delivered the Opinion of the Court.
1 1 While serving a sentence in an unrelated case (the original sentence), the defen*623dant, Joseph Phillip Diaz, punched a prison guard (the first assault). Less than three months later, while still serving his original sentence, Diaz threw a cup that hit another guard in the mouth (the second . assault). The district attorney charged him in two cases with second degree assault of a detention center employee. Diaz finished serving his original sentence before trial in either case. Trial for the second assault preceded trial for the first. A jury found Diaz guilty, and the court sentenced him to ten years in prison for the second assault. Shortly thereafter, another jury found Diaz guilty of the first assault, and the court sentenced him to ten years consecutive to the ten years already imposed for the second assault.
2 A majority of a division of the court of appeals held that the trial court erred by ruling that section 18-8-203(1)(f), CRS. (2014), required that the sentence for the first assault be served consecutively to the sentence for the second assault.1 People v. Diaz, 2012 COA 158M, ¶ 19, -- P.3d --. We granted certiorari to consider whether the court of appeals erred by concluding that under section 18-8-203(1)(f) mandatory consecutive sentencing applies only to the sentence the defendant was serving at the time of the assault.
3 We hold that section 18-8-208(1)(f) requires a consecutive sentence if, at the time of sentencing, the defendant is serving any other sentence. Therefore, we reverse the court of appeals and remand for further proceedings consistent with this opinion.
I. Facts and Procedural History
T 4 On August 11, 2009, Diaz was serving a sentence at the Colorado State Penitentiary ("CSP") for felony menacing (the original sentence). While CSP conducted a mandatory strip search of the defendant during the process of transferring him to a different cell after an incident, the defendant punched one of the guards in his eye with a closed fist. According to that guard, the defendant had blood on his hand at the time the defendant struck him. Consequently, medical personnel also took blood from the guard to verify there was no blood-borne pathogen exposure. This incident became case number 09CR332 (the first assault). On September 29, 2009, the district attorney charged Diaz with see-ond degree assault of a detention center employee under section 18-3-2083(1)(f) for the first assault.
T5 On October 22, 2009, while still in custody at CSP for his original sentence and now with a new charge pending for the first assault, Diaz threw water in a guard's face as she attempted to collect his food tray. While she cleared the water from her glasses so she could see, the defendant reached through the tray slot and threw the cup at her head hard enough to require two stitches to her lower lip. This incident gave rise to case number 09CR417 (the second assault). The district attorney subsequently charged the defendant with second degree assault of a detention center employee under section 18-3-2083(1)(f) for the second assault.
T6 Before trial in either case, Diaz finished serving his original sentence.
T7 Trial for the second assault preceded trial for the first, possibly because of delays related to evaluating the defendant's sanity and his competency to stand trial. On December 1, 2010, a jury found Diaz guilty, and, on January 24, 2011, the court sentenced him to ten years in prison for the second assault.2 On January 25, 2011, another jury found Diaz guilty of the first assault. After the guilty verdict, the People dismissed two habitual criminal counts in the ease involving the first *624assault. On February 9, 2011, the court sentenced him to another ten years for the first assault, consecutive to the ten years already imposed for the second assault.3
1 8 Although the trial court equivocated on this point during the sentencing hearing on February 9, 2011, the court made several remarks at the conclusion of the hearing strongly suggesting that it construed the statute to require a consecutive sentence for the first assault.4 It is the trial court's decision to impose what it perceived as a mandatory consecutive sentence for the first assault that is at issue in this appeal.
II. Standard of Review
19 Statutory interpretation is a question of law we review de novo. Smith v. Exec. Custom Homes, Inc., 230 P.3d 1186, 1189 (Colo.2010); Hendricks v. People, 10 P.3d 1231, 1235 (Colo.2000).
III. Analysis
T10 Section 18-8-208(1)(f) reads in pertinent part:
A person commits the crime of assault in the second degree if: ... [while lawfully confined or in custody, he or she knowingly and violently applies physical force against the person of a peace officer.... A sentence imposed pursuant to this paragraph (f) shall be served in the department of corrections and shall run consecutively with any sentences being served by the offender ....
(Emphasis added.)
