Opinion
WERDEGAR, J.Penal Code section 29331 offers state prisoners who participate in qualifying work, training and educational programs the privilege of earning “worktime credit” (id., subd. (a)) against their sentences. Ordinarily, the maximum rate at which a prisoner may earn worktime credit is 50 percent, or one day’s credit for each day’s participation.2 Other statutes make worktime credit unavailable, or available only at a reduced rate, to prisoners convicted of designated offenses. (E.g., §§ 2933.1 [violent offenses], 2933.2 [murder].) This case concerns section 2933.1, subdivision (a),3 which provides that “any person who is convicted of a felony offense listed in subdivision (c) of Section 667.5 [i.e., a violent offense] shall accrue no more than 15 percent of worktime credit, as defined in Section 2933.”4
The question before us is whether section 2933.1(a) restricts petitioner’s ability to earn worktime credit against a concurrent sentence for a nonviolent offense. Petitioner has completed a five-year term for the violent offense that made the section applicable and is now serving the remainder of a concurrent *76910-year term for a nonviolent offense. We hold that section 2933.1(a) limited to 15 percent the rate at which petitioner could earn worktime credit as long as he was serving the term for the violent offense, even though the concurrently punished nonviolent offense would not by itself have caused the section to apply; but once petitioner completed the term for the violent offense he became prospectively eligible to earn credit at a rate unrestricted by the section. We therefore reject both the People’s harsher and petitioner’s more lenient interpretations of the section.
I. Background
On March 18, 1999, following a jury trial, the Orange County Superior Court sentenced petitioner to 10 years in state prison for the offense of possessing a controlled substance for sale, plus enhancements.5 In a separate proceeding on April 6, 1999, pursuant to a guilty plea, a different judge of the same court sentenced petitioner to five years for the offense of assault with a deadly weapon other than a firearm, plus an enhancement.6 Because the assault caused great bodily injury, it triggered the 15 percent credit limitation of section 2933.1(a) as a “violent felony” described in section 667.5, subdivision (c). The judge at the second sentencing proceeding did not state that the two sentences would run consecutively; hence, the Penal Code made them concurrent by operation of law.7 (§ 669, 2d par.)
Petitioner was committed to state prison in 1999. At that time, the Department of Corrections (Department) calculated his release date as October 19, 2006. The Department based this decision on its understanding that section 2933.1(a) applied fully to both of petitioner’s sentences so that he would accrue only 15 percent worktime credit for the entire duration of his prison commitment, even after completing the shorter, five-year sentence for the violent felony. Petitioner challenged the Department’s decision in a petition for habeas corpus. The superior court, reasoning that section 2933.1(a) had no effect on petitioner’s sentence for the nonviolent offense, *770granted the writ and ordered the Department to recalculate petitioner’s release date. The Court of Appeal affirmed, and we granted review.
II. Discussion
Our role in construing section 2933.1(a), as with any statute, is to ascertain the Legislature’s intent so as to effectuate the purpose of the law. We accomplish this task if possible by giving the words of the statute their usual, ordinary meanings. (People v. Canty (2004) 32 Cal.4th 1266, 1276 [14 Cal.Rptr.3d 1, 90 P.3d 1168].) This case turns on the meaning of the phrase “any person who is convicted of a [violent] felony offense . . . .” (§ 2933.1(a).)8
As will appear, the effort to apply this seemingly plain language to the case at hand reveals ambiguities the Legislature apparently did not foresee.
The People argue that petitioner “is convicted” of a violent felony offense for purposes of calculating worktime credit because he served a term for a violent offense during his current prison commitment, even though he has completed that term and would be eligible for release, were it not for the time remaining on his longer concurrent sentence for a nonviolent offense. Petitioner, echoing the lower courts’ conclusions, contends that section 2933.1(a) has never restricted his ability to earn worktime credit against the longer concurrent sentence because, for purposes of that sentence, he is not convicted of a violent felony offense. Other possible interpretations of the section also exist, as we shall explain. Accordingly, the conclusion that section 2933.1(a) is ambiguous, at least as applied to the facts of this case, seems *771inescapable. Indeed, petitioner expressly argues the statute is ambiguous, and the Attorney General conceded the point during oral argument.
