Jimmy Perez-Olivo v. Ricardo E. Chavez, Warden, M.d.c. Guaynabo

United States Court of Appeals
For the First Circuit
No. 04-1486
JIMMY PEREZ-OLIVO,
Petitioner, Appellant,
v.
RICARDO E. CHAVEZ, WARDEN, M.D.C. GUAYNABO,
Respondent, Appellee.
APPEAL FROM THE UNITED STATES DISTRICT COURT
FOR THE DISTRICT OF PUERTO RICO
[Hon. Carmen Consuelo Cerezo, U.S. District Judge]
Before
Lynch, Circuit Judge,
Campbell, Senior Circuit Judge,
and Stahl, Senior Circuit Judge.
Judith H. Mizner, Assistant Federal Public Defender, by
appointment of the court, for appellant.
Jimmy Perez-Olivo, on brief, pro se.
Nelson Perez-Sosa, Assistant United States Attorney, with whom
H. S. Garcia, United States Attorney, was on brief for appellee.
January 7, 2005

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STAHL, Senior Circuit Judge. Jimmy Perez-Olivo ("Perez-
Olivo") appeals the denial of his petition for a Writ of Habeas
Corpus filed under 18 U.S.C. § 2241. He alleges that the Bureau of
Prisons ("BOP") has wrongly interpreted 18 U.S.C. § 3624(b)(1),
thereby depriving him of the possibility to earn a maximum of
fifty-four days of good conduct time for each of the ten years he
has been sentenced to serve. Finding the GCT statute to be
ambiguous under Chevron U.S.A., Inc. v. Natural Res. Def. Council,
Inc., 467 U.S. 837 (1984), and the BOP's interpretation reasonable,
we affirm the decision of the district court.
I. BACKGROUND
Petitioner-appellant Perez-Olivo is currently serving
year nine of a ten-year sentence, imposed after he pleaded guilty
to one count of violating 21 U.S.C. § 841(a)(1) (possession with
intent to distribute two kilograms of cocaine), and one count of
violating 18 U.S.C. § 924(c)(1) (possession of a firearm in
relation to a drug trafficking crime). For each year of his
incarceration, Perez-Olivo has earned the maximum amount of "good
conduct time" ("GCT") available under the GCT statute, 18 U.S.C. §
3624(b), as interpreted by the BOP. The BOP estimates that if
Perez-Olivo continues this good conduct, he will earn a total of
470 days GCT to be credited towards his ten-year sentence. This
calculation is based on fifty-four days of earned GCT per year for
each complete year Perez-Olivo actually has served, plus a prorated

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1 To remove this from the abstract, assume a prisoner is
sentenced to ten years' imprisonment. At the end of year one, if
the prisoner has "displayed exemplary compliance," the BOP may
award him up to a maximum of fifty-four days of GCT. Assume this
exemplary compliance continues for the next seven years. At the
end of year eight, our model prisoner has earned a total of 432
days of GCT (fifty-four days per year for eight years). This means
that, at a minimum, the prisoner will not serve any of year ten.
In addition, the prisoner will not serve all of year nine (432 -
365 days not served in year 10 = 67 days in year nine that will not
be served).
In order to calculate the prisoner's estimated GCT for year
nine, we look to the statute, which instructs us that "credit for
the last year or portion of a year of the term of imprisonment
shall be prorated." See 18 U.S.C. § 3624(b)(1). Since the
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amount of GCT for the last portion of the year he actually serves.
Perez-Olivo alleges, however, that he is entitled to 540 days of
GCT under 18 U.S.C. § 3624(b)(1). This difference arises from the
fact that the BOP calculates GCT based on the time the prisoner
actually serves, and Perez-Olivo urges that 18 U.S.C. § 3624(b)(1)
requires that GCT be calculated based on the time the prisoner is
sentenced to serve. The BOP's method of calculation is set forth
in Program Statement 5880.28, which is part of its Sentencing
Computation Manual. Through a series of examples, the Program
Statement applies a formula which essentially multiplies the number
of days served by 0.148 (which is 54/365) for a prisoner who has
earned the maximum amount of GTC possible. This formula has the
effect of awarding a maximum of fifty-four days GCT for each full
year actually served, and a prorated amount of GCT for each portion
of a year actually served, based on a rate of fifty-four days of
GCT per 365 days in a year.1