111 The question for us is the point in time to which the phrase "any sentences being served by the offender" refers. The prosecution argues that the term "any" plainly refers to any sentences the offender is serving at the time of the sentencing. The defendant argues, and the majority below held (see Diaz, 112), that the phrase is ambiguous and applies only to sentences the offender was serving at the time of the as-sqult.
112 When construing a statute our primary purpose is to ascertain and effectuate the intent of the General Assembly. Romero v. People, 179 P.3d 984, 986 (Colo. 2007). If the statutory language is clear and unambiguous, no further statutory analysis is required. Id. We construe the statute as a whole, in an effort to give consistent, harmonious, and sensible effect to all its parts, and we read the words and phrases in context and construe them according to the rules of grammar and common usage. § 24-101, C.R.S. (2014); Davison v. Indus. Claim Appeals Office, 84 P.3d 10283, 1029 (Colo.2004). "We do not add words to the statute or subtract words from it." Turbyne v. People, 151 P.3d 568, 567 (Colo.2007).
113 But if the statutory language is susceptible of more than one reasonable interpretation, it is ambiguous and we may *625apply other rules of statutory interpretation. Vensor v. People, 151 P.3d 1274, 1277 (Colo. 2007). "The plainness or ambiguity of statutory language is determined by reference to the language itself, the specific context in which that language is used, and the broader context of the statute as a whole." Robinson v. Shell Oil Co., 519 U.S. 837, 841, 117 S.Ct. 848, 136 L.Ed.2d 808 (1997).
A. The Plain Language
{14 The majority below found the plain language ambiguous: "[QJuoting the statute simply begs the question: 'with any sentence being served' when?" Diag 117 n.2. We disagree for several reasons.
115 First, we agree with Judge Russel, who in his dissent opined that "this phrase means just what it says-'with any sentences being served.'" Diag 128 (Russel, J., dissenting). The construction of the majority below requires us to add words-that is, to read the phrase "at the time of the assault" into the statute. See People v. Benavides, 222 P.3d 391, 394 (Colo.App.2009) (interpreting section 18-8-208(1)(f) and rejecting a similar argument). "But, in interpreting a statute, we must accept the General Assembly's choice of language and not add or imply words that simply are not there." Id. at 393-94. Like the court in Benavides, we refuse the defendant's invitation to venture into legislative territory. Accord Turbyne, 151 P.3d at 567 ("We do not add words to the statute ...."); see also id. at 568 ("[Wle cannot supply the missing language and must respect the legislature's choice of language.").
T 16 Second, the phrase in question begins with a reference to imposition of sentence: "A sentence imposed pursuant to this paragraph ()...." This indicates that the time at issue is the time the sentence is imposed, not the time of assault.
T 17 Third, it is illogical to require a consecutive sentence only if the offender is still serving the sentence for which he was imprisoned at the time of the assault because section 18-8-208(1)(f), by its terms, also prohibits assaults that occur before a sentence is even imposed-that is, when an offender is "lawfully confined or in custody as a result of being charged with ... a crime." See § 18-3-203(1)(f) (emphasis added); see also Benavides, 222 P.8d at 894 (noting that the provision also encompasses those who have been charged with a crime and requiring a consecutive sentence in that situation).
T 18 Last, had the legislature intended that the assault sentence at issue here be consecutive only to the sentence being served at the time of the assault, it could have said just that, It has certainly demonstrated the capacity to impose such a requirement in other provisions of the criminal code. See Benavi-dez, 222 P.Bd at 894 (observing that the legislature could have added language under section 18-3-2083(1)(f) similar to the language in the escape statute found at section 18-8-209(1), C.R.S. (2014), which states "[aluy sentence imposed following conviction of an offense under [certain enumerated sections] shall run consecutively ... with any sentence which the offender was serving at the time of the conduct prohibited by those sections").
{19 The plain language of the statute makes clear that if, at the time of sentencing, the offender has "any" sentence to serve, the trial court "shall" impose a consecutive sentence.
B. The Legislative Purpose
T 20 Even if we were to find the statutory language ambiguous, our conclusion would be the same because the legislative purpose supports our construction of section 18-3-208(1)(f). The provision resulted from a special session of the 1976 General Assembly, which focused on ways to curb inmate violence; the object sought to be attained is clearly deterrence of assaults on jail and prison staff, The People's suggested construction better facilitates this objective because that interpretation minimizes the potential for a concurrent sentence. Stated differently,~it maximizes the potential for additional time based on assaultive conduct against detention personnel while a defendant is in confinement or custody.