Because section 2933.1(a) is ambiguous, we may look beyond its language to other evidence that helps to elucidate the Legislature’s purpose, such as the statute’s background and history. (People v. Canty, supra, 32 Cal.4th 1266, 1277.) The purpose that motivated the section’s enactment, however, is clear only in the broadest terms: The Legislature wished to protect the public by delaying the release of prisoners convicted of violent offenses. (Stats. 1994, ch. 713, § 2, p. 3448 [declaration of urgency].) The general observation that a law was intended to delay release does not, in the face of ambiguous statutory language, answer the specific, practical questions of how long and under what circumstances release is to be delayed. Neither does the legislative history reveal any specific consideration of the problem of applying credits to concurrent sentences. Under these circumstances, lacking definitive guidance in the statute’s language or history, “our aim [must be] to provide ... a construction [of the statute] which is faithful to its language, which produces fair and reasonable results in a majority of cases, and which can be readily understood and applied by trial courts.” (In re Joyner (1989) 48 Cal.3d 487, 495 [256 Cal.Rptr. 785, 769 P.2d 967].) This is the practical approach to identifying legislative intent that we have followed in other cases addressing unforeseen difficulties in the implementation of California’s statutory credit system. (Ibid.; see also People v. Buckhalter (2001) 26 Cal.4th 20, 28-29 [108 Cal.Rptr.2d 625, 25 P.3d 1103]; People v. Bruner (1995) 9 Cal.4th 1178, 1194-1195 [40 Cal.Rptr.2d 534, 892 P.2d 1277] .)9
In searching for a reasonable construction of section 2933.1(a), we may at the outset reject a construction that, while arguably consistent with the section’s language, is almost certainly not what the Legislature intended. The phrase, “any person who is convicted of a [violent] felony offense” (§ 2933.1(a)), might conceivably refer simply to a point of historical fact. Read in this way, the statute would disqualify, for all time, any person who has ever been convicted of a violent offense from earning more than 15 percent worktime credit. Neither the People nor petitioner endorses this reading of the section. We may reasonably reject it because the Legislature typically uses different language when it intends to impose a continuing *772disability based on criminal history. Credit restrictions, enhancements and alternative sentencing schemes based on criminal history usually employ the past perfect tense (“has been convicted” or “previously has been convicted”) rather than the present tense (“is convicted”). (E.g., §§ 667, subds. (a)(1) & (b), 667.51, subd. (d), 667.6, subd. (a), 667.71, subd. (a), 2933.5, subd. (a)(1).) Similarly, section 2933.5 withholds all worktime credits from a “person who is convicted” and also “previously has been convicted two or more times” of a designated felony. (Id., subd. (a)(1), italics added.) We have relied on this observation about the Legislature’s practice to resolve other statutory ambiguities, as when we determined that a statute referred to current rather than past convictions in making any “person convicted of murder, rape or any other serious felony” (Welf. & Inst. Code, § 1732.5) ineligible for commitment to the Youth Authority. (People v. Woodhead (1987) 43 Cal.3d 1002, 1008-1010 [239 Cal.Rptr. 656, 741 P.2d 154].)
We may also reasonably reject the parties’ interpretations of section 2933.1(a). Both create unacceptable tension with the statutory language, and neither is entirely fair and reasonable.
As mentioned, the People argue that section 2933.1(a) restricts petitioner’s ability to earn worktime credit against his concurrent term for the nonviolent offense even though he has completed his term for the violent offense that caused section 2933.1(a) to apply. The People reject petitioner’s and the lower courts’ view that the section applies on an offense-by-offense basis. In the People’s view, section 2933.1(a) applies to offenders rather than to offenses, and applies to a designated offender’s entire period of confinement, provided the offender at some point during that period serves time for a violent offense. An offender’s time in prison, the People argue, must for purposes of credits be regarded as “a single, unitary period of confinement,” regardless of “whether that period of confinement is based upon multiple convictions or separate crimes.” Reading section 2933.1(a) in this way, petitioner’s total time in state prison would be eight years and six months, which represents the longer, 10-year concurrent term for a nonviolent offense minus 15 percent worktime credit.
We agree with the People’s interpretation of section 2933.1(a) in some respects but not in others. We may confidently assume that an offender serving a sentence that combines consecutive terms for violent and nonviolent offenses is subject to the credit restriction imposed by section 2933.1(a) for the entire sentence. Under the Determinate Sentencing Act (§ 1170 et seq.), multiple consecutive determinate terms must be combined into a single, “aggregate term of imprisonment for all [such] convictions” (§ 1170.1, subd. (a)) that merges all terms to be served consecutively and complies with *773the rules for calculating aggregate terms (e.g., one-third the base term for subordinate terms and specific enhancements applicable to subordinate terms (ibid.)), whether or not the consecutive terms arose from the same or different proceedings (ibid.-, see also § 669; Cal. Rules of Court, rule 4.452). To suggest that a prisoner serving an aggregate term serves the component terms and enhancements in any particular sequence would be a meaningless abstraction. For this reason, when an aggregate term includes time for a violent offense, at any point during that term the prisoner literally “is convicted of a [violent] felony offense” (§ 2933.1(a)) and actually is serving time for that offense. Accordingly, a restriction on credits applicable to “any person who is convicted of a [violent] felony offense” (ibid.) logically applies throughout the aggregate term.
