Sabil Mujahid appeals the denial of his 28 U.S.C. § 2241 petition for a writ of habeas corpus, challenging the Bureau of Prisons’ (“BOP” or “Bureau”) interpretation of the maximum good time credit a federal prisoner can receive under 18 U.S.C. § 3624(b). Mujahid asserts that the Bureau’s interpretation, which allows a prisoner serving a ten-year sentence to earn a maximum of 470 days credit, contradicts the statute’s stated allowance of 54 days of credit per year. We affirm.

I

The facts relevant to this appeal are not in dispute. In 1995, the United States District Court for the District of Alaska sentenced Mujahid to ten years imprisonment, plus three years supervised release, upon his conviction under 18 U.S.C. § 922(g)(1) (felon in possession of a firearm). He began his term in custody on March 21 of that year.

In 2002, while incarcerated at the Federal Correctional Institution in Sheridan, Oregon (“FCI-Sheridan”), Mujahid filed this challenge to the Bureau’s interpretation of the good time statute. Mujahid’s petition, which he filed in the District of Oregon, named as respondent the warden at FCI-Sheridan. The magistrate judge reviewing the petition disagreed with the assertion that the Bureau’s interpretation deprived Mujahid of good time credit. The district court adopted the magistrate judge’s Findings and Recommendations (with one modification not relevant here) and denied Mujahid’s petition on November 4, 2003. Mujahid timely appealed.

The government represents that Muja-hid began his three-year term of supervised release on January 6, 2004. ^[1]

II

As an initial matter, we determine whether events subsequent to the district court’s denial of Mujahid’s petition deprive this court of jurisdiction or render this appeal moot. The government contends that Mujahid’s placement onto supervised release prevents us from providing any relief. We disagree.

A

The government’s first contention, marginally raised in its briefing and argued at length during oral argument, is that we lack jurisdiction over this appeal because Mujahid is no longer imprisoned by the named respondent-warden. ^[2] Established[*994] principles of habeas procedure suggest otherwise.

When Mujahid filed his petition, he was incarcerated in Oregon. He filed his petition in district court, in the District of Oregon. He named as respondent the warden of the institution where he was imprisoned. These steps properly complied with habeas procedure. See Rumsfeld v. Padilla, 542 U.S. 426, 124 S.Ct. 2711, 2720, 159 L.Ed.2d 513 (2004). Mujahid’s subsequent transfer and placement onto supervised release do not alter this analysis. As the government recognizes, a habeas petitioner remains in the custody of the United States while on supervised release. Matus-Leva v. United States, 287 F.3d 758, 761 (9th Cir.2002). And as we stated in Francis v. Rison, 894 F.2d 353, 354 (9th Cir.1990) (internal quotation marks and citations omitted), “jurisdiction attaches on the initial filing for habeas corpus relief, and it is not destroyed by a transfer of the petitioner and the accompanying custodial change.”

B

The next government challenge asserts mootness. “The burden of demonstrating mootness is a heavy one.” Cantrell v. City of Long Beach, 241 F.3d 674, 678 (9th Cir.2001). The government has not met that burden.

An appeal is moot “when, by virtue of an intervening event, a court of appeals cannot grant any effectual relief whatever in favor of the appellant.” Calderon v. Moore, 518 U.S. 149, 150, 116 S.Ct. 2066, 135 L.Ed.2d 453 (1996) (per curiam) (citation and internal quotation marks omitted). Failure to satisfy Article Ill’s case-or-controversy requirement renders a habeas petition moot. Spencer v. Kemna, 523 U.S. 1, 7, 118 S.Ct. 978, 140 L.Ed.2d 43 (1998). “This means that, throughout the litigation, the plaintiff must have suffered, or be threatened with, an actual injury traceable to the defendant and likely to be redressed by a favorable judicial decision.” Id. (citation and internal quotation marks omitted).

The government argues that we are unable to provide any relief to Mujahid because he completed his term of imprisonment and was placed on supervised release. The government relies on United States v. Johnson, 529 U.S. 53, 54, 120 S.Ct. 1114, 146 L.Ed.2d 39 (2000), to support its position. We agree that Johnson holds that a prisoner who wrongfully serves excess prison time is not entitled to an automatic reduction in his term of supervised release. Id. at 60, 120 S.Ct. 1114. But our post-Johnson precedent does not support construing Johnson in the manner advocated by the government.

