This case concerns the calculation of credit for presentence time spent in custody. Petitioning for a writ of habeas corpus, Roland Shelvy claimed that he should receive, in addition to the 233 days of credit allowed by the District of Columbia Department of Corrections, a further credit' of approximately six months. The district court denied Shelvy’s application; it held that the statute governing presentence credit, 18 U.S.C. § 3568, does not permit the relief Shelvy seeks.1 We affirm the district court’s judgment. Our holding rests on two interrelated conclusions. Both grounds of decision stem from a principal objective of Congress in enacting 18 U.S.C. § 3568: to “remove confusion,” “produce certainty,” and “prevent juggling” as to the date on which a sentence commences. See S.Rep. No. 803, 72d Cong., 1st Sess. 2 (1932); H.R. Rep. No. 960, 72d Cong., 1st Sess. 2 (1932).
First, we conclude that credit for presentence time spent in custody against one or more eventual sentences continues until a defendant commences service of a sentence; but once a defendant actually commences service of a sentence, presentence credit ceases. Upon the prisoner’s reception at the institution for service of that sentence, or commitment to a place of detention to await transportation to the place at which the sentence shall be served, other pending charges do not extend the prisoner’s eligibility for credit for time spent in custody prior to the imposition of a sentence. Second, we conclude that a second sentence ordered to run concurrently with a sentence earlier imposed runs with the remainder of the earlier sentence.
I.
Shelvy was charged, held in presentence custody, and eventually sentenced in two separate proceedings. He was arrested on September 24, 1969, on charges of armed robbery, robbery, and two counts of assault with a dangerous weapon (case 1). He alleges that on the same day, he was also arrested and charged with murder (case 2).2 Shelvy has remained incarcerated since his arrest.
*443Case 1 was tried before a jury on March 11, 1970. Shelvy was found guilty on three counts. On May 15,1970, he was sentenced to imprisonment for six to eighteen years for armed robbery, and two to six years on each of the assault counts. These sentences were ordered to run concurrently.
In case 2, Shelvy entered a plea of guilty to second degree murder on October 13, 1970. On November 20, 1970, he was sentenced to the maximum term authorized for this offense, imprisonment for fifteen years to life.3 The district judge ordered the sentence to run concurrently with any sentence then being served.
Shelvy has received credit against both sentences for the period between September 24,1969, the date of his arrest, and May 15, 1970, the date he was sentenced in case 1. Despite commencement of the case 1 sentence on the latter date, Shelvy claims he is entitled to presentence credit in case 2 for the period from May 15, 1970, until November 20, 1970, the date on which the case 2 sentence commenced. In effect, he urges that we hold both sentencing dates irrelevant, and direct that he receive credit against the longer sentence — the one in case 2 — for every day he has been incarcerated since his arrest on September 24, 1969.
II.
The statute controlling credit for time spent in custody prior to the imposition of sentence provides, in relevant part:
The sentence of imprisonment of any person convicted of an offense shall commence to run from the date on which such person is received at the penitentiary, reformatory, or jail for service of such sentence. The Attorney General shall give any such person credit toward service of his sentence for any days spent in custody in connection with the offense or acts for which sentence was imposed....
No sentence shall prescribe any other method of computing the term.
18 U.S.C. § 3568 (emphasis added). The district court held that the underscored language foreclosed Shelvy’s claim:
[F]rom May 15[, 1970,] on, the petitioner was incarcerated pursuant to his sentence in case 1; this being so, [he] was not spending [that time] in custody “in connection with the offense in [case 2]” and, hence, he is not entitled to credit for this time served.
Shelvy v. Whitfield, No. 82-1555, slip op. at 2 (D.D.C. July 30, 1982).
We recognize the force of the district court’s position. However, Shelvy’s case has an anomalous aspect: If the two sentence dates had been interchanged — the case 2 (murder) sentence imposed on May 15, 1970, the case 1 (robbery) sentence on November 20, 1970 — it appears that Shelvy would have been entitled to the six months credit he seeks. He would have received credit for presentence custody up to May 15, 1970, and for service of the case 2 sentence thereafter. In this hypothetical situation, there would have been no need to answer the question whether credit should have accrued against the case 1 sentence during the period May 15, 1970, to November 20,1970, for the absence of credit would have had no effect on the total period of incarceration; the case 1 sentence, six to eighteen years, even with no credit gained from May 15,1970, to November 20,1970, if ordered to run concurrently with the case 2 sentence, would have fit entirely within the latter, fifteen years to life, sentence.
