OPINION
WILKINSON, Circuit Judge:Brett Marvin Randall, a federal inmate, asserts that he is entitled to credit against his prison sentence for time that he spent in a drug rehabilitation center prior to entering a federal penitentiary. He points to 18 U.S.C. § 3568, which governs calculation of terms of imprisonment, as the source of his claimed right. We conclude that Randall is not entitled to credit under that statute and therefore affirm the district court’s judgment.
I.
Randall was arrested on January 13, 1986 on the charge of robbing a bank in Baltimore, Maryland. At his bail hearing on January 15, Randall informed the court that he required treatment for a severe drug addiction. He requested that, pending trial, he be allowed to enter Second Genesis, an intensive residential rehabilitation and counseling center in Baltimore. Randall had applied for admission to the center a few weeks before his arrest. The court released Randall on a partially-secured bond and entered an order placing him in the custody of the Pretrial Services Agency. Under the terms of the order, Randall was confined to the premises of Second Genesis at all times except for required court appearances and meetings with counsel.
Randall entered into a plea agreement with the government and pled guilty on May 2 to one count of bank robbery in violation of 18 U.S.C. § 2113. Sentencing was deferred at the government’s request in order to allow Randall to complete his obligations under the agreement. After a few months, Randall asked to be sentenced and a hearing was set for July 31. The district court imposed a twelve year sentence. At that time, Randall requested that the court delay the date on which he was to report to prison so that he could complete the program at Second Genesis. Although Randall initially sought a reporting date of January 1, 1987, the court set a date of October 1, 1986. By that time, the court reasoned, Randall would have completed further treatment at Second Genesis and would have had the opportunity to cooperate further with the government by testifying at a confederate’s upcoming trial.
As ordered, Randall returned to Second Genesis and then reported to prison on October 1, 1986. A few years later, he sought credit towards service of his sentence pursuant to 18 U.S.C. § 3568 for the 257 days he resided at Second Genesis. *524The Bureau of Prisons (BOP) denied his requests, citing its policy that time spent in a residential community center is not credited towards a term of imprisonment. Randall then filed a petition for a writ of habeas corpus with the United States District Court for the Eastern District of Virginia. The district court dismissed the petition on the basis of this court’s recent decision in United States v. Insley, 927 F.2d 185 (4th Cir.1991).
Randall now appeals.
II.
At issue here is the interpretation of 18 U.S.C. § 3568. That section provides that the “Attorney General shall give any [person convicted of an offense] credit toward service of his sentence for any days spent in custody in connection with the offense or acts for which sentence was imposed.” Randall argues that he was clearly confined by judicial order to Second Genesis under restrictive conditions and was placed in the custody of the Pretrial Services Agency. He claims he is therefore entitled to credit toward his sentence under the plain language of the statute.
Despite Randall’s protestations, we do not believe that “custody” as used in § 3568 has the meaning he would ascribe to it. The district court properly viewed our recent decision in United States v. Insley, 927 F.2d 185 (4th Cir.1991) as directing dismissal of this claim. In Insley, the defendant had been released on appeal bond subject to certain conditions following her conviction on drug charges. In holding that she had not been “officially detained” under 18 U.S.C. § 3585(b),1 we stated plainly that “[e]onditions of release are not custody.” Id. at 186. We rejected Insley’s efforts to establish a broad definition of “official detention” and declared that we did “not adopt the approach of those courts which have granted credit for time spent out of jail.” Id. at 187. Here, Randall had not been incarcerated in jail but instead had been released on conditional bond into a residential treatment center. Our decision in Insley thus speaks directly to Randall’s attempts to broaden the reach of § 3568. See also United States v. Woods, 888 F.2d 653, 655 (10th Cir.1989) (no credit against sentence for time spent in halfway house); United States v. Smith, 869 F.2d 835, 837 (5th Cir.1989) (same).2
Randall attempts to avoid Insley by arguing that the decision did not actually establish a bright line rule but rather turned on the relative lack of severity of the restrictions imposed on Insley. He asks this court to consider the regulations and physical constraints prescribed at Second Genesis as well as the conditions of the court’s order and to conclude that they *525were sufficiently restrictive to justify an award of credit toward his sentence. To bolster his assertions, Randall points to a Program Statement promulgated by the Bureau of Prisons (BOP), which he claims identifies the degree of restraint as the critical factor in determining credit due under 18 U.S.C. § 3568.
Randall’s arguments are unavailing, however. We have already discussed the decision in Insley. Nor does Randall gain any support from the BOP, which relied upon its established policy in denying Randall credit for his time at Second Genesis. BOP Program Statement 5880.24(5) defines “in custody” for purposes of awarding credit towards a sentence as “physical incarceration in a jail-type institution or facility.” (emphasis omitted). The BOP Statement also directly addresses Randall’s circumstances:
Time spent in residence in a residential community center ... as a condition of bail or bond, including the “Pretrial Services” program (18 USC 3152-3154), is not creditable as jail time since the degree of restraint provided by residence in a community center is not sufficient restraint to constitute custody within the meaning or intent of 18 USC 3568.