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prisoner can receive a maximum of fifty-four days per year served,
any period served that is less than one year is prorated at a rate
of 54/365. This means that for each day served in year nine, the
prisoner has the potential to earn 0.148 (54/365) days GCT. Going
into year nine, the prisoner starts with only having to serve 298
days (365 - 67 days carried over from his GCT earned during years
one through eight) of year nine. Then, as the prisoner approaches
his projected release date, he is simultaneously earning the
possibility of additional GCT days. His total GCT for serving just
under eight and three-quarter years in prison is 470 days. That
equals fifty-four days for each of his eight full years served and
forty-eight days for his last portion of a year served.
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The BOP has also promulgated a rule, using the notice and
comment procedure of the Administrative Procedure Act, 5 U.S.C. §
553, which reflects its interpretation of "term of imprisonment" as
"time served" for purposes of calculating GCT. See 28 C.F.R. §
523.20. That rule states that "[p]ursuant to 18 U.S.C. § 3624(b),
. . . an inmate earns 54 days credit toward service of sentence
(good conduct time credit) for each year served." 28 C.F.R. §
523.20.
Thus, since both the Program Statement and 28 C.F.R.
§ 523.20 are premised on the BOP's interpretation of "term of
imprisonment" in § 3624(b)(1) to mean "time served," we must decide
whether it is permissible for the BOP to interpret "term of
imprisonment" to mean "time served" rather than "sentence imposed."
II. DISCUSSION
When we are asked to review an agency's construction of
a statute that it administers, we review that agency's
interpretation de novo, subject to established principles of

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deference, and begin with the language of the statute. See
Goldings v. Winn, 383 F.3d 17, 21 (1st Cir. 2004). The statute at
issue here, 18 U.S.C. § 3624(b)(1), provides that:
[A] prisoner who is serving a term of imprisonment
of more than 1 year[,] other than a term of
imprisonment for the duration of a prisoner's life,
may receive credit toward the service of the
prisoner's sentence, beyond the time served, of up
to 54 days at the end of each year of the
prisoner's term of imprisonment, beginning at the
end of the first year of the term, subject to
determination by the [BOP] that, during that year,
the prisoner has displayed exemplary compliance
with institutional disciplinary regulations. . . .
[C]redit for the last year or portion of a year of
the term of imprisonment shall be prorated and
credited within the last six weeks of the sentence.
Thus, at the end of each year, a prisoner's conduct is evaluated,
and if the prisoner has "displayed exemplary compliance with
institutional disciplinary regulations," the BOP may award the
prisoner credit of up to fifty-four days at the end of each year of
the prisoner's term of imprisonment. See 18 U.S.C. § 3624(b)(1).
A. Judicial Review of 18 U.S.C. § 3624(b)(1)
To evaluate the BOP's interpretation of "term of
imprisonment" as used in the GCT statute to mean "time served," we
look to the familiar two-part test enunciated in Chevron, U.S.A.,
Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837, 842-43
(1984). First, "employing traditional tools of statutory
construction, [we must] ascertain[] [whether] Congress had an
intention on the precise question at issue." Id. at 843 n.9. If
the answer to this inquiry is yes, then "that intention is the law

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and must be given effect." See id. If, however, "the statute is
silent or ambiguous with respect to the specific issue, the
question for the court is whether the agency's answer is based on
a permissible construction of the statute." Id. at 843.
(1) Language of the Statute
In step one of our Chevron analysis, we must ascertain
whether Congress has spoken on the precise question at issue. Id.,
467 U.S. at 843 n.9. We begin with the actual language of the
statute, and ask whether the phrase "term of imprisonment" has a
"plain and unambiguous meaning with regard to the particular
dispute in [this] case." See Duckworth v. Pratt & Whitney, Inc.,
152 F.3d 1, 5 (1st Cir. 1998) (quoting Robinson v. Shell Oil Co.,
519 U.S. 337, 340 (1997)). Because Congress has chosen not to
define the phrase "term of imprisonment" in the statute itself, we
can look to the dictionary for clarification of the plain meaning
of the words selected by Congress. See United States v. Lachman,
387 F.3d 42, 50 (1st Cir. 2004) ("Dictionaries of the English
language are a fundamental tool in ascertaining the plain meaning
of terms used in statutes and regulations."). Webster's Third New
International Dictionary (1996) defines "term" as "a limited or
definite extent of time: the time for which something lasts." It
defines "imprisonment" as "constraint of a person either by force
or by such other coercion as restrains him within limits against

