*239OPINION
HUDSON, Justice.Appellant Mahdi Hassan Ali (“Mahdi”)1 shot and killed three men during a robbery of the Seward Market when he was 16 years old.2 Following a jury trial, he was convicted of three counts of murder that we affirmed on appeal. State v. Ali, 855 N.W.2d 235, 240 (Minn. 2014). He now challenges the district court’s imposition of three consecutive sentences of life imprisonment with the possibility of release after 30 years on each sentence. According to Mahdi, the rule announced in Miller v. Alabama, 567 U.S. 460, 132 S.Ct. 2455, 183 L.Ed.2d 407 (2012), and later clarified in Montgomery v. Louisiana, — U.S. -, 136 S.Ct. 718, 193 L.Ed.2d 599 (2016), should be extended to his case because his three consecutive sentences are, in the aggregate, the “functional equivalent” of life imprisonment without the possibility of release (LWOR). He also argues, for the first time, that his consecutive sentences violate his right to equal protection under the United States Constitution and the Minnesota Constitution. Finally, Mahdi argues that the district court abused its discretion when it sentenced him to three consecutive sentences because the sentences unfairly exaggerate the criminality of his conduct.
Because Miller and Montgomery involved the imposition of a single sentence of life imprisonment without the possibility of parole and the United States Supreme Court has not squarely addressed the issue of whether consecutive sentences should be viewed separately when conducting a proportionality analysis under the Eighth Amendment to the United States Constitution, we decline to extend the Miller/Montgomery rule to include Mahdi and other similarly situated juvenile offenders. Mahdi also forfeited his equal protection claim when he failed to raise the claim in the district court. In addition, our review of sentences received by other juvenile offenders who were convicted of murdering multiple, victims indicates that Mahdi’s three consecutive sentences do not unfairly exaggerate the criminality of his conduct. For these reasons, we affirm.
I.
Appellant Mahdi Hassan Ali was charged with the shooting deaths of three men during a robbery of the Seward Market in Minneapolis on January 6, 2010. Ali, 855 N.W.2d at 240. The State alleged the following events occurred. When Mahdi entered the Seward Market, Osman Elmi, an employee of the store, and Mohamed Warfa, a relative of Elmi’s, were sitting behind the store’s counter. Id. Mahdi thrust a gun into Elmi’s face and pulled Warfa to the ground. Id. When Anwar Mohammed, a store customer, walked through the front door, Mahdi shot him two times, including once in the head. Id. at 240-41. Mahdi’s accomplice yelled in Somali, “Don’t Kill” or “No Killing!” Id. at 241. After shooting Mohammed, Mahdi ran out of the store. Id. Shortly after, Mahdi returned and shot Warfa at least twice. Id. As Warfa’s body fell, it held open the front door of the store. Id. Mahdi’s accomplice jumped over Warfa and ran out the door of *240the store. Id. Mahdi chased-Elmi through the store. Id. A rack of snacks tipped over and spilled as the two men raced around a corner, before Mahdi shot Elmi three times in the back. Id. The store’s surveillance camera captured footage of the shootings. Id. Mahdi later told his cousin that he shot the three men because “they knew,” meaning they knew who he was. Id. at 248.
In September 2011, a jury found Mahdi guilty of three counts of first-degree felony murder while committing or attempting to commit aggravated robbery, one count of first-degree premeditated murder, and two counts of second-degree murder. Id. In October 2011, the district court sentenced him to two consecutive sentences of life with the possibility of release after 30 years for the felony murders of Mohammed and Warfa (Counts I and II), and a mandatory LWOR sentence for the first-degree premeditated murder of Elmi (Count III). Id. Mahdi filed a direct appeal, which we stayed to allow postconviction proceedings to proceed. Id. at 244, After the posteonviction court denied Mahdi’s request for relief, we consolidated his direct and postconviction appeals. Id.