The People’s effort to apply the same logic to concurrent terms is not convincing. A court that decides to run terms consecutively must create a new, “aggregate term of imprisonment” (§ 1170.1, subd. (a)) into which all the consecutive terms merge, but no principle of California law merges concurrent terms into a single aggregate term. Section 1170.1, which articulates the statutory mandate and authority for creating aggregate consecutive terms, says nothing about concurrent terms. Furthermore, a later sentencing court may not change a prior sentencing court’s discretionary decision to make a particular term concurrent rather than consecutive. (Cal. Rules of Court, rule 4.452(3).)10 The determinate sentencing law, in short, does not support the People’s argument that all of an inmate’s overlapping terms necessarily constitute a single, unified term of confinement for purposes of worktime credit.
Neither do the other statutes on which the People rely support their argument. Section 667.5, subdivision (g), defines “prior separate prison term for purposes of this section” (italics added) as including both concurrent and consecutive terms. But the section has nothing to do with credits; its purpose is to avoid enhancing a sentence for a “prior separate prison term” (§ 667.5, subd. (a)) more than once for a single prior stay in prison. Section 2933, the statute authorizing worktime credits, begins by stating the Legislature’s intent that persons convicted and sentenced under the Determinate Sentencing Act “serve the entire sentence imposed by the court, except for a reduction in the *774time served” for performance in qualified work programs. (Id., subd. (a).) But the section does not provide that separate, concurrent sentences merge for purposes of credits. Neither does section 2900, subdivision (a), which simply provides that “[t]he term of imprisonment fixed by the judgment . . . commences to run only upon the actual delivery of the defendant into the custody of the Department of Corrections . . . .”11
The People also attempt to derive their proposed rule that all of a prisoner’s overlapping terms must, for purposes of credits, be viewed as a single, unitary period of confinement from the language of section 2933.1. The specific language on which the People rely, however, appears not in subdivision (a) but in subdivision (c), and it concerns not postsentence worktime credits under section 2933 but presentence credits under section 4019. Section 2933.1, subdivision (c),12 provides that “the maximum credit that may be earned against a period of confinement in, or commitment to, a county jail [or other local facility] following arrest and prior to placement in the custody of the Director of Corrections, shall not exceed 15 percent of the actual period of confinement for any person specified in subdivision (a).” (Italics added.) Thus, a person who spends time in presentence (including pretrial) confinement and is eventually convicted of a violent offense may earn, as a credit against his prison sentence, no more than 15 percent of the actual time he spent in presentence confinement, regardless of the offenses for which he was charged. This was the holding of People v. Ramos (1996) 50 Cal.App.4th 810, 815-817 [58 Cal.Rptr.2d 24] (Ramos). All other published decisions addressing the same issue about presentence credits have followed Ramos. (People v. Duran (1998) 67 Cal.App.4th 267, 270 [78 Cal.Rptr.2d 884]; People v. Aguirre (1997) 56 Cal.App.4th 1135, 1141 [66 Cal.Rptr.2d 77]; People v. Palacios (1997) 56 Cal.App.4th 252, 255-256 [65 Cal.Rptr.2d 318].)
*775The People insist that Ramos, supra, 50 Cal.App.4th 810, disposes of the different issue before us. It does not. The defendant in Ramos, after a period of presentence confinement, was convicted of a variety of violent and nonviolent offenses and sentenced to a single, aggregate term of 22 years, which included among other things an eight-month consecutive term for a nonviolent offense. (Id., at p. 814.) The defendant argued that section 2933.1(c) did not affect his ability to earn credit under section 4019 for presentence custody attributable to his nonviolent offenses. Assuming the correctness of that argument, the defendant further contended that he had accrued presentence credit at two different rates: the reduced rate of 15 percent against the portion of his presentence confinement attributable to the violent offense, and at a higher rate (see § 4019, subd. (f)) against the portion attributable to the nonviolent offense. (Ramos, at p. 817.) The court reasonably rejected these arguments because “the language of section 2933.1 [did] not support [Ramos’s] position.” (Ramos, at p. 817.) Section 2933.1, the court reasoned, “limits to 15 percent the maximum number of conduct credits[13] available to ‘any person who is convicted of a felony offense listed in Section 667.5.’ That is, by its terms, section 2933.1 applies to the offender not to the offense and so limits a violent felon’s conduct credits irrespective of whether or not all his or her offenses come within section 667.5.” (Ramos, supra, at p. 817, quoting § 2933.1(a).)
