains in custody after suc-
cessfully 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 other-
wise serve.” Pub. L. 103–322, § 32001, 108 Stat. 1897 (codi-
fied 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. 27692–27695; 28 CFR
§ 550.58. Because the statute explicitly confined the incen-
tive 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 vi-
olence,” 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,

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234 LOPEZ v. DAVIS
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if the offender received a two-level sentence enhancement
under United States Sentencing Commission, Guidelines
Manual (USSG) § 2D1.1(b)(1) (Nov. 2000), 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 17–18.1
“[E]xercising [its] discretion in reducing a sentence,” the Bu-
reau 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 Bu-
reau’s definition of crimes of violence to include drug offenses
that involved possession of a firearm. A majority of Cir-
cuits, including the Eighth, held that § 3621(e)(2)(B) required
the Bureau to look only to the offense of conviction (drug
trafficking), and not to sentencing factors (firearm posses-
sion), 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. Thomp-
son, 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
1 Title 21 U. S. C. §§ 841(a)(1) and (2) make it unlawful “to manufacture,
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 counterfeit 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 com-
ment., n. 3 (Nov. 2000).

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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. 53690–53691. Like the 1995 rule, the current regula-
tion 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 sentence reduction to ex-
clude [enumerated categories of] inmates.” Id., at 53690.
The regulation, designed to achieve consistent administra-
tion of the incentive, now provides:
“(a) Additional early release criteria. (1) As an ex-
ercise of the discretion vested in the Director of the
Federal Bureau of Prisons, the following categories of
inmates are not eligible for early release:
. . . . .
“(iv) Inmates who have a prior felony or misdemeanor
conviction for homicide, forcible rape, robbery, or aggra-
vated 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 “prisoner
convicted of a nonviolent offense” to exclude categorically an
inmate who possessed a firearm in connection with his of-
fense. The current regulation categorically excludes such
an inmate, not because § 3621(e)(2)(B) so mandates, but pur-

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236 LOPEZ v. DAVIS
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suant to the Bureau’s asserted discretion to prescribe addi-
tional early release criteria. Drug traffickers who possess
firearms when they engage in crimes are no longer charac-
terized as “violent” offenders within the meaning of the stat-
ute. But they are bracketed, for sentence reduction pur-
poses, with persons currently incarcerated for “nonviolent
offense[s]” who in the past committed crimes qualifying as
violent. The preconviction conduct of both armed offenders
and certain redicivists, in the Bureau’s view, “suggest[s] that
they pose a particular risk to the public.” Brief for Re-
spondents 30.
B
In 1997, petitioner Christopher A. Lopez was convicted
of possession with intent to distribute methamphetamine, in
violation of 21 U. S. C. § 841. Upon finding that Lopez pos-
sessed a firearm in connection with his offense, the District
Court enhanced his sentence by two levels pursuant 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 residen-
tial 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 regulation did not
correct the infirmity the Eighth Circuit saw in the 1995 rule.
See App. 17–18, and n. 4 (citing Martin, 133 F. 3d, at 1079).
“[I]t is true,” the District Court recognized, “that the BOP
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).

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may exercise a great deal of discretion 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 eligi-
bility for early release.” 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
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 convicted 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, 843–845, 866 (1984), so long as the inter-
pretation is a permissible construction of the statute. 186
F. 3d, at 1095. The Bureau had elected to deny early release
to certain categories 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 per-
missible construction of the statute and an appropriate exer-
cise of the BOP’s discretion.” Ibid.
The Eighth Circuit next explained why its earlier decision
in Martin did not control this case, which trains on the BOP’s
1997 regulation: Martin addressed only the Bureau’s 1995

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238 LOPEZ v. DAVIS
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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 eligi-
ble inmates are appropriate candidates for early release.”
186 F. 3d, at 1095. Facing that issue, the Court of Appeals
held such an exercise of discretion proper. Ibid.
The Courts of Appeals have again divided, now over the
permissibility of the Bureau’s current (1997) regulation.
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 nonvio-
lent offenders based on sentence enhancements. Ward v.
Booker, 202 F. 3d 1249, 1256–1257 (CA10 2000); Kilpatrick
v. Houston, 197 F. 3d 1134, 1135 (CA11 1999). The Ninth
Circuit, on the other hand, has agreed with the Eighth Cir-
cuit 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 categorically ex-
cluded from early release consideration inmates who pos-
sessed a firearm in connection with their nonviolent offenses.
Bowen v. Hood, 202 F. 3d 1211, 1218–1220 (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).