We addressed this very issue in Gunderson v. Hood, 268 F.3d 1149, 1153 (9th Cir.2001). Although the petitioner in Gunderson challenged an agency practice affecting the length of his sentence, we recognized that the court was unable to order any reduction in prison time because he would not be eligible for such relief until his term of imprisonment expired. We held this fact did not render the petition moot, however, because the petition[*995] er’s sentence included a term of supervised release. The “possibility” that the sentencing court would use its discretion to reduce a term of supervised release under 18 U.S.C. § 3583(e)(2) was enough to prevent the petition from being moot. Id.; see also United States v. Verdin, 243 F.3d 1174, 1178 (9th Cir.2001) (holding a defendant on supervised release retained a personal stake in the appeal of his sentence because, if he prevailed, “he could be re-sentenced to a shorter period of supervised release”).

Gtunderson controls our mootness inquiry. There “is a possibility” that Mujahid could receive a reduction in his term of supervised release under 18 U.S.C. § 3583(e)(2). 253 F.3d at 1153. Gunderson does not require more.

The government’s attempt to distinguish Gunderson is unavailing. The government maintains that the Gunderson petitioner, unlike Mujahid, sought habeas relief in the same court in which he was originally sentenced. This supposed fact allegedly differentiates Gunderson because Mujahid’s habeas court (in the District of Oregon) has no control over the decision to modify the supervised release terms, which rest with the sentencing court (in the District of Alaska).

We cannot accept this argument. Gun-derson, like Mujahid, followed general ha-beas procedure in naming as respondent the warden of the prison where he was incarcerated at the time of filing his petition. Gunderson, 268 F.3d at 1152-53; see also Padilla, 124 S.Ct. at 2720. The Gunderson opinion does not state that the petitioner was seeking habeas relief before the same court in which he was sentenced, and there is no indication that its mootness analysis turned on such a fortuitous occurrence. ^[3]

C

Mujahid filed his habeas petition in the proper district court, naming the proper respondent. See Padilla, 124 S.Ct. at 2718. He remains in “custody” for habeas purposes. Matus-Leva, 287 F.3d at 761. His petition asserts an injury due to the duration of his sentence and seeks relief through a possible reduction of his term in custody. Gunderson, 268 F.3d at 1153. This appeal is properly before us and is not moot.

Ill

We now turn to the merits of Mujahid’s challenge to the BOP’s interpretation of the federal good time statute, 18 U.S.C. § 3624(b). Mujahid asserts that the BOP’s interpretation erroneously reduces the amount of good time credit available on a ten-year sentence from 540 to 470 days. Although Mujahid’s reading of the statute is arguably plausible, we have previously held that the BOP’s contrary interpretation is reasonable and subject to deference. Pacheco-Camacho v. Hood, 272 F.3d 1266, 1270 (9th Cir.2001). This determination is controlling.

A

[*996] At issue in this appeal is the 1995 ^[4] version of 18 U.S.C. § 3624(b)(1), which states in relevant part (emphasis added):

(b) Credit toward service of sentence for satisfactory behavior.—

(1) A prisoner ... who is serving a term of imprisonment of more than one year, other than a term of imprisonment for the duration of the prisoner’s life, shall receive credit toward the service of the prisoner’s sentence, beyond the time served, of fifty-four 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, unless the Bureau of Prisons determines that, during that year, the prisoner has not satisfactorily complied with ... institutional disciplinary regulations.... The Bureau’s determination [of satisfactory compliance] shall be made within fifteen days after the end of each year of the sentence. Credit that has not been earned may not later be granted. 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.

The Bureau and Mujahid disagree on whether “term of imprisonment” as used in the italicized portion of the statute means time actually served (BOP interpretation) or sentence imposed (Mujahid interpretation). The BOP implementing regulation provides:

Pursuant to 18 U.S.C. 3624(b), as in effect for offenses committed on or after November 1, 1987 but before April 26, 1996, an inmate earns 54 days credit toward service of sentence (good conduct time credit) for each year served. This amount is prorated when the time served by the inmate for the sentence during the year is less than a full year.