The Ramos court’s statement that “section 2933.1 applies to the offender not to the offense” (Ramos, supra, 50 Cal.App.4th 810, 817) makes sense in the context in which the court spoke—that of presentence credits authorized by section 4019 and limited by section 2933.1(c). A period of presentence confinement is indivisibly attributable to all of the offenses with which the prisoner is charged and of which he is eventually convicted. The defendant’s argument in Ramos would have required the court to parse such a single, unitary period of presentence confinement into hypothetical, overlapping terms eligible to earn credit at different rates. Such a result finds no support in the language of subdivision (c), which limits the credits a prisoner may earn against an “actual period of confinement” (§ 2933.1(c), italics added) following arrest and before sentencing. The People here, departing from the actual holding of Ramos, would read subdivision (c) as if it qualified subdivision (a) by defining all of a prisoner’s postsentence time in state prison as a single “actual period of confinement” (§ 2933.1(c)) for purposes of postsentence worktime credit. Although subdivision (c) does refer to subdivision (a),14 it does so “only to clarify the intended target population” *776of subdivision (c). (People v. Aguirre, supra, 56 Cal.App.4th 1135, 1140.) In other words, subdivision (c) explains that its limitation on presentence credit takes effect only when a person who has served “an actual period of [presentence] confinement” (§ 2933.1(c)) becomes, by subsequent conviction of a violent offense in a proceeding to which the presentence custody is attributable, a “person specified in subdivision (a)” (§ 2933.1(c), italics added), namely, a “person who is convicted of a [violent] felony offense” (§ 2933.1(a)). Subdivision (c) says nothing at all about postsentence credit. Thus, to read subdivision (c) as limiting postsentence credits or qualifying subdivision (a), as the People here would read it, finds no support in the relevant statutory language.
The People attempt to find evidence of legislative intent supporting their position in a letter written by Assemblyman Richard Katz, who sponsored the bill that became section 2933.1 (Assem. Bill No. 2716 (1993-1994 Reg. Sess.)), to the Clerk of the Assembly and printed by unanimous consent in the Assembly Journal after both houses of the Legislature had passed the bill. But the letter itself is ambiguous. In it, the author states: “This letter is to clarify my intent, and that of the Legislature, in writing and enacting AB 2716 ... to ensure that the maximum reduction [for worktime credits] . . . from a defendant’s term of imprisonment imposed as a result of a violent felony . . . be fifteen percent. [][] In enacting Penal Code section 2933.1, it is my intent and that of the Legislature to ensure that the maximum fifteen percent reduction apply to a defendant’s entire term of imprisonment, so long as the defendant has been convicted of at least one violent felony . . . .” (Assemblyman Richard Katz, letter to Dotson Wilson, Chief Clerk of Assem., August 31, 1994, printed at 6 Assem. J. (1993-1994 Reg. Sess.) p. 9353.) The letter’s first sentence, which refers to “a defendant’s term of imprisonment imposed as a result of a violent felony” (ibid., italics added), might be read as supporting petitioner’s argument that section 2933.1(a) applies on an offense-by-offense basis. The letter’s second sentence, which refers to an “entire term” (Assemblyman Richard Katz, letter to Dotson Wilson, supra, italics added), has two possible meanings: it could mean that the restriction applies to a prisoner’s entire term for a violent offense, even if the term is an aggregate term (see § 1170.1, subd. (a)) combining consecutive terms for both violent and nonviolent offenses;15 or, using the word “term” in a less *777formally correct sense, it could refer to a prisoner’s entire period of confinement in state prison, as the People here argue. The letter offers no basis for resolving the ambiguity; nor does it specifically address the question of whether the credit restriction proposed in the bill would apply to a separate, concurrent term for a nonviolent offense.
Of no more assistance in the present case is Governor Wilson’s message to the Assembly upon signing the bill that became section 2933.1. The Governor wrote that the “bill would limit to 15% the credit inmates in state prison or local custody could earn to reduce their prison sentences for violent crimes.” (Governor’s message to Assem. on Assem. Bill No. 2716 (Sept. 21, 1994) 6 Assem. J. (1993-1994 Reg. Sess.) p. 9490.) This brief, general statement, which does not specifically address the treatment of concurrent terms, is consistent with both the People’s and petitioner’s interpretations of section 2933.1.