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his will." The dictionary does little to resolve the ambiguity
posed here.
(2) Statute as a Whole
Having determined that the plain language of the statute,
standing alone, is ambiguous, we next ask whether this ambiguity
can be resolved by looking to the "specific context in which [the]
language is used, and the broader context of the statute as a
whole." Robinson, 519 U.S. at 341. Contrary to Perez-Olivo's
contention, and the now-reversed conclusion of the United States
District Court for the Western District of Wisconsin in White v.
Scibana, 314 F. Supp. 2d 834, 838-39 (W.D. Wis. 2004), rev'd, White
v. Scibana, No. 04-2410, 2004 WL 2749863 (7th Cir. Dec. 2, 2004),
the phrase "term of imprisonment" is used inconsistently throughout
18 U.S.C. § 3624. For example, in § 3624(a), "term of
imprisonment" plainly refers to the "sentence imposed." That
section states that each prisoner "shall be released by the [BOP]
on the date of the expiration of the prisoner's term of
imprisonment, less any time credited toward the service of the
prisoner's sentence." 18 U.S.C. § 3624(a). Plainly, if the BOP is
instructed to deduct time credited from the "term of imprisonment,"
then the "term of imprisonment" can only mean the "sentence
imposed." See 18 U.S.C. § 3624(a).
We compare the use of the phrase "term of imprisonment"
in § 3624(a) with the use of that same phrase in § 3624(d). In

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2 Some circuits have questioned the role of legislative
history in step one of a Chevron analysis. See, e.g., Coke v. Long
Island Care At Home, Ltd., 376 F.3d 118, 127 & n.3 (2d Cir. 2004)
(commenting that "the Supreme Court has issued mixed messages as to
whether a court may consider legislative history [in the first step
of a Chevron analysis]"); Am. Rivers v. Fed. Energy Regulatory
Comm'n, 201 F.3d 1186, 1196 & n.16 (9th Cir. 2000)
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§ 3624(d), the phrase "term of imprisonment" is plainly used to
mean "time served." That section states: "Upon the release of a
prisoner on the expiration of the prisoner's term of imprisonment,
the [BOP] shall furnish the prisoner with [suitable clothing, an
amount of money not to exceed $500, and transportation]." 18
U.S.C. § 3624(d). Plainly, Congress intended the prisoner be
furnished with these items upon release after completion of his
"time served." See 18 U.S.C. § 3624(d); see also Loeffler v.
Bureau of Prisons, No. 04-4627, 2004 WL 2417805, at *3 (S.D.N.Y.
Oct. 29, 2004) ("[I]t would make no sense to provide these
amenities at a time when the prisoner's original imposed sentence
had expired--a date that would obviously occur after the prisoner
had been released based on the good time credits.").
(3) Legislative History
After finding that the statute as a whole does not
resolve the ambiguity, we next check the legislative history of the
statute to confirm our conclusion. See Summit Inv. & Dev. Corp. v.
Leroux, 69 F.3d 608, 610 (1st Cir. 1995) ("[T]he congressional
intendment conveyed by unclear statutory language may be
discernible from its legislative history.").2

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("acknowledg[ing] the debate over the propriety, under Chevron, of
venturing beyond plain meaning analysis and resorting to
traditional implements of statutory construction to ascertain a
clear congressional directive"). First, we note that the Supreme
Court has recently again used legislative history to confirm the
plain meaning of language used in a statute in step one of its
Chevron analysis. See Gen. Dynamics Land Sys. v. Cline, 124 S. Ct.
1236, 1241-43 (2004). Second, in this case, we merely use the
legislative history to confirm that it does not resolve the
ambiguity in § 3624(b)(1), and therefore we need not reach the
issue of whether we would accept the legislative history as
conclusive evidence of Congress' intent to interpret "term of
imprisonment" if it were contrary to the BOP's interpretation.
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An earlier GCT statute, 18 U.S.C. § 4161 (repealed), was
in effect in various forms from 1902 until 1984, at which time
Congress codified the current GCT statute as part of the
Comprehensive Crime Control Act ("CCCA"). See Pub. L. No. 98-473,
98 Stat. 1976 (1984) (codified as amended in scattered sections of
18, 21, 28, 31, and 42 U.S.C.). The legislative history of the
repealed GCT statute reveals a clear congressional intent to
calculate GCT based on the "sentence imposed" rather than the "time
served." See, e.g., H. Rep. 86-935 (1959), reprinted in 1959
U.S.C.C.A.N. 2518, 2518-19 (discussing 1959 amendment to § 4161
intended in part to reverse a 1952 court decision interpreting the
statute as requiring GCT to be calculated based on time served
rather than sentence imposed). Contrary to Perez-Olivo's
contention, however, the legislative history of the GCT statute at
issue in this case does not indicate any congressional intent to
calculate GCT based on "time served" or "sentence imposed."