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Lopez urges that the statute is unambiguous. He says
that, by identifying a class of inmates ineligible for sentence
reductions under § 3621(e)(2)(B), i. e., those convicted of a
violent offense, Congress has barred the Bureau from identi-
fying further categories of ineligible inmates. “If Congress
wanted the BOP to reduce the categories of inmates eligible
for the early release incentive (beyond the one identified by
Congress), Congress would have specifically placed this
grant of authority in the language of the statute.” Brief for
Petitioner 23. As to the statutory instruction that the Bu-
reau “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 completion of drug treatment: “The
power granted was to give reductions not the power to de-
cide 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 4–5. Acting on a case-by-case basis, Lopez as-
serts, 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 pre-
requisites for sentence reduction: conviction of a nonviolent
offense and successful completion of drug treatment. Brief
for Respondents 18. If those prerequisites are met, the Bu-
reau “may,” but also may not, grant early release. The BOP
opposes Lopez’s argument that Congress barred the Bureau
from imposing limitations categorically or on the basis of
preconviction conduct. According to the Bureau, Congress
simply “did not address how the Bureau should exercise its
discretion within the class of inmates who satisfy the statu-
tory prerequisites for early release.” Id., at 23. Because

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240 LOPEZ v. DAVIS
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Congress left the question unaddressed, the Bureau main-
tains, 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. § 706(2)(A). In this instance, the Bureau urges,
it has acted reasonably: Its denial of early release to all in-
mates who possessed a firearm in connection with their cur-
rent offense rationally reflects the view that such inmates
displayed a readiness to endanger another’s life; accordingly,
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 de-
termine early release eligibility, but both as an authorization
and a command to reduce sentences, then Congress’ use of
the word “may,” rather than “shall,” has no significance.
And if the BOP does have discretion to deny early release
to certain inmates, but only based on individualized as-
sessments 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 offenses.” 28 CFR
§ 550.58(a)(1)(iv) (2000). For that provision, as much as the
exclusion of inmates imprisoned for offenses involving a
firearm, see supra, at 235, entails no individualized deter-
mination based on postconviction conduct. Furthermore,
3 The dissent straddles the fence, agreeing with Lopez that the statute
addresses his case unambiguously, but disagreeing with him on precisely
what the statute says. Lopez reads the statute to exclude Bureau con-
sideration of preconviction conduct, Reply Brief 4–5; the dissent reads
the same words to permit BOP consideration of such conduct, post, at 248
(opinion of Stevens, J.). These divergent readings hardly strengthen the
dissent’s assertion that Congress supplied a definitive answer to the “pre-
cise question” at issue. See post, at 245.

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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 granting credit for “satis-
factory 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 sen-
tence . . . subject to determination 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 obli-
gations, including the obligation to provide drug treatment
when funds are available. See 18 U. S. C. § 3621(e)(1) (“Bu-
reau of Prisons shall, subject to the availability of appro-
priations, 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 imprisonment. . . . 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 ap-
propriate.” § 3621(e)(2)(A). When an eligible prisoner suc-
cessfully completes drug treatment, the Bureau thus has the
authority, but not the duty, both to alter the prisoner’s condi-
tions of confinement and to reduce his term of imprisonment.
The constraints Lopez urges—requiring the BOP to make
individualized determinations based only on postconviction

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242 LOPEZ v. DAVIS
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conduct—are nowhere to be found in § 3621(e)(2)(B). Be-
yond 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 circumstance in which the Bureau
either must grant the reduction, or is forbidden to do so. In
this familiar situation, 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 administer the early release program, has filled the statu-
tory gap “in a way that is reasonable in light of the legis-
lature’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
248, 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 preconviction behav-
ior—and for the very conduct leading to conviction. 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 Gen-
eral to waive deportation of aliens deportable for entry
fraud. The Attorney General had refused to waive deporta-
tion 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 eligi-
ble for waiver, the Attorney General was precluded from
taking such conduct into account “at all” in deciding whether
to grant relief. Id., at 30. We rejected this view, stating

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243 Cite as: 531 U. S. 230 (2001)
Opinion of the Court
that the statute “establishes only the alien’s eligibility for
the waiver. Such eligibility in no way limits the considera-
tions 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 stat-
ute’s restriction of early release eligibility to nonviolent of-
fenders does not cut short the considerations that may guide
the Bureau. Just as the Attorney General permissibly con-
sidered aspects of entry fraud, even though entry fraud was
a criterion of statutory eligibility, so the Bureau may con-
sider 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 248–249, that the agency must not make cat-
egorical exclusions, but may rely only on case-by-case assess-
ments.5 “[E]ven if a statutory scheme requires individual-
4 Lopez contends that the Bureau’s creation of additional hurdles to re-
ceipt of a sentence reduction defeats Congress’ purpose of giving inmates
an incentive to undergo drug treatment. Brief for Petitioner 24–29. 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 ex-
ercising 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 Treat-
ment Programs in the Federal Bureau of Prisons, Report to Congress 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 re-
ceive 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 quarters or special
recognition privileges.”).
5 The dissent appears to acknowledge that the Bureau may give “near-
dispositive weight to preconviction criteria.” Post, at 249. To the extent
the dissent would permit the BOP to accord heavy weight to preconviction

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244 LOPEZ v. DAVIS
Opinion of the Court
ized determinations,” which this scheme does not, “the
decisionmaker has the authority to rely on rulemaking to
resolve certain issues of general applicability unless Con-
gress 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, at 243, n. 4—could
invite favoritism, disunity, and inconsistency. The Bureau is
not required continually to revisit “issues that may be estab-
lished fairly and efficiently in a single rulemaking proceed-
ing.” 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 permissible.
The Bureau reasonably concluded that an inmate’s prior
involvement with firearms, in connection with the commis-
sion of a felony, suggests his readiness to resort to life-
endangering violence and therefore appropriately deter-
mines the early release decision.7
conduct, the structured “[i]ndividualized [BOP] consideration” the dissent
would allow, post, at 249, 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 Crim-
inal Defense Lawyers et al. as Amici Curiae 18–24. We decline to ad-
dress 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 pro-
hibit 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 in-
voked by a grammatical possibility. It does not apply if the ambiguous
reading relied on is an implausible reading of the congressional purpose.”).