The People’s reading of section 2933.1(a) creates tension with the statutory language in this way: Because petitioner has already served the term for the violent offense that caused the section to apply, tire statement that he “is convicted of a [violent] felony offense” (ibid.) is true only as a matter of historical fact, i.e., he was once convicted of a violent offense. But we have already rejected, as contrary to the Legislature’s probable intent, the argument that section 2933.1(a) treats a conviction for a violent offense as a continuing disability that restricts an offender’s ability to earn worktime credits even after he has served his sentence for that offense. Except in this inapplicable sense, to say that petitioner at the present time “is convicted” (ibid.) of a violent offense is not correct. Today, his conviction for the violent offense gives the Department no claim to his physical custody; but for the time remaining on the separate, concurrent term for the nonviolent offense, he would be entitled to release. For the same reason, given the statute’s ambiguity, the People’s interpretation of section 2933.1(a) is not entirely fair (to petitioner or others in his situation) or reasonable. (People v. Buckhalter, supra, 26 Cal.4th 20, 28-29; People v. Bruner, supra, 9 Cal.4th 1178, 1194-1195; In re Joyner, supra, 48 Cal.3d 487, 495.)16
*778Petitioner’s own interpretation of section 2933.1(a) also creates tension with the statutory language and is likewise neither fair nor reasonable. Following the lower courts, petitioner interprets section 2933.1(a) as having no effect whatsoever on his concurrent sentence for the nonviolent offense. As a result, petitioner continues, he has from the time he entered prison accrued credit at two different rates—15 percent on the term for the violent offense and 50 percent on the term for the nonviolent offense. Reading section 2933.1(a) in this way, petitioner’s total time in custody would be five years, which represents the 10-year term for a nonviolent offense minus 50 percent credit. Petitioner concedes, as he must, that section 2933.1(a) applies to the term for the violent offense, but he denies the section has any practical impact on the duration of his commitment to state prison. This is because he has already served the credit-adjusted term for his violent felony offense (four years and three months, or five years minus 15 percent credit) and because the longer, credit-adjusted term for the nonviolent offense will, as he reads section 2933.1(a), keep him in prison a total of only five years—exactly the same time he would have served had he never been convicted of and sentenced for the violent offense.
Petitioner’s interpretation of section 2933.1(a) would rob the section of any effect in his own case and thus entirely frustrate, if only in similar cases, the Legislature’s purpose of delaying the release of violent offenders. Petitioner’s interpretation thus cannot be described as fair (to the People) or reasonable. (People v. Buckhalter, supra, 26 Cal.4th 20, 28-29; People v. Bruner, supra, 9 Cal.4th 1178, 1194—1195; In re Joyner, supra, 48 Cal.3d 487, 495.) Petitioner’s interpretation also creates tension with the statutory language in this way: During any period of time when petitioner is serving time in prison for both the violent offense and the nonviolent offense, petitioner most certainly “is convicted of a [violent] felony offense” (§ 2933.1(a), italics added) in every relevant sense. Thus, to permit him to accrue worktime credit *779during such a period of imprisonment at the rate of 50 percent for any purpose literally conflicts with the language of section 2933.1(a).
The arguments supporting petitioner’s interpretation of section 2933.1(a) are not persuasive. Petitioner first argues that worktime credit is accrued on an offense-by-offense basis, at least when the offenses are punished with separate, concurrent terms. He bases this argument on the so-called strict causation rule, under which a prisoner “is not entitled to credit for presentence confinement unless he shows that the conduct which led to his conviction was the sole reason for his loss of liberty during the presentence period.” (People v. Bruner, supra, 9 Cal.4th 1178, 1191, italics added.) Thus, for example, a prisoner who serves a period of presentence custody on Florida charges is not entitled to credit against his subsequent prison sentence on California charges, even though a California hold was in effect throughout the period of presentence custody. (In re Joyner, supra, 48 Cal.3d 487, 492.) “Taking the logic that credits should be allocated to the term for which they accrued and applying it to the credits limitation situation here,” petitioner argues, “results in a sensible general rule that the credits limitation applies to the term of imprisonment that is based on a qualifying offense.” The argument lacks merit. The strict causation rule has no recognized application outside the context of presentence credits.
Petitioner next argues that the rule of lenity compels us to adopt his interpretation of section 2933.1(a). We disagree. “[Although true ambiguities are resolved in a defendant’s favor, an appellate court should not strain to interpret a penal statute in defendant’s favor if it can fairly discern a contrary legislative intent.” (People v. Avery (2002) 27 Cal.4th 49, 58 [115 Cal.Rptr.2d 403, 38 P.3d 1].) As we have explained, petitioner’s interpretation of section 2933.1(a) would require us literally to violate the statute’s command that “any person who is convicted of a [violent] felony offense . . . shall accrue no more than 15 percent of worktime credit” (ibid.), at least during the period of custody when petitioner is actually convicted of and serving a term for a violent offense. Moreover, as we have also explained, petitioner’s interpretation of the section would leave the section without any effect on his own sentence, thus frustrating the Legislature’s goal of ensuring that violent felons serve a great portion of their sentences.