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An overarching purpose of the new GCT statute was to make
the "computation of credit toward early release pursuant to section
3624(b) [] considerably less complicated than under current law."
S. Rep. 98-224, at 146 (1984), reprinted in 1984 U.S.C.C.A.N. 3182,
3329. The "current law" at that time provided for, among other
things, a different rate of GCT depending on the length of the
prison term. See id. This goal of simplification in the new
statute was intended to serve two functions: to increase the
certainty of a prisoner's release date and to promote
administrative efficacy. See id. at 147, 1984 U.S.C.C.A.N. at
3330.
Perez-Olivo argues that this legislative intent to
simplify the computation of GCT supports his position that he
should earn fifty-four days per year for each year of his ten-year
sentence imposed--what could be easier than multiplying fifty-four
by ten? Perez-Olivo's position, however, does not account for the
proration language contained in the last sentence of § 3624(b)(1),
which states that "credit for the last year or portion of a year of
the term of imprisonment shall be prorated and credited within the
last six weeks of the sentence." 18 U.S.C. § 3624(b). In light of
this proration language, the BOP's method of calculation could not
be simpler: a prisoner earns fifty-four days per year for each
year served, and then the last portion of the year served is
prorated based on a rate of 54/365. Thus, it conforms with the

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legislative intent evidenced in the Senate Report that "[t]he
credit toward early release is earned at a steady and easily
determined rate that will have an obvious impact on the prisoner's
release date." See S. Rep. 98-224 at 147, 1984 U.S.C.C.A.N. at
3330.
Perez-Olivo proposes an alternative interpretation of the
proration language. He claims that it is included in the statute
simply because "not all sentences are for full years." According
to Perez-Olivo, if a prisoner is sentenced to one and one-half
years, the proration language is included in the statute to address
the "one-half year" portion of that sentence. Although we find
Perez-Olivo's reading of the proration language unpersuasive, it
does serve to confirm our original conclusion that "term of
imprisonment," as used in § 3624(b)(1), is ambiguous--an ambiguity
that cannot be resolved by looking to the legislative history of
the statute.
In further support of his position, Perez-Olivo points
to general statements regarding GCT made just after the passage of
the CCCA. See, e.g., 131 Cong. Rec. E37-02 (Jan. 3, 1985)
(Statement of Rep. Lee Hamilton introducing his Washington report
for Wed., Oct. 31, 1984, into the Cong. Rec., which states: "Now
sentences will be reduced only 15% for good behavior."). We find
that such statements do not evidence a clear congressional intent
to calculate GCT based on "sentence imposed," but instead can be

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3 Perez-Olivo also urges us to consider Senator Joseph Biden's
comments in the Congressional Record as legislative history
supporting his reading of the statute. See 141 Cong. Rec. S2348-
01, S2349 (Feb. 9, 1995) (statement of Sen. Biden). Senator Biden,
nearly twelve years after the passage of the CCCA, was quoted as
saying "I was the coauthor of [the CCCA]. In the Federal courts,
if a judge says you are going to go to prison for 10 years, you
know you are going to go to prison for at least 85 percent of that
time--8.5 years, which is what the law mandates. You can get up to
1.5 years in good time credits, but that is all. And we abolished
parole. So you know you'll be in prison for at least 8.5 years."
Id. We first question whether statements made almost twelve years
after the passage of an act can appropriately be used as
interpretive guides. See Goldings, 383 F.3d at 32 (noting that
"there is reason to heed the Supreme Court's frequent admonition
that using subsequent legislative history to interpret a statute is
a hazardous endeavor"). Second, as discussed above, Senator
Biden's references to "85 percent" and "8.5 years" can be construed
as mere shorthand for the calculation of GCT. See Loeffler, 2004
WL 2417805, at *5 n.1.
4 The Sixth Circuit has also upheld the BOP's method of
calculation in two unpublished opinions, Brown v. Hemingway, 53
Fed. Appx. 338 (6th Cir. 2002); Williams v. Lamanna, 20 Fed. Appx.
360 (6th Cir. 2001).
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read to indicate a "shorthand reference to the fact that the
statute permits a prisoner to receive GCT credit based on 15% of
the prisoner's time served (54 days divided by 365 days) rather
than a sub silentio interpretation of the meaning of 'term of
imprisonment.'" See Loeffler, 2004 WL 2417805, at *5 n.1. Thus,
the legislative history does not help resolve the ambiguity.3
(4) Other Jurisdictions
Lastly, we note that we are not alone in our conclusion
that § 3624(b)(1) is ambiguous. Almost every other court that has
visited this issue, including two other circuit courts of appeal,4
has found that "term of imprisonment" is ambiguous as used in §