28 C.F.R. § 523.20 (emphasis added). ^[5]

In accordance with this regulation and the Bureau’s applicable Program Statement, a prisoner does not “earn” good time credit until after serving that time. See Federal Bureau of Prisons Program Statement 5880.28 (Feb. 21, 1992). To earn 54 days of credit, a prisoner must first complete 365 days of incarceration. The BOP prorates awards during the last year that a prisoner is incarcerated, awarding 0.148 days credit [54/365 = 0.148] per day actually served that year. See Pacheco-Camacho, 272 F.3d at 1267-1268.

Under these calculations, Mujahid accumulated 432 days of credit over eight years [ (54 days/year) x (8 years) = 432]. Because Mujahid had enough credit to qualify for release during his ninth year in prison, the BOP prorated the amount of credit he could earn that partial year, awarding 38 days. Mujahid received no credit for the tenth year of his sentence, when he was not in prison.

Mujahid, in contrast, reads this statute as awarding good time credit based on the sentence imposed. Using the straight-forward calculation of 54 days per year multiplied by ten years, Mujahid argues that he was entitled to 540 days of credit. To avoid awarding credit for time not served, Mujahid essentially starts counting toward the next “year” of imprisonment every 311 days. ^[6]

[*997] The end result is that, over a ten-year sentence, Mujahid’s interpretation enables a prisoner to earn 70 more days of credit than allowed by the BOP.

B

This dispute turns on whether we accept the BOP’s interpretation of the phrase “term of imprisonment” to mean “time served.” “Because this case involves an administrative agency’s construction of a statute that it administers, our analysis is governed by Chevron U.S.A. Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984).” Food and Drug Admin. v. Brown & Williamson Tobacco Corp., 529 U.S. 120, 132, 120 S.Ct. 1291, 146 L.Ed.2d 121 (2000); accord Pacheco-Camacho, 272 F.3d at 1268. Under the Chevron framework, a reviewing court first determines if “ ‘Congress has directly spoken to the precise question at issue,’ in such a way that ‘the intent of Congress is clear.’ ” Pacheco-Camacho, 272 F.3d at 1268 (quoting Chevron, 467 U.S. at 842, 104 S.Ct. 2778). If the statute is silent or ambiguous, the court decides “whether the agency’s interpretation ‘is based on a permissible construction of the statute.’ ” Id. (quoting Chevron, 467 U.S. at 843, 104 S.Ct. 2778).

In Pacheco-Camacho, we held that the BOP’s interpretation of 18 U.S.C. § 3624(b) is entitled to full Chevron deference. At issue in Pacheco-Camacho was the BOP’s policy for prorating the good time credit of a prisoner sentenced to one year plus a day imprisonment. We first determined that the phrase “term of imprisonment” as used in § 3624(b) is ambiguous, observing that to read “term of imprisonment” as “sentence imposed” would be inconsistent with a statute that contemplates prorating credit for the last year of imprisonment. Id. at 1268. We also concluded that the Bureau’s interpretation was supported by legislative history indicating an attempt to “strike a balance between simplicity and fairness” by calculating credits in a consistent manner and prorating credits to ensure that those who served more time were eligible for more credit. Id. at 1270. We relied on these same reasons to hold that the BOP’s interpretation of “term of imprisonment” as “time served” was reasonable. Id. at 1271.

Mujahid’s interpretation of § 3624(b) is at odds with Pacheco-Camacho’s holding that the BOP’s interpretation is reasonable and subject to deference. We are bound by Pacheco-Camacho’s holding unless (1) the issue presented here is sufficiently distinguishable or (2) binding authority casts sufficient doubt on the validity of Pacheco-Camacho’s analysis to allow us to disregard its reasoning. We are unconvinced on both fronts.

1

Mujahid’s attempts to distinguish Pacheco-Camacho are unpersuasive. Mujahid would limit Pacheco-Camacho to solely addressing the meaning of “term of imprisonment” as it relates to prorating credits during the last year of a prisoner’s sentence. He asserts that his petition differs because he challenges the BOP’s calculation of good time credits overall. But so did Pacheco-Camacho. In fact, Pacheco-Camacho made the same argument and used the same provision for support. Like Mujahid, Pacheco-Camacho argued that “when the statute awards fifty-four days ‘at the end of each year of the prisoner’s[*998] term of imprisonment,’ this award should be based on the sentence imposed, without regard to the time actually served.” Id. at 1268. Our rejection of Pacheco-Camacho’s position indicates that our holding was not as limited as Mujahid contends.