In any event, resort to the rule of lenity is unnecessary. An interpretation of section 2933.1(a) exists that is faithful to its language and to what we know of the Legislature’s purpose, produces fair and reasonable results, and can be readily understood and applied. Lacking definitive guidance in the language or history of the statute, our aim must be to identify such an interpretation. (E.g., In re Joyner, supra, 48 Cal.3d 487, 495.) As mentioned *780at the outset, we interpret the section as follows: Section 2933.1(a) limits to 15 percent the rate at which a prisoner convicted of and serving time for a violent offense may earn worktime credit, regardless of any other offenses for which such a prisoner is simultaneously serving a sentence.17 On the other hand, section 2933.1(a) has no application to a prisoner who is not actually serving a sentence for a violent offense; such a prisoner may earn credit at a rate unaffected by the section.18
Our interpretation is more faithful to the language of section 2933.1(a) than is either the People’s or petitioner’s interpretation. Unlike the People’s interpretation, our interpretation does not require us to treat a person who is no longer subject to imprisonment for a violent offense as a person who “is convicted” (§ 2933.1(a)) of such an offense. Unlike petitioner’s interpretation, our interpretation does not require us to treat a person who is currently serving time for a violent offense as a person who is not convicted of such an offense. Our interpretation is also faithful to what we know of the Legislature’s purpose because it effectively limits the rate at which petitioner and others in his situation can earn worktime credit while serving sentences for violent offenses. Under our interpretation, petitioner will accrue credit at the rate of 15 percent against his first five years in prison and at the rate of 50 percent for his second five years. He will thus serve a total of six years and nine months, which represents five years minus 15 percent credit, plus five *781years minus 50 percent credit.19 Our interpretation is fair and reasonable both to the People, because it imposes a real restriction on a violent offender’s ability to earn worktime credits, and to petitioner, because the restriction ends when the term for the violent offense has been served.20 Of course, our interpretation of section 2933.1 leaves the Legislature free to amend the section if and as it chooses.
HI. Disposition
The judgment of the Court of Appeal is affirmed in part and reversed in part, and the case is remanded for further proceedings consistent with the views set forth herein.
George, C. J., Kennard, J., and Moreno, J., concurred.
All further citations to statutes are to the Penal Code, except as noted.
Prisoners assigned to conservation camps may earn two days’ worktime credit for each day’s service. (§ 2933.3.)
Hereafter section 2933.1(a).
Section 2933.1(a) uses the term “worktime credit” to refer to the type of postsentence credit created, and expressly given that name, by section 2933. This opinion uses the term only in that statutory sense. To avoid confusion, we note the term “worktime credit” is sometimes used in a nonstatutory sense to refer to presentence credit awarded for willingness to perform assigned labor (§ 4019, subd. (b)), in order to distinguish it from presentence credit awarded for compliance with rules and regulations (id., subd. (c)). (E.g., People v. Cooper (2002) 27 Cal.4th 38, 40 [115 Cal.Rptr.2d 219, 37 P.3d 403].) Both forms of presentence credit are also sometimes referred to as “conduct credit.” (E.g., ibid.)
The 10-year sentence represents the middle term of two years for possession of a controlled substance for sale (Health & Saf. Code, § 11378; see § 18), two years for committing that felony for the benefit of a criminal street gang (§ 186.22, subd. (b)(1)), three years for having served three prior prison terms (§ 667.5, subd. (b)), and three years for having committed a prior drug-related offense (Health & Saf. Code, § 11370.2, subd. (b)).
The five-year sentence represents the lower term of two years for assault with a deadly weapon other than a firearm (§ 245, subd. (a)(1)) plus three years for causing great bodily injury (§ 12022.7).
The subsequently prepared minute order and abstract of judgment reflect the court’s implicit decision to sentence concurrently.
Section 2933.1 provides in Ml:
“(a) Notwithstanding any other law, any person who is convicted of a felony offense listed in subdivision (c) of Section 667.5 shall accrue no more than 15 percent of worktime credit, as defined in Section 2933.
“(b) The 15-percent limitation provided in subdivision (a) shall apply whether the defendant is sentenced under Chapter 4.5 (commencing with Section 1170) of Title 7 of Part 2 or sentenced under some other law. However, nothing in subdivision (a) shall affect the requirement of any statute that the defendant serve a specified period of time prior to minimum parole eligibility, nor shall any offender otherwise statutorily ineligible for credit be eligible for credit pursuant to this section.