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5 A notice of appeal was filed with the Second Circuit on June
21, 2004, and the parties are currently submitting briefs. See
Pasciuti v. Drew, No. 04-4039 (2d Cir.).
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3624(b)(1) and has upheld the BOP's interpretation of that term as
meaning "time served." White v. Scibana, No. 04-2410, 2004 WL
2749863, at *4 (7th Cir. Dec. 2, 2004); Pacheco-Camacho v. Hood,
272 F.3d 1266, 1271 (9th Cir. 2001); Moore v. Bureau of Prisons,
No. 04-5011, 2004 WL 2609589 (S.D.N.Y. Nov. 17, 2004); Young v.
Ashcroft, No. 04-1449, 2004 WL 2624724 (D. Or. Nov. 16, 2004); Sash
v. Zenk, No. 04-2476, 2004 WL 2549724 (E.D.N.Y Nov. 9, 2004);
Loeffler, 2004 WL 2417805, at *3; Graves v. Bledsoe, 334 F. Supp.
2d 906, 908 (W.D. Va. Aug. 19, 2004); Pasciuti v. Drew, No. 04-043,
2004 WL 1247813, at *4-5 (N.D.N.Y. June 2, 2004).5 The only court
that has found "term of imprisonment" to mean unambiguously
"sentence imposed" was recently reversed on appeal. See White v.
Scibana, No. 04-2410, 2004 WL 2749863 (7th Cir. Dec. 2, 2004)
(reversing White v. Scibana, 314 F. Supp. 2d 834 (W.D. Wisc.
2004)). We now join these other courts and conclude that the
phrase "term of imprisonment" as used in § 3634(b) is ambiguous,
and that this ambiguity cannot be resolved by looking at either the
context of the statute as a whole or the statute's legislative
history.
B. Review of the BOP's Interpretation of 18 U.S.C. § 3624(b)
Thus, having determined that § 3624(b)(1) is ambiguous,
we move to the second step in our Chevron analysis and ask whether

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the BOP's interpretation of the statute is a reasonable one. See
Bryson v. Shumway, 308 F.3d 79, 86-87 (1st Cir. 2002) ("If Congress
has not spoken on the precise question at issue, we respect the
statutory interpretation of the federal administrative agency given
that interpretative task, unless the interpretation is
unreasonable.").
(1) Delegation of Authority to Interpret § 3624(b)
As a preliminary matter, since there is no express
delegation of authority by Congress to the BOP in the statute to
interpret the phrase "term of imprisonment," we must ask whether
Congress has implicitly delegated this interpretative authority to
the BOP. See Pacheco-Camacho, 272 F.3d at 1270. We conclude that
it has.
We begin by noting that 5 U.S.C. § 301 provides for
executive agency rulemaking authority, and that the Attorney
General has expressly authorized the BOP "[to take final action in]
[a]pproving inmate disciplinary and good time regulations (18
U.S.C. § 3624)." 28 C.F.R. § 0.96(s). Moreover, under the GCT
statute, the BOP is charged with evaluating prisoner conduct to
determine whether a prisoner has earned GCT, and if so, how much.
The statute provides that the award of GCT is:
subject to determination by the Bureau of Prisons
that, during [the] year, the prisoner has displayed
exemplary compliance with institutional
disciplinary regulations. . . . [and] if the Bureau
determines that, during that year, the prisoner has
not satisfactorily complied with such institutional