Shelvy appeared pro se in the district court and on appeal. Because we believed he might have an arguable point, we invited *444the Public Defender Service to assist the court by submitting a brief, amicus curiae. That brief cogently points out that because Shelvy’s sentence in case 1 is totally subsumed within the considerably longer, concurrently running sentence in case 2, credit against the case 1 sentence, for all practical purposes, is meaningless. Credit against that sentence alone cannot shorten the time Shelvy will spend in prison.
III.
We are impelled to agree with the district court that Shelvy is not entitled to any additional “credit for time [he spent] in custody prior to the imposition of sentence.” See 18 U.S.C. § 3568 (caption) (emphasis added). First, the section in question fixes the time when a sentence commences. Beyond debate, Shelvy commenced serving a sentence on May 15, 1970. Next, the section provides for presentence credit. Congress has consistently described this provision as aimed at credit for confinement before and during trial, and not at credit for any post-sentence custody. See S.Rep. No. 750, 89th Cong., 1st Sess. 21 (1965) (amendments extending section 3568 to nonbailable offenses and lifting its limitation to statutes with minimum mandatory sentences were designed to “guarantee[] credit for pretrial custody”); H.R.Rep. No. 2058, 86th Cong., 2d Sess. 1 (1960) (purpose of amendment to section 3568 “is to make clear that the defendant receives credit for time spent in custody not only prior to trial but during the trial,” and “also to exclude credit for time spent in custody after sentence, such as while on appeal”). Once a sentence is imposed and becomes operative for the period of time at issue, it is artificial to maintain that custody nonetheless retains its preconviction character, that it remains conditional, unsettled, still dependent upon (and therefore “in connection with”) a trial court’s eventual disposition of other charges not yet adjudicated.4
Moreover, were we to read 18 U.S.C. § 3568 as authorizing presentence credit for time a prisoner serves after the imposition of a first sentence, we would alter the instruction a trial judge signals when he or she orders that the sentence imposed shall run concurrently with any sentence then “being served.” For example, assume a trial judge imposed a one-year sentence on a defendant and ordered it to run concurrently with a one-year sentence then being served, eight months of which had elapsed. We have little doubt that the sentencing judge in such a case would envision a second sentence outlasting the first by eight months. Precedent in point confirms that a federal sentence made concurrent with a sentence already being served does not operate in a “fully concurrent” manner. Rather, the second sentence runs together with the remainder of the one then being served. See United States v. Flores, 616 F.2d 840, 841 (5th Cir.1980); Wilson v. Henderson, 468 F.2d 582, 584 (5th Cir.1972).5
*445In his pro se brief, Shelvy correctly points out that the presentence credit for which 18 U.S.C. § 3568 provides is responsive to the situation of a person held in custody because of inability to make bail. See Brief for Appellant at 2. The current statute covers such cases and more. It applies to incarceration prior to the imposition of any sentence where the person is charged with a nonbailable offense or is not released pre-sentence for some other reason, for example, where a person is initially detained as a juvenile but later tried as an adult.6 Indeed, if the statute limited credit to days spent in custody because of inability to make bail, it appears that Shelvy would not have an arguable ease even for the credit accorded him. Jail records indicate that, while Shelvy was held in lieu of a money bond in case 1, the armed robbery case, he was held without bond in case 2, the murder case. See Brief for Amicus Curiae at 1. We therefore find unpersuasive the central assertion in Shelvy’s pro se brief that he was the victim of invidious discrimination because of his poverty.