“(c) Notwithstanding Section 4019 or any other provision of law, the maximum credit that may be earned against a period of confinement in, or commitment to, a county jail, industrial farm, or road camp, or a city jail, industrial farm, or road camp, following arrest and prior to placement in the custody of the Director of Corrections, shall not exceed 15 percent of the actual period of confinement for any person specified in subdivision (a).
“(d) This section shall only apply to offenses listed in subdivision (a) that are committed on or after the date on which this section becomes operative.”
When a statute is capable of more than one construction, “ ‘[w]e must . . . give the provision a reasonable and commonsense interpretation- consistent with the apparent purpose and intention of the lawmakers, practical rather than technical in nature, which upon application will result in wise policy rather than mischief or absurdity.’ ” (Renee J. v. Superior Court (2001) 26 Cal.4th 735, 744 [110 Cal.Rptr.2d 828, 28 P.3d 876], quoting Marshall M. v. Superior Court (1999) 75 Cal.App.4th 48, 55 [88 Cal.Rptr.2d 891].)
The Penal Code, by use of the plural form “terms,” implicitly recognizes that a prisoner can have multiple terms that do not merge. For example, “[t]he Department of Corrections shall advise the court pronouncing the second or other subsequent judgment of the existence of all prior judgments against the defendant, the terms of imprisonment upon which have not been completely served.” (§ 669, 3d par., italics added.) Moreover, when a court sentences without knowledge of existing terms, it may within 60 days thereafter “determine how the term of imprisonment upon the second or other subsequent judgment shall run with reference to the prior incompleted [Ac] term or terms of imprisonment.” (Id., 2d par., italics added.)
The dissent, relying on older decisions interpreting the specific language of sentencing schemes that have long since been repealed, unsuccessfully attempts to construct a nonstatutory general rule to the effect that all of a prisoner’s terms merge for purposes of credits. (See dis. opn. of Chin, J., post, at pp. 783-785, citing In re Cowen (1946) 27 Cal.2d 637 [166 P.2d 279], In re Albori (1933) 218 Cal. 34 [21 P.2d 423], Ex Parte Dalton (1875) 49 Cal. 463.) None of the cited cases offers any assistance in interpreting the different language of section 2933.1(a) or the present Determinate Sentencing Act (§ 1170 et seq.). Neither can any guidance be found in more recent decisions using the term “aggregate sentence” in a nonstatutory, colloquial sense as including concurrent terms while not addressing the question before us. (See dis. opn. of Chin, J., post, at pp. 784—785, fn. 3, citing People v. Williams (2004) 34 Cal.4th 397, 401 [19 Cal.Rptr.3d 619, 98 P.3d 876], People v. McFarland (1989) 47 Cal.3d 798, 801 [254 Cal.Rptr. 331, 765 P.2d 493], People v. Bruce G. (2002) 97 Cal.App.4th 1233, 1236 [118 Cal.Rptr.2d 890], People v. Cole (1994) 23 Cal.App.4th 1672, 1674 [28 Cal.Rptr.2d 788], and People v. Parrott (1986) 179 Cal.App.3d 1119, 1122 [225 Cal.Rptr. 293].)
Hereafter section 2933.1(c).
13 That is, pretrial credits under section 4019. See page 768, footnote 4, ante.
“Notwithstanding Section 4019 [which authorizes presentence credits] or any other provision of law, the maximum credit that may be earned against a period of confinement in, or commitment to, a county jail [or other local facility] following arrest and prior to placement in the custody of the Director of Corrections, shall not exceed 15 percent of the actual period of confinement for any person specified in subdivision (a).” (§ 2933.1(c), italics added.)
At oral argument, the People questioned whether our interpretation of section 2933.1(a) could readily be applied by the Department. We have no reason to doubt that it can be. The Department calculates a prisoner’s earliest possible release date (EPRD), adjusted for worktime credit, by reference to a “controlling term.” (Cal. Dept. of Corrections, Operations Manual (2000) § 73030.8.13.) Petitioner’s shorter concurrent term for the violent offense properly controlled the rate at which he accrued worktime credit only until he completed that term. Thereafter, the longer concurrent term for the nonviolent offense—the term which alone gave *778the Department a valid claim to petitioner’s continuing physical custody—properly controlled his future ability to earn worktime credit. The Department’s rules for calculating worktime credit already provide that a prisoner’s “EPRD is projected each time . . . there is a change in credit earning status.” (Ibid.) Under our interpretation of section 2933.1(a), the expiration of a term for a violent offense, leaving only a concurrent term for a nonviolent offense, constitutes a change in credit earning status.