In the consolidated appeal, we agreed that the mandatory sentence of LWOR was unconstitutional under Miller, 567 U.S. at 465, 132 S.Ct. 2455, but we rejected Mahdi’s argument that the district court’s discretionary imposition of two consecutive sentences of life imprisonment with the possibility of release after 30 years for Counts I and II violated Miller. Ali, 855 N.W.2d at 256-58. We also rejected Mahdi’s argument that the two consecutive sentences violated Article I, Section 5 of the Minnesota Constitution, which prohibits “cruel or unusual punishments.” Ali, 855 N.W.2d at 258. We explained that the two consecutive sentences were not “cruel” under Article I, Section 5, because the sentences were not “disproportionate considering the gravity of the offenses the jury found that he committed.” Ali, 855 N.W.2d at 259. We further explained that the two consecutive sentences were not “unusual” when compared to other offenders convicted of the same or similar offenses both inside and outside of Minnesota. Id. Ultimately, we affirmed the two consecutive sentences of life imprisonment with the possibility of release after 30 years (Counts I and II), but reversed the LWOR sentence (Count III) and remanded to the district court for resentencing on Count III, following a Miller hearing. Id. at 256, 258.
On remand, the State argued there was no need to hold a Miller hearing because the State had decided not to seek a LWOR sentence on Count III. Instead, the State “stipulated”3 that the district court could impose a third consecutive sentence of life imprisonment with the possibility of release after 30 years. In explaining the State’s position at the resentencing hearing, the prosecutor said, “[Gjiven that the Minnesota Supreme Court affirmed the consecutive imposition of essentially the three life terms, [Mahdi] will be over 100 years old before he is eligible for parole, and [the State] felt that judicial economy would be best served by foregoing a Miller hearing in this particular case.” The State also argued that the district court had previously received sufficient evidence about Mahdi’s past to decide whether a third consecutive sentence of life imprisonment with the possibility of release after 30 years was appropriate.
*241Mahdi argued that despite the State’s decision not to seek a LWOR sentence, the Eighth Amendment still required a Miller hearing because the imposition of three consecutive sentences of life imprisonment with the possibility of release after 30 years on each sentence (i.e., 90 years total) was the “functional equivalent” of a LWOR sentence. He also argued that a Miller hearing could not be held in his case without violating the separation of powers doctrine because the Legislature has not provided a framework for Miller hearings. Ultimately, Mahdi asked the district court to impose three concurrent sentences of life imprisonment with the possibility of release after a total of 30 years.
The district court determined that Mahdi’s argument regarding the necessity of a Miller hearing was “moot” because the State had agreed to a third sentence of life imprisonment with the possibility of release after 30 years to be served consecutively to the sentences on Counts I and II. The district court also concluded that the imposition of consecutive sentences, even if they could be considered the functional equivalent of a sentence of LWOR, was not the same as a mandatory LWOR sentence imposed for a single offense.
As for Mahdi’s motion for the imposition of concurrent sentences, the district court reasoned that it was bound by our previous decision in Ali, 855 N.W.2d at 235, which affirmed the two consecutive sentences of life imprisonment with the possibility of release after 30 years. The district court went on to state that “[e]ven if [it] had the discretion to impose concurrent sentences, it would not.” It reasoned that “[t]he criteria listed ... at the original sentencing hearing [were] still valid,” and that “[t]his was still a brutal, inexcusable murder of three innocent members of the community.” According to the district court, “[a] plethora of information regarding Defendant’s youthful age, personal background, and unique circumstances was presented to [the district] court prior to and during trial. All of this information was carefully considered in sentencing Counts I and II.” On January 6, 2016, the district court imposed a third sentence of life imprisonment with the possibility of release after 30 years, to be served consecutively with the sentences on the two other murder counts.
On January 25, 2016, the United States Supreme Court decided Montgomery, — U.S. -, 136 S.Ct. at 718. The Court clarified that Miller barred “life without parole ... for all but the rarest of juvenile offenders, those whose crimes reflect permanent incorrigibility.” Montgomery, — U.S. -, 136 S.Ct. at 734.
On April 5, 2016, Mahdi appealed from the district court’s January 6 sentencing order, asserting three arguments. First, he argues that the rule announced in Miller, and later clarified in Montgomery, should be extended to his case because his three consecutive sentences are, in the aggregate, the “functional equivalent” of LWOR. Second, he argues, for what he acknowledges is the first time on this appeal, that his consecutive sentences violate his right to equal protection under the Minnesota Constitution. Third, he argues that the district court abused its discretion in sentencing him to consecutive sentences because the resulting aggregate sentence unfairly “exaggerates the criminality” of his conduct. We consider each argument in turn.