The brief for amicus curiae suggests that we could grant “meaningful credit against the total period of [Shelvy’s] confinement,” and preclude the order of the two sentences from affecting the total time he serves, by “interrupting] the running of [the sentence in case 1]” and “making it commence six months later on November 20,1970.” Brief for Amicus Curiae at 20.7 But the opening statement in 18 U.S.C. § 3568 provides:
The sentence of imprisonment of any person convicted of an offense shall commence to run from the date on which such person is received at the penitentiary, reformatory, or jail for service of such sentence.
The concluding sentence of the section states:
No sentence shall prescribe any other method of computing the term.
Setting out the relevant legislative history, this court observed that Congress dominantly intended to provide “a firm date of sentence commencement.” United States v. Liddy, 510 F.2d 669, 674 (D.C.Cir.1974) (en banc), cert. denied, 420 U.S. 980, 95 S.Ct. 1408, 43 L.Ed.2d 661 (1975). The court in Liddy recognized authority in the district court to interrupt a sentence once it has commenced and thereby postpone the termination date of the sentence “beyond the time the sentence would have ended had it not been interrupted.” Id. We confront no such situation here. Neither district court order nor statute authorizes the interruption amicus suggests. We therefore have no warrant to treat the case 1 sentence as commencing six months after Shelvy was committed to a place of detention to await transportation to the penitentiary designated for service of that sentence.
Nor, in face of specific congressional instruction to the contrary, are we at liberty *446to regard the case 2 sentence as “commenc[ing] to run from some date prior to the sentence or some date before [Shelvy] actually commence[d] [its] service.” See S.Rep. No. 803, supra, at 2; H.R.Rep. No. 960, supra, at 2. Moreover, even if we were to ignore the concern of Congress embodied in 18 U.S.C. § 3568 to “prevent juggling with sentences,” id., and entertain the notion that “a sentencing judge has the discretion to provide that a sentence is to be retroactively concurrent with another sentence which has already been served,” it is evident that “no such order was made in this case.” See United States ex rel. Del Genio v. United States Bureau of Prisons, 644 F.2d 585, 589 (7th Cir.1980), cert, denied, 449 U.S. 1084, 101 S.Ct. 870, 66 L.Ed.2d 808 (1981) (rejecting petitioner’s argument that a later sentence, ordered to run concurrently with an earlier one, should be treated as having commenced prior to the date it was imposed).
Shelvy’s case 2 sentence, as pronounced, runs concurrently with the case 1 sentence then being served. No statute authorizes us to amend that direction so that the sentence in case 2 not only runs concurrently with the remainder of the sentence in case 1, but is shortened by the time already elapsed on the prior sentence.8 The anomaly that Shelvy would have been entitled to consideration for release six months earlier had he been sentenced on the case 2 charge first is no more curious than the one suggested by respondents:9 had Shelvy been charged in case 2 the day after imposition of the sentence in case 1, none of his presentence detention would have served to reduce the period of his incarceration; he would not have received effective credit even for the 233 days between arrest and first sentencing.10
Conclusion
We conclude that Shelvy is entitled to presentence credit only for days of incarceration during which he was not serving any sentence. He has received full credit for those days. We can accord him no more without straining the meaning of 18 U.S.C. § 3568 and departing from judicial understanding and precedent on what a “sentence to run concurrently with an earlier sentence” means. Therefore, the judgment from which this appeal has been taken is
Affirmed.
. Citing Preiser v. Rodriguez, 411 U.S. 475, 486-88, 93 S.Ct. 1827, 1834-35, 36 L.Ed.2d 439 (1973), the district court noted that although granting Shelvy’s application would not result in his immediate release from confinement, a habeas corpus petition appears to be an available means to seek the requested relief.
. Respondents stated that prison records indicated October 31, 1969, as the date of Shelvy’s commitment on the murder charge. The district court assumed, for purposes of ruling on Shelvy’s petition, that commitments in both cases occurred on September 24, 1969. See Shelvy v. Whitfield, No. 82-1555, slip op. at 1 n. 1 (D.D.C. July 30, 1982). We make the same assumption.