The dissent, noting that the Department’s current practice in awarding worktime credit differs from our conclusion about how credit should be awarded, questions on that basis whether the Department can readily apply our holding. (Dis. opn. of Chin, J., post, at pp. 794-796.) That the Department recognizes it must already track changes in credit earning status suggests it can apply our holding. In any event, the Department has no power to adopt a regulation or practice that conflicts with a final, authoritative judicial interpretation of section 2933.1(a).
Indeed, to say precisely this may well have been the author’s intention. The concern had been expressed that the proposed legislation might require the Department to calculate separate rates of credit accrual for “violent offenses running consecutively to non-violent offenses”— something the Department’s computer system was apparently unable to do and would therefore need to have been done manually. (Enrolled Bill Rep. on Assem. Bill No. 2716 (1993-1994 Reg. Sess.) Aug. 30, 1994, p. 3.) The same concern had been raised by the California Probation, Parole and Correctional Association while the original version of the bill that became section 2933.1 (Assem. Bill No. 113 (1993-1994 Reg. Sess.); see p. 780, fn. 18, post)
*777was pending in the Legislature. (Executive Director Susan Cohen, Cal. Probation, Parole and Correctional Assn., letter to Assemblyman Richard Katz, Apr. 15, 1993.)
We grant the People’s request for judicial notice of the legislative history of section 2933.1.
Unless, of course, one of those other offenses more severely restricts the prisoner’s ability to earn worktime credit. (E.g., § 2933.2, subd. (a) [eliminating worktime credit altogether for persons convicted of murder].)
The dissent argues that if the Legislature in passing section 2933.1(a) had “wanted to limit the statute’s application as the majority now does, it knew how to do so expressly.” (Dis. opn. of Chin, J., post, at p. 786, fn. 4.) As evidence, the dissent offers the language of Assembly Bill No. 2306 (1991-1992 Reg. Sess.) (as amended Apr. 21, 1992), which would have provided that a defendant convicted of a specified offense “shall accrue no more than 15 percent worktime credit against his or her term of imprisonment for that offense . . . .” (Id., § 1, italics added; see dis. opn. of Chin, I., post, at p. 786, fn. 4.) In fact, the italicized language would not have codified our interpretation of section 2933.1(a); it would have codified the interpretation of petitioner, who argues that section 2933.1(a) applies on an offense-by-offense basis. (See ante, at pp. 770, 778 et seq.) Rejecting petitioner’s argument, we interpret section 2933.1(a) as applying to a prisoner’s entire sentence, so long as the prisoner is serving time for a violent offense. (See ante, at p. 779 et seq.)
Furthermore, the bill to which the dissent refers was never enacted; nor did it become section 2933.1 by subsequent amendment. Instead, the bill died in committee in an earlier session of the Legislature and never came to a vote on the floor. (6 Assem. J. (1991-1992 Reg. Sess.) p. 10419.) Section 2933.1, as enacted and codified, was introduced as Assembly Bill No. 113 during the 1993-1994 Regular Session and was, later in the same session, redesignated and enacted as Assembly Bill No. 2716. To attempt to infer a subsequent Legislature’s collective knowledge and intent from language that an earlier and differently composed Legislature, acting as a whole, neither adopted nor rejected is irrational.
The proposed credit-adjusted term of six years and nine months is shorter than the term proposed by the People (eight years and six months) and longer than the term proposed by petitioner (five years).
The dissent erroneously asserts that, under our interpretation, petitioner will serve less time in prison “because [he] committed a nonviolent felony in addition to the violent felony,” and that our interpretation of section 2933.1 is thus “unfair to the People and absurd.” (Dis. opn. of Chin, J., post, at p. 793.) What the dissent apparently means is that section 2933.1(a) does not restrict petitioner’s ability to earn credits as much as it theoretically might, because petitioner’s three one-year enhancements for having served prior prison terms are attached to the sentence for the nonviolent felony instead of to the sentence for the violent felony. This unusual circumstance, however, is the result not of our holding in this case but of the second sentencing court’s discretionary decision not to run the new sentence for the violent felony consecutively to the existing sentence for the nonviolent felony. (See § 669.) Had the court done so, the longer base term for the violent felony (two, three or four years; see § 245, subd. (a)(1)) would necessarily have become the principal term (§ 1170.1, subd. (a)), the shorter base term for the nonviolent felony (18 months, or two or three years; see § 18) would necessarily have become the subordinate term (§ 1170.1, subd. (a)), the prior prison term enhancements would necessarily have attached to the principal term (ibid.), and the 15 percent credit limitation of section 2933.1(a) under our holding would have applied to petitioner’s entire consecutive sentence.