121 Highlighting this legislative purpose, another division of the court of appeals has noted that "[iJnterpreting the statute to limit the requirement of consecutive sentences to *626only those offenders who commit assaults while confined after a conviction, as defendant suggests, is inconsistent with the clearly expressed intent of the legislature to deter any assaults against peace officers and other workers within custodial settings by mandating additional punishment." Benavides, 222 P.3d at 394.
122 The majority distinguished this case from Benavides, reasoning that "[ulnlike the situation in Benavides, ... the sentencing court in this case did not order the assault sentence to be served consecutively to any sentence imposed on a charge for which defendant was confined when he committed the first assault." Digg, TI1L. This strikes us as a distinction without a difference. Granted, the procedural history of that case was different-the assault took place while the defendant was in custody awaiting the disposition of the other charges, to which the consecutive sentence was later appended. But the court's determination that "the sentencing court was required, pursuant to seetion 18-3-208(1)(£), to make his sentence for second degree assault consecutive to the sentences he received upon conviction for those other charges," see Benavides, 222 P.3d at 394, did not rest on the timing of his offenses. It rested on the statute's plain language and the legislative purpose behind it. Neither is temporal.5
C. Equal Protection
123 In addition to finding the statutory language ambiguous, the majority below deemed its interpretation necessary to avoid what it termed "serious equal protection concerns":6
[There would seem to be no rational basis for requiring consecutive sentencing based on the relative timing of the relevant sentencing proceedings, when one offense has no connection to the other and the timing could be the result of cireumstances utterly outside of the defendant's control or of decisions made to protect the defendant's legal rights.
Diaz, " 17.
124 We agree that any equal protection issue here would be resolved under rational basis review. However, we disagree that a rational basis is absent.
$25 "When a statute is subject to an equal protection challenge, the level of *627judicial serutiny varies with the type of classification utilized and the nature of the right affected." Romero, 912 P.2d at 66. One of three standards of review may apply: strict scrutiny, intermediate serutiny, or rational basis review. Id. A rational basis standard of review applies where, as here, no traditionally suspect class is present, no fundamental right is at issue, and no other classification warrants review under strict or intermediate serutiny.7 Pace Membership Warehouse v. Axelson, 938 P.2d 504, 506-07 (Colo.1997). Under this standard, the challenging party must prove beyond a reasonable doubt that the classification bears no rational relationship to a legitimate legislative purpose or government objective, or that the classification is unreasonable, arbitrary, or capricious. Id.; see also Romero, 912 P.2d at 66. "Simply because a statutory classification creates a harsh result in one instance does not mean that the statute fails to meet constitutionality requirements under the rational basis standard." Axelson, 988 P.2d at 507.
126 Here, as explained above, the legitimate legislative purpose and government objective of section 18-3-2083(1)(f) is to deter violence against prison guards. Consecutive sentencing is rationally related to-and promotes-this important objective. That any inmate will serve a full sentence for such an assault, regardless of when he or she is sentenced, has an important deterrent effect; a concurrent sentence, by contrast, would have almost no effect.
IV. Conclusion
T27 We hold that section 18-8-2083(1)(F) requires a consecutive sentence if, at the time of sentencing, the defendant is serving any other sentence. Therefore, we reverse the court of appeals and remand for further proceedings consistent with this opinion.
JUSTICE COATS concurs in the judgment only, and JUSTICE EID joins in the concurrence in the judgment only.. We cite and analyze the current version of section 18-3-203(1)(f). The provision has been amended since the first and second assaults, but the amendments do not relate to the issue before us.
. Diaz was convicted under section 18-3-203(1)(f). This is a class four felony with a presumptive range of two to six years in the department of corrections. §§ 18-3-203(2)(b) and 18-1.3-401(1)(a)(V)(A), C.R.S. (2014). Because the defendant was in custody at the time of the offense, his sentence was aggravated under section 18-1.3-401(8)(a)(IV), C.R.S. (2014). The resulting aggravated range was four to twelve years. In its Presentence Investigation Report, the Department of Probation recommended a sentence of between eight and twelve years, primarily based on the defendant's prior convictions for felony menacing and kidnapping. The court imposed ten years.