. Murder in the second degree, defined in D.C. Code § 22-2403, is punishable by imprisonment “for life or not less than 20 years.” D.C. Code § 22-2404. However, D.C.Code § 24-203, the Indeterminate Sentence Act, provides that a maximum sentence of life imprisonment must be accompanied by a minimum sentence not to exceed 15 years imprisonment. Thus Shelvy’s term was 15 years to life. Had the trial judge sentenced Shelvy to the lightest sentence permissible under § 22-2404, i.e., 20 years, § 24-203 would have made him eligible for parole in 6% years. See Frady v. United States Bureau of Prisons, 570 F.2d 1027, 1028-29 (D.C.Cir.1978) (quoting H.R.Rep. No. 677, 87th Cong., 1st Sess. 2 (1961)).
. The position that presentence credit does not include time spent serving another sentence is announced in instructions for administrative determinations of jail-time credit under 18 U.S.C. § 3568, see United States Department of Justice, Federal Prison System Program Statement No. 5880.24, para. 5.b.(2) (Sept. 5, 1979), and is reflected in prior court rulings. See O’Connor v. Rodgers, Habeas Corpus 233-68, aff’d, No. 22,853 (D.C.Cir. June 24, 1970) (noting that Chief Judge Bazelon would remand the case for clarification of the trial judge’s intention in the imposition of the concurrent sentences). We do not attribute precedential value to this court’s unpublished disposition. See D.C.Cir.R. 8(f). We simply note, in view of the dissent’s reading of the statute, that on a prior occasion, after full consideration, the court determined that the issue occasioned no need for an opinion. See D.C.Cir.R. 13(c).
. In Flores, the defendant was sentenced, after conviction, to ten years on one drug offense on February 12,1976, and, after a plea of guilty, to ten years on another drug offense on December 13, 1976, the latter sentence “ ‘to run concurrently with the sentence imposed [in the first case].’ ” 616 F.2d at 841. He sought, unsuccessfully, to vacate the second sentence, urging that he had entered the guilty plea on the misapprehension that the sentence would be considered to begin and terminate on the same dates as the prior sentence, and that his counsel had labored under the same misapprehension. The court held this erroneous construction of the meaning of a concurrent sentence insufficient to invalidate the plea bargain.
In Wilson, the defendant sought credit for 155 days actually served on a sentence imposed by the District Court for the District of Colum*445bia against a longer sentence subsequently imposed by the District Court for the Southern District of New York and ordered to run concurrently with the District of Columbia sentence the defendant was then serving. Credit was denied on the ground that a sentence cannot commence prior to the date it was pronounced even if it is to be served concurrently with a sentence already being served. 468 F.2d at 584. As in the case before us, the defendant in Wilson was awarded credit against both sentences for the period he spent in federal custody (204 days) prior to the first, District of Columbia, sentence. Id. at 583.
. See S.Rep. No. 750, 89th Cong., 1st Sess. 21 (1965) (nonbailable offenses); Federal Bail Procedures: Hearings on S. 2838, S. 2839, S. 2840 Before the Subcomm. on Constitutional Rights and the Subcomm. on Improvements in Judicial Machinery of the Comm, on the Judiciary, 88th Cong., 2d Sess. 135-36 (1964) (juveniles-tried-as-adults and nonbailable offenses).
. At our request, amicus curiae’s brief centered on this question: “Given the fact that Mr. Shelvy would have received the six months credit he now seeks had the sentencing dates been reversed, does 18 U.S.C. § 3568 require a different result because the sentence in the robbery case came first?” Brief for Amicus Curiae at 6. The brief is a careful, comprehensive development of the arguments in support of six months additional credit for Shelvy. The dissent considers “essential” further supplemental briefing and argument. Dissent at 448. Yet it cites not a single decision that even squints in support of a different outcome in Shelvy’s case.
. No doubt “judicial power,” see dissent at 448, existed to render Shelvy eligible for parole earlier. The sentencing judge in case 2 could have shortened Shelvy’s second degree murder sentence. See supra note 3. Instead, in face of contemporaneous interpretation of 18 U.S.C. § 3568, see supra note 4, and extant administrative procedures for computing jail-time credit, he sentenced Shelvy to the statutory maximum.
. Brief for Respondent-Appellees at 6.
. The days would have been credited against the sentence in case 1, but there would have been no presentence credit at all against the considerably longer sentence in case 2.