II.
We first address Mahdi’s argument that we should extend the rule announced in Miller, and later clarified in Montgomery, to his case because his three consecutive sentences are, in the aggregate, the “functional equivalent” of LWOR. Mahdi *242contends that Montgomery made clear that “absent proof of permanent incorrigibility, a sentence violates the Eighth Amendment if it deprives a juvenile of a realistic possibility of release during the juvenile’s natural life expectancy.”4 He also observes that Miller “did not carve out any exception for aggregate sentencing.” Thus, according to Mahdi, the reasoning underlying the Miller/Montgomery rule applies with equal force when a district court imposes consecutive sentences of life imprisonment with the possibility of release that are, in the aggregate, the functional equivalent of a LWOR sentence.
The State contends,5 in part, that Mahdi’s argument is fundamentally flawed because it fails to acknowledge that consecutive sentences must be viewed separately under the Eighth Amendment. The State relies on O’Neil v. Vermont, in which the United States Supreme 'Court was asked to rule on whether consecutive sentences for 307 liquor-law infractions violated the Eighth Amendment’s prohibition against cruel and unusual punishment. 144 U.S. 323, 330-31, 12 S.Ct. 693, 36 L.Ed. 450 (1892). Although the Court ultimately concluded that it lacked jurisdiction to decide the question, id. at 334-35, 12 S.Ct. 693, it quoted the reasoning of the underlying state supreme court:
It would scarcely be competent for a person to assail the constitutionality of the statute prescribing a punishment for burglary, on the ground that he had committed so many burglaries that, if punishment for each were inflicted on him, he might be kept in prison for life. The mere fact that cumulative punishments may be imposed for distinct of-fences in the same prosecution is not material upon this question. If the penalty were unreasonably severe for a single offence, the constitutional question might be urged; but here the unreasonableness is only in the number of of-fences which the respondent has committed.
Id. at 331, 12 S.Ct. 693 (emphasis added) (quoting State v. O’Neil, 58 Vt. 140, 2 A. 586, 593 (1886)).
The State acknowledges that the above-quoted language from the United States Supreme Court’s opinion is dictum. Nevertheless, it contends that we should follow the dictum of O’Neil because it is well reasoned, as evidenced by the many federal and state courts that have accepted its logic. See Pearson v. Ramos, 237 F.3d 881, 886 (7th Cir. 2001) (“[I]t is wrong to treat stacked sanctions as a single sanction. To do so produces the ridiculous consequence of enabling a prisoner, simply by recidivat-ing, to generate a colorable' Eighth Amendment claim.”); Hawkins v. Hargett, 200 F.3d 1279, 1285 n.5 (10th Cir. 1999) *243(explaining that the “Eighth Amendment analysis focuses on the sentence imposed for each specific crime, not on the cumulative sentence”); United States v. Aiello, 864 F.2d 257, 265 (2d Cir. 1988) (same); State v. Berger, 212 Ariz. 473, 134 P.3d 378, 380, 384 (2006) (affirming a 200-year sentence for multiple acts of child pornography because “[a] defendant has no constitutional right to concurrent sentences for two separate crimes” (quoting State v. Jonas, 164 Ariz. 242, 792 P.2d 705, 712 (1990))); State v. Hairston, 118 Ohio St.3d 289, 888 N.E.2d 1073, 1077-79 (2008) (analyzing each sentence for each crime separately and rejecting the argument that an aggregate prison term of 134 years for multiple crimes violated the Eighth Amendment); State v. Buchhold, 727 N.W.2d 816, 823-26 (S.D. 2007) (holding that consecutive sentences for 11 sexual assault counts that amounted to a “de fac-to” life sentence of 175 years in prison did not violate the Eighth Amendment). According to the State, “[a]ll of these cases stand for the unremarkable proposition that it is constitutionally permissible to punish a person who commits two, three, four or even more crimes (including murder) more severely than a person who commits a single crime.” See Ewing v. California, 538 U.S. 11, 25, 123 S.Ct. 1179, 155 L.Ed.2d 108 (2003) (“Recidivism has long been recognized as a legitimate basis for increased punishment”).