Mujahid’s assertion that Pacheco-Camacho controls the meaning of “term of imprisonment” only in the context of prorating credit is problematic for another reason as well. Under even this most narrow reading of Pacheco-Camacho, that decision still holds that the BOP’s interpretation of “term of imprisonment” in the last sentence of § 3624 as “time served” is reasonable. See id. at 1270-71. Mujahid does not explain how, given' this precedent, interpreting “term of imprisonment” differently (i.e., as “sentence imposed”) earlier in the same statute is any more consistent with rules of intra-statutory interpretation than the interpretation given by the Bureau.

2

Besides attempting to limit the reach of Pacheco-Camacho, Mujahid argues that subsequent Supreme Court cases have undermined Pacheco-Camacho’s “mode of reasoning.” Mujahid asserts that recent cases suggest that Pacheco-Camacho erred in not applying the rule of lenity before applying Chevron deference. For one three-judge panel to disregard prior binding authority, “the relevant court of last resort must have undercut the theory or reasoning underlying the prior circuit precedent in such a way that the cases are clearly irreconcilable.” Miller v. Gammie, 335 F.3d 889, 900 (9th Cir.2003). Mujahid has not persuaded us that we are faced with such a situation here. ^[7]

Pacheco-Camacho holds that the rule of lenity “does not prevent an agency from resolving statutory ambiguity through a valid regulation.” 272 F.3d at 1271. We cited Supreme Court precedent for support. See Babbitt v. Sweet Home Chapter of Cmtys. for a Great Oregon, 515 U.S. 687, 704 n. 18, 115 S.Ct. 2407, 132 L.Ed.2d 597 (1995) (“We have never suggested that the rule of lenity should provide the standard for reviewing facial challenges to administrative regúlations whenever the governing statute authorizes criminal enforcement.”). We explained that our decir sion comported with the rule’s purpose as well. Specifically, the rule of lenity is designed to “ensureí ] that the penal laws will be sufficiently clear, so that individuals do not accidentally run afoul of them and courts do not impose prohibitions greater than the legislature intended.” Pacheco-Camacho, 272 F.3d at 1271. Regulations such as the one at issue here “gives the public sufficient warning to ensure that nobody mistakes the ambit of the law or its penalties.” Id. at 1272. We also noted that the Supreme Court has applied Chevron deference in construing another BOP-administered statute affecting prison terms. See id. (citing Lopez v. Davis, 531 U.S. 230, 242, 121 S.Ct. 714, 148 L.Ed.2d 635 (2001)).

We cannot say that binding authority has “undercut” this analysis. By collecting assorted passages from recent Supreme Court opinions, Mujahid creates an argument that is tenuous at best and requires us to fill in more blanks than we are willing to do. In particular, neither Leocal [*999] v. Ashcroft, — U.S. —, 125 S.Ct. 377, 160 L.Ed.2d 271 (2004), nor Clark v. Martinez, — U.S. —, 125 S.Ct. 716, 160 L.Ed.2d 734 (2005), address the relationship of Chevron deference to the rule of lenity. Rather, both cases reference the rule of lenity in dicta concerning unrelated points. See Leocal, 125 S.Ct. at 384 n. 8 (stating that “consistency” requires applying the rule of lenity to a statute that has both criminal and noncriminal applications); Clark, 125 S.Ct. at 724 (citing the reference to the rule of lenity in Leocal and United States v. Thompson/Center Arms Co., 504 U.S. 505, 517-18 and n. 10, 112 S.Ct. 2102, 119 L.Ed.2d 308 (1992) (plurality opinion), in stating that the “lowest common denominator” governs when construing statutory language with more than one application).

The language cited in these cases supports that the rule of lenity can play an important role in statutory construction; it does not address when the rule of lenity takes priority over Chevron deference. And, ultimately, it is the answer to this question that Mujahid must convince us has been provided, or most assuredly would be provided, by the Supreme Court in a manner “irreconcilable” with Pacheco-Camacho. The cases relied on by Mujahid do not do so.

IV

Pacheco-Camacho established that the phrase “term of imprisonment” in 18 U.S.C. § 3624(b)(1) is ambiguous, that the BOP’s interpretation was reasonable, and is thus entitled to deference. Mujahid’s position rests on an interpretation of this statute at odds with binding authority of this court. ^[8]

AFFIRMED.