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6 The BOP Program Statement would not likely be entitled to
full Chevron deference, but should be accorded some lesser degree
of deference under the Supreme Court's decisions in United States
v. Mead Corp., 533 U.S. 218, 230-31 (2001), and Skidmore v. Swift
& Co., 323 U.S. 134, 140 (1944). We need not, however, attempt to
discern the appropriate level of deference, because the BOP's
interpretation of the statute (calculating GCT based on "time-
served") is embodied in 28 C.F.R. § 523.20, which was adopted
pursuant to the notice-and-comment procedure of the Administrative
Procedure Act, see 62 Fed. Reg. 50,786 (Sept. 26, 1997). Thus, the
BOP policy of calculating GCT based on "time served" is entitled to
full deference under Chevron. See Bryson, 308 F.3d at 84; see also
White, 2004 WL 2749863, at *3; Pacheco-Comacho, 272 F.3d at 1268.
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regulations, the prisoner shall receive no such
credit toward services of the prisoner's sentence
or shall receive such lesser credit as the Bureau
determines to be appropriate.
18 U.S.C. § 3624(b)(1) (emphasis added).
The BOP is also charged with prorating GCT credit "for
the last year or portion of a year of the term of imprisonment."
Id. Therefore, the BOP must necessarily interpret "term of
imprisonment," either as "time served" or "sentence imposed," in
order to determine how much GCT can be awarded.
(2) Whether the BOP's Interpretation is Reasonable
Having determined that Congress has implicitly charged
the BOP with interpreting the ambiguous phrase "term of
imprisonment," we need only inquire whether the BOP's
interpretation is reasonable.6 See Chevron, 467 U.S. at 844. The
statute first directs the BOP that a prisoner "may receive credit
toward the service of the prisoner's sentence . . . at the end of
each year." 18 U.S.C. § 3624(b)(1). This is a clear congressional

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directive that the BOP look retroactively at a prisoner's conduct
over the prior year, which makes it reasonable for the BOP only to
award GCT for time served.
Second, the statute goes on to direct the BOP that a
prisoner only may receive GCT "[if] the prisoner has displayed
exemplary compliance with institutional disciplinary regulations."
18 U.S.C. § 3624(b)(1). This evidences Congress' clear intent that
the BOP evaluate a prisoner's conduct during his time in prison,
making it reasonable for the BOP to require that time actually be
served in order for the conduct during that time to be evaluated.
Lastly, the statute provides that "credit for the last
year or portion of a year of the term of imprisonment shall be
prorated." 18 U.S.C. § 3624(b)(1). We find it reasonable for the
BOP to read this proration language in conjunction with the "54
days at the end of each year" language to allow a prisoner to earn
a maximum of fifty-four days for each full year served, and then to
earn a prorated amount of GCT for the last portion of a year
served, at a rate of 54/365 GCT days per year.
(3) Rule of Lenity
Perez-Olivo argues, however, that we should not give
deference under Chevron to the BOP's interpretation of the GCT
statute. He argues instead that we should apply the rule of
lenity. We disagree. The rule of lenity provides that "where
there is ambiguity in a criminal statute, doubts are resolved in

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favor of the defendant." United States v. Bass, 404 U.S. 336, 348
(1971). Here, we are evaluating the reasonableness of the BOP's
calculation of reductions in a sentence for GCT, which is not,
strictly speaking, a "criminal" statute, and thus we do not believe
the rule of lenity would apply. This determination, however, is
unnecessary, because even if we were to assume, arguendo, that the
GCT statute was "criminal," we note that "[t]he rule of lenity
applies only if, after seizing everything from which aid can be
derived, we can make no more than a guess as to what Congress
intended." Reno v. Koray, 515 U.S. 50, 65 (1995) (citations and
internal quotation marks omitted). Furthermore, the rule of lenity
does not foreclose deference to an administrative agency's
reasonable interpretation of a statute. See Babbitt v. Sweet Home
Chapter of Communities, 515 U.S. 687, 704 n.18 (1995) ("We have
never suggested that the rule of lenity should provide the standard
for reviewing facial challenges to administrative regulations
whenever the governing statute authorizes criminal enforcement.").
Thus, because we find that the BOP's method of calculating GCT
based on "time served" is reasonable under § 3624(b), it would be
unnecessary to resort to the rule of lenity even if it were to
apply to the GCT statute.

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III. CONCLUSION
For the reasons set forth above, the denial of Perez-
Olivo's petition for a Writ of Habeas Corpus under 18 U.S.C. §
2241 is AFFIRMED.

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