Whether a criminal sentence violates the Eighth Amendment is a question of law that we review de novo. State v. Gutierrez, 667 N.W.2d 426, 438 (Minn. 2003). The Eighth Amendment to the United States Constitution prohibits “cruel and unusual punishments.” U.S. Const, amend. VIII. The United States Supreme Court has recognized that, for the most part, its Eighth Amendment “precedents consider punishments challenged not as inherently barbaric but as disproportionate to the crime.” Graham v. Florida, 560 U.S. 48, 59, 130 S.Ct. 2011, 176 L.Ed.2d 825 (2010). We have said that “[t]he concept of proportionality is central to the Eighth Amendment.” State v. Juarez, 837 N.W.2d 478, 480 (Minn. 2013) (quoting Graham, 560 U.S. at 59, 130 S.Ct. 2011).
In recent years, the United States Supreme Court has decided a line of cases acknowledging that fundamental differences between juveniles and adults affect the proportionality analysis under the Eighth Amendment, and therefore most juveniles are categorically less deserving of the harshest punishments. However, none of these cases have involved challenges to consecutive sentences.
For example, in Roper v. Simmons, a defendant was convicted of and sentenced to death for a single murder committed when he was 17 years old. 543 U.S. 551, 557, 125 S.Ct. 1183, 161 L.Ed.2d 1 (2005). After outlining three general ways in which juvenile offenders differ from their adult counterparts, the Court adopted a categorical ban on death sentences for juveniles. Id. at 568-71, 578, 125 S.Ct. 1183. Five years later, in Graham, a defendant was sentenced to life imprisonment without the possibility of parole for an armed burglary committed when the defendant was 16 years old. 560 U.S. at 53, 57, 130 S.Ct. 2011. Reaffirming Roper, the Court held that a juvenile “may not be sentenced to life without parole for a nonhomieide crime.” Id. at 74-75, 130 S.Ct. 2011 (emphasis added).
More recently, in Miller, the Court considered an Eighth Amendment challenge in a consolidated appeal involving two 14-year-old offenders. 567 U.S. at 465, 132 S.Ct. 2455. Both defendants received mandatory sentences of life imprisonment without the possibility of parole based on their single-murder convictions. Id. at 465-*24469, 132 S.Ct. 2455. The Court ultimately held that the mandatory imposition of life imprisonment without the possibility of parole on a juvenile homicide offender violates the Eighth Amendment. Id. at 479, 132 S.Ct. 2455. The Court stated that “a judge or jury must have the opportunity to consider mitigating circumstances before imposing the harshest possible penalty for juveniles.” Id. at 489, 132 S.Ct. 2455.
Finally, in Montgomery, the Court considered an Eighth Amendment challenge to a mandatory sentence of life imprisonment without the possibility of parole that was imposed nearly 50 years before the Court decided Miller. Montgomery, — U.S. at -, 136 S.Ct. at 726. The defendant in Montgomery was also convicted of a single murder. Id. at -, 136 S.Ct. at 725. The Court clarified that Miller “did more than require a sentencer to consider a juvenile offender’s youth before imposing life without parole; it established that the penological justifications for life without parole collapse in light of ‘the distinctive attributes of youth.’ ” Id. at -, 136 S.Ct. at 734 (quoting Miller, 567 U.S. at 472, 132 S.Ct. 2455). The Court stated that, “[e]ven if a court considers a child’s age before sentencing him or her to a lifetime in prison, that sentence still violates the Eighth Amendment for a child whose crime reflects ‘unfortunate yet transient immaturity.’ ” Id. at -, 136 S.Ct. at 734 (quoting Miller, 567 U.S. at 479-80, 132 S.Ct. 2455). According to Montgomery, Miller determined that life imprisonment without the possibility of parole is unconstitutional for all children except for “the rare juvenile offender whose crime reflects irreparable corruption” or “permanent incorrigibility.” Id. at -, 136 S.Ct. at 734 (quoting Miller, 567 U.S. at 479-80, 132 S.Ct. 2455). Therefore, the Court held that Miller applied retroactively to juvenile homicide offenders whose convictions were final when Miller was decided because Miller created a new substantive constitutional rule that sentencing a juvenile homicide offender to life imprisonment without the possibility of parole was excessive under the Eighth Amendment for all but “the rare juvenile offender whose crime reflects irreparable corruption.” Montgomery, — U.S. at -, 136 S.Ct. at 734 (quoting Miller, 567 U.S. at 479-80, 132 S.Ct. 2455).