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245 Cite as: 531 U. S. 230 (2001)
Stevens, J., dissenting
For the reasons stated, the judgment of the Court of
Appeals for the Eighth Circuit is
Affirmed.
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 non-
violent offenses and who have successfully completed a Bu-
reau of Prisons (BOP or Bureau) 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, 842–843
(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 commission of par-
ticular crimes made certain categories of offenders so dan-
gerous 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 an-
swered that question in the negative 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 be-
came a fulcrum of criticism for the larger crime bill within

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246 LOPEZ v. DAVIS
Stevens, J., dissenting
which the statute was embedded.1 Perhaps as a result of
these criticisms,2 the statute ultimately adopted limited
the inducement to “prisoner[s] convicted of . . . nonviolent
offense[s].” 18 U. S. C. § 3621(e)(2)(B).
Both the text of the statute and the aforementioned his-
tory demonstrate that Congress directly addressed the “pre-
cise question” of what offenses ought to disqualify prisoners
from eligibility for a sentence reduction, and that its unam-
biguous answer was “violent offenses.” Under the statute
as enacted, those who commit crimes of violence are cate-
gorically barred from receiving a sentence reduction while
those convicted of nonviolent offenses “may” receive such
an inducement.
1 Throughout 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 dif-
fering 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 everybody is going to do that.
You can imagine the sincerity of that”); 139 Cong. Rec. 27460 (1993) (re-
marks 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 ex-
tended 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. 103–
711, p. 381 (1994).

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247 Cite as: 531 U. S. 230 (2001)
Stevens, J., dissenting
The BOP regulation challenged here operates to redefine
the set of prisoners categorically ineligible for a sentence
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 statute 3 and imposing the same sanc-
tion—categorical ineligibility—upon them as the statute
imposes upon violent offenders. In so doing, the Bureau
ignores Congress’ express determination that, when eval-
uating eligibility for a sentence reduction, the salient dis-
tinction is the line between violent and nonviolent 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 842–843
(“First, always, is the question whether Congress has di-
rectly 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 effect to the unam-
biguously expressed intent of Congress”); 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 conclude the regulation is inconsist-
ent with the statutory language or is an unreasonable imple-
mentation of it. In those instances, the regulation will not
control”).
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 233–236, the BOP initially attempted to clas-
sify such crimes as violent offenses, but receded when the Courts of Ap-
peals 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 under-
stood as a term of art or in relation to a more colloquial understanding
of violence.

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248 LOPEZ v. DAVIS
Stevens, J., dissenting
II
I fully agree with the majority that federal prisoners do
not become entitled to a sentence reduction upon their suc-
cessful completion of a drug treatment program; the words
“may be reduced” do not mean “shall be reduced.” None-
theless, while the statute does not entitle any prisoner to a
sentence reduction, it does guarantee nonviolent offenders
who successfully complete a drug treatment program con-
sideration 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 suc-
cessfully 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 prisoners who Congress explicitly intended to
obtain such consideration.4
The majority’s concern about the risks and burdens associ-
ated with case-by-case decisionmaking in a large number of
cases is understandable yet ultimately misguided. In order
to fulfill the statute’s requirements, the BOP must already
4 This Court’s decision in INS v. Yueh-Shaio Yang, 519 U. S. 26 (1996),
relied upon by the majority, ante, at 242–243, 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 by Con-
gress 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 deter-
mination 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 reduc-
tion, Yueh-Shaio Yang would be relevant to our analysis.

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Stevens, J., dissenting
evaluate every prisoner seeking the sentence reduction on
an individual basis to determine whether that prisoner “suc-
cessfully completed” his or her drug treatment program.
Individualized consideration of the second salient question
involves consideration of many of the same personalized fac-
tors 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 ad-
ditional factors with a concomitant administrative burden,
the costs of such a scheme are, in Congress’ judgment, out-
weighed 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
require further incarceration.
The majority’s worry that individualized decisionmaking
might lead to “favoritism, disunity, and inconsistency” is
similarly misplaced. Ante, at 244. 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.
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 Bureau would re-
main free to structure its decisionmaking in any way it
saw fit as long as in so doing it did not contravene policy
decisions explicitly made by the statute’s drafters. As Con-
gress has already addressed preincarceration 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 exceed-
ing the limits of its discretion.
Accordingly, I respectfully dissent.