Id. at (5)(b)(5) (emphasis omitted). This particular policy statement represents “a reasonable opinion by officials having greater knowledge of federal penal policy than we judges have, so we are inclined to defer to it.” Ramsey v. Brennan, 878 F.2d 995, 996 (7th Cir.1989) (denying credit for time spent in halfway house).3
Randall nevertheless contends that the “degree of restraint” to which he was subjected at his residential center was sufficient to constitute “custody.” His argument reveals a misunderstanding of the relevant terms. There exists a strong presumption that “custody” refers to the legal authority of the custodian rather than to actual housing conditions. The physical conditions to which federal inmates are subjected vary widely, from maximum security prisons and isolation cells to work release programs. The only common link among all those settings is that the inmates are always subject to the authority of the Attorney General. That single factor encompasses a wide variety of restrictions. For example, federal inmates are governed by the BOP’s disciplinary procedures, their site and conditions of incarceration can be changed at the discretion of the Attorney General, they are subject to immediate arrest and return as well as prosecution under 18 U.S.C. § 751(a) if they escape their place of confinement, and they can be restrained by potentially lethal force.
By contrast, release on bond includes none of these restrictions. Randall was placed in Second Genesis by order of the court and was answerable to the court rather than to the Attorney General. Had Randall violated the conditions of his release, he would not have been subject to immediate arrest; the government would have had to move for revocation of the order of release and for issuance of an arrest warrant. See 18 U.S.C. § 3148(b). The staff at Second Genesis had no legal authority to prevent Randall from leaving and certainly could pose no threat of lethal force to prevent him from doing so. Significant differences in restraints thus pertain, depending upon the authority of the custodian. See Moreland v. United States, 932 F.2d 690, 695 (8th Cir.1991) (Magill, J., dissenting). Randall would have us ignore the fact that he is seeking credit for time that he did not spend in the custody of the Attorney General.
Additionally, Randall’s proposed interpretation of custody would mire the judiciary in a swamp of factual and circumstantial details that would likely produce inconsistent and standardless decisions. The pro*526grams and rules of residential treatment centers vary dramatically with each institution. Every prisoner who had spent time in such a center would argue that his particular release restrictions rose to a level requiring credit towards his sentence. Courts are ill-suited to compare the myriad combinations of restrictions and fashion a coherent scheme of awarding credit. No obvious rule informs us how to weight a midnight curfew against one beginning at eight in the evening, or a five-day-a-week regime against one lasting seven days. Such policy judgments are better left to the Bureau of Prisons and the Attorney General. So long as their judgments comport with the relevant statutes, we are constrained to uphold them.
Randall should not be heard to complain that this result is unfair. The BOP’s policy was longstanding and should have placed him on notice that credit would not be granted for time spent outside jail. The sentencing court also provided notice by informing Randall, “I am putting you out into Second Genesis until you surrender into federal custody on October First.” (emphasis added). Also, Randall had already applied for admission to Second Genesis before he committed the crime for which he was arrested. The court allowed him to continue with his plans and to receive the benefit of treatment, all at Randall’s own request. Moreover, Second Genesis does not allow any of its residents to leave the house during the first four to six months of treatment unless they are accompanied by an authorized person. Thus the conditions by which Randall abid-ed were only marginally more restrictive than those applied to the other residents. Under such circumstances, Randall’s arguments that he is entitled to credit under 18 U.S.C. § 3568 are even less persuasive.
III.
For all of the foregoing reasons, the judgment of the district court is
AFFIRMED.
. Section 3568 applies to offenses committed before November 1, 1987. Section 3585 is the successor statute. The new provision refers to “official detention” rather than to "custody," but as we noted in Insley, nothing in its legislative history indicates a departure from the precedent decided under Section 3568. 927 F.2d at 186.
. Another paragraph of § 3568 provides credit to a convicted person for time spent "committed to a jail or other place of detention to await transportation to the place at which his sentence is to be served.”
We cannot agree with the dissent that this provision covers Randall’s situation. In the first place, our review of the record reveals that it was Randall who initiated the request following sentencing for continued placement at Second Genesis, and his asserted reason was to complete his treatment. The government stood silent on the point and it was Randall who used the upcoming trial to argue for a delayed turn-in date. Second, Randall’s situation is no different from that of the defendant in Insley, who had been sentenced and then conditionally released on bond pending appeal, and who received no credit for time spent before reporting to prison. Third, Randall was released pursuant to 18 U.S.C. § 3143(a) as someone "waiting imposition or execution of sentence.” (emphasis added). It was the court, and not the Attorney General, that set Randall’s conditions of release. The court made clear at the sentencing hearing that Randall was to remain at Second Genesis under the authority of the court until he entered "into federal custody on October 1st.” Failure to comply with the order would have resulted in a contempt of court citation or a forfeiture of bond.
Finally, we believe the paradigm situation to which the "awaiting transportation” language of § 3568 applies is that of someone who reports to the United States Marshal at a specified date and is then temporarily held awaiting permanent placement within the federal prison system. In all events, it is difficult to stretch the statutory term "awaiting transportation" to encompass a period of two months spent in a drug treatment center at Randall’s own request.
. Randall also argues that denial of credit for time spent in residential centers will discourage those in his situation from seeking treatment for their addictions. The government counters that if Randall’s position were adopted then rehabilitation programs would become havens for those seeking credit on their sentences rather than resources for those undertaking a genuine effort at self-betterment. Where the competing policies touch so profoundly upon the nature and purposes of sentencing, we think they are not for the judiciary in the first instance to resolve. The Attorney General, acting through the Bureau of Prisons, has advanced a view consistent with the statute to which deference is warranted in the absence of any clear expression from Congress. See Ramsey, 878 F.2d at 996.