Because Roper, Graham, Miller, and Montgomery did not involve challenges to consecutive sentences, the Court has not squarely addressed the issue presented in this case: whether the Miller/Montgomery rule should be extended to cases in which a juvenile homicide offender receives consecutive sentences of life imprisonment with the possibility of release that the juvenile contends are, in the aggregate, the “functional equivalent” of LWOR. In addition, the Court has not revisited the more general issue of whether consecutive sentences should be viewed separately when conducting a proportionality analysis under the Eighth Amendment.
A number of other courts have, however, addressed Eighth Amendment challenges that were based on arguments of functional equivalency. These cases can be divided into two general categories: cases involving a lengthy term-of-years sentence imposed for a single crime, see, e.g., State v. Ragland, 836 N.W.2d 107, 119-22 (Iowa 2013) (involving a commuted life sentence with no possibility of parole for 60 years imposed for a single murder committed by a juvenile), and cases involving a series of consecutive sentences for multiple crimes, see, e.g., Hawkins, 200 F.3d at 1280 (addressing consecutive sentences totaling 100 years for a juvenile who was convicted of multiple offenses, including home burglary, forcible sodomy, rape, and robbery with a dangerous weapon). Mahdi’s case falls within the second category.
*245In the second category of cases, every state supreme court and federal circuit court that has acknowledged the Court’s dictum in O’Neil has rejected an Eighth Amendment challenge to consecutive sentences.6 See, e.g., Hawkins, 200 F.3d at 1285 & n.5 (affirming the juvenile’s consecutive sentences, which totaled 100 years, explaining that the “Eighth Amendment analysis focuses on the sentence imposed for each specific crime, not on the cumulative sentence for multiple crimes”); Aiello, 864 F.2d at 265 (affirming the defendant’s consecutive sentences, which totaled 140 years, based on the dictum in O’Neil); Close v. People, 48 P.3d 528, 528, 538-40 (Colo. 2002) (affirming the juvenile’s consecutive sentences, which totaled 60 years, after discussing the dictum in O’Neil); Hairston, 888 N.E.2d at 1078 (affirming the defendant’s consecutive sentences, which totaled 134 years, after explaining that under the Eighth Amendment, “proportionality review should focus on individual sentences rather than on the cumulative impact of multiple sentences imposed consecutively”); Buchhold, 727 N.W.2d at 823-26 (affirming the defendant’s consecutive sentences, which totaled 175 years, after discussing the dictum in O’Neil and the numerous courts that had accepted its logic); cf. Pearson, 237 F.3d at 886 (affirming the defendant’s consecutive prison-discipline sanctions after discussing the dictum in O’Neil).
In contrast, when courts have failed to acknowledge the Court’s dictum in O’Neil, they have split on the issue of whether the Miller/Montgomery rule applies to consecutive sentences that are, in the aggregate, the “functional equivalent” of a life imprisonment without the possibility of parole sentence. Compare Starks v. Easterling, 659 Fed.Appx. 277, 280-81 (6th Cir. 2016) (unpublished) (affirming an aggregate sentence of 62 years in prison before any possibility of release because “the Supreme Court has not yet explicitly held that the Eighth Amendment extends to juvenile sentences that are the functional equivalent of life” and “it is not our role to predict future outcomes”), and Hobbs v. Turner, 2014 Ark. 19, 431 S.W.3d 283, 285, 289 (2014) (holding that an aggregate term of 55 years in prison was constitutional under Miller because Miller applies to only mandatory sentences of life imprisonment without the possibility of parole), with McKinley v. Butler, 809 F.3d 908, 909-11 (7th Cir. 2016) (extending Miller to two consecutive 50-year terms the juvenile offender received for convictions that involved the murder of one victim), State v. Zuber, 227 N.J. 422, 152 A.3d 197, 203, 215 (2017) (extending Miller to consecutive sentences that were, in the aggregate, the functional equivalent of life imprisonment without the possibility of parole when neither defendant would be eligible for parole for at least 55 years), and Bear Cloud v. State, 334 P.3d 132, 136, 141-42 (Wyo. 2014) (concluding that the imposition of a life sentence with the possibility of parole after 25 years for a single felony murder conviction to be served consecutively with a sentence of 20-25 years for a burglary conviction implicated Miller because the juvenile offender would not be eligible for parole until he was 61 years old).