. To summarize, the key dates are as follows:
® August 11, 2009 (date of offense for first assault)
e October 22, 2009 (date of offense for second assault)
® December 1, 2010 (guilty verdict for second assault)
® January 24, 2011 (sentencing for second assault)
e January 25, 2011 (guilty verdict for first assault)
e February 9, 2011 (sentencing for first assault)
. At one point during the sentencing hearing, the court said: 'It says a sentence (indiscernible) shall be served in the Department and shall run consecutively with any sentences being served by the offender. I assume that means at the time of the offense." (Emphasis added.) The court, defense counsel, and prosecutor all stated that they thought the provision could be so construed. Later in the hearing, the court observed:
[The defendant argues for concurrent as opposed to consecutive sentencing. So I guess what I look at in part is why would the legislature put consecutive in 18-3-203(1)(f) and I guess I have to assume that the reason they would want the sentence to be consecutive, the legislature, is for the reasons stated by [the prosecutor], which is that so that it will pack some punch, I guess. Because if while you're in custody you assault somebody and you[r] sentencing is concurrent, in effect, there is no new or additional penalty for that assault.
Just before imposing sentence, the court added: "So, the legislature has indicated they want to treat those offenses differently in terms of both consecutive sentences and the mandatory Department of Corrections sentence."
. In support of its statutory interpretation to the contrary, the majority below references the audiotape of the House Judiciary Committee hearing on September 15, 1976. See Diaz, 112 n.1. But beyond noting the statute's obvious purpose-curbing inmate violence-it is inappropriate for us to delve into legislative history. See Smith, 230 P.3d at 1190. Even if such an inquiry were appropriate, it would be fruitless here. The legislative history of section 18-3-203(1)(F) is ambiguous and sheds no light upon its meaning. The provision was part of House Bill 768-1001. Contemporaneous records do not exist for some hearings relevant to the bill, and existing records are contradictory. The audiotape reveals, for instance, that during the hearing on September 15, 1976, Representative Sears proposed an amendment that any sentences run "consecutively," without saying consecutively to what. The chair questioned the need for the amendment but then quickly summarized what had been proposed, stating in relevant part: "[The sentence imposed ... shall be served consecutively with the sentence for which the person was originally confined." (Emphasis added.) The amendment passed without objection or discussion, even as to the disparity between the oral records made by the representative proposing the amendment and the chair before the vote. The official staff summary of what occurred states only: "Motion of Representative Sears that bill be amended on page 3, line 17, by adding the following sentence: 'A sentence imposed pursuant to this section shall be served consecutive to all other sentences being served by the offender." (Emphasis added.) The majority below observed that "[For some reason lost to history, the person who made a written record of action at the hearing recorded that amendment using language different from that actually spoken, language virtually identical to what ended up in the statute." Dicz, 112 n.1. Given the way in which the relevant language was quickly batted around, it may have been "lost to history"" because it was lost even in the moment the competing iterations materialized. We cannot be sure. We do know, however, that the language that ultimately became law did not contain the limiting language fleetingly referenced by the chair of this one House subcommittee.
. The Fourteenth Amendment to the United States Constitution provides that ""[nlo state shall «... deny to any person within its jurisdiction the equal protection of the laws." U.S. Const. amend. XIV, § 1. The right to equal protection also finds support in the due process clause of our state constitution. Indus. Claim Appeals Office v. Romero, 912 P.2d 62, 66 (Colo.1996) (citing Colo. Const. art. II, § 25).
. Strict scrutiny review applies where the statute in question discriminates against members of traditionally suspect classes, such as those based on race, or involves a fundamental constitutional right, such as the right afforded by the Fifth Amendment to the United States Constitution. Evans v. Romer, 854 P.2d 1270, 1275 (Colo. 1993). Courts will uphold laws subject to such review only if a compelling state interest supports them and the statute is narrowly drawn to achieve that interest by the least restrictive means. Id. Intermediate scrutiny requires a showing that the statute in question furthers "a sufficiently important governmental interest" in discriminating, for example, on the basis of gender. Id. at 1275-76.