We acknowledge that, as the United States Supreme Court has explained, fun*246damental differences between juveniles and adults affect the proportionality analysis under the Eighth Amendment. But the Court has not held that the Miller/Montgomery rule applies to sentences other than life imprisonment without the possibility of parole. Moreover, the Court has not squarely addressed the issue of whether consecutive sentences should be viewed separately when conducting a proportionality analysis under the Eighth Amendment because the Court’s discussion of the issue in O'Neil was dictum.7 Admittedly, we have elected to follow well-reasoned Supreme Court dictum in the past. See, e.g., State v. Craig, 826 N.W.2d 789, 793 (Minn. 2013). But here, we simply hold that absent further guidance from the Court, we will not extend the Miller/Montgomery rule to include Mahdi and other similarly situated juvenile offenders who are being sentenced for multiple crimes, especially when the Court has not held that the Miller/Montgomery rule applies to sentences other than life imprisonment without the possibility of parole and the issue of whether consecutive sentences should be viewed separately when conducting a proportionality analysis under the Eighth Amendment remains an open question.8
III.
We- next address Mahdi’s equal protection argument. For the first time on appeal, as Mahdi himself acknowledges, he contends that the district court denied, him equal protection under the United States Constitution and the Minnesota Constitution. According to Mahdi, the court sentenced him to the functional equivalent of a LWOR sentence without holding a Miller hearing, thus treating him differently from the petitioners in Miller, even though they were similarly-situated juvenile offenders. In response, the State emphasizes that Mahdi’s equal protection claim should not be considered for the first time on appeal. We agree with the State.
We have repeatedly stated that “[t]he law is clear in Minnesota that the constitutionality of a statute cannot be challenged for the first time on appeal.” State v. Moore, 846 N.W.2d 83, 87 (Minn. 2014) (quoting State v. Engholm, 290 N.W.2d 780, 784 (Minn. 1980)). Given this clear rule, we do not reach the merits of this issue and consider it to be forfeited.
IV.
Mahdi’s last contention is that, even if the three consecutive sentences are constitutional, the district court abused its discretion on remand because sentencing Mahdi, a juvenile, to a lengthy aggregate sentence based on multiple victims unfairly exaggerates the criminality of his conduct. Mahdi argues that he is less culpable because his actions were the result of his youth and its attendant characteristics.
*247We review a district court’s decision to impose consecutive sentences for an abuse of discretion. State v. McLaughlin, 725 N.W.2d 703, 715 (Minn. 2007). “Although the abuse of discretion standard is exacting, it is not a limitless grant of power to the trial court.” State v. Warren, 592 N.W.2d 440, 451 (Minn. 1999). We will interfere with the district court’s sentencing discretion only when “the sentence is disproportionate to the offense or unfairly exaggerates the criminality of the defendant’s conduct.” McLaughlin, 725 N.W.2d at 715 (quoting State v. Sanchez-Diaz, 683 N.W.2d 824, 837 (Minn. 2004)) (internal quotation marks omitted). And we “look to past sentences received by other offenders in determining whether the distinct court abused its discretion.” State v. Fardan, 773 N.W.2d 303, 322 (Minn. 2009).
As we discussed in his previous case before this court, Mahdi’s sentences are similar to those received by other juvenile offenders convicted of multiple murders. Ali, 855 N.W.2d at 259-60; see McLaughlin, 725 N.W.2d at 715-16 (upholding the imposition of two consecutive life sentences for an offender who killed two of his classmates when he was 15 years old, and noting that “youth” was a factor in numerous cases in which we had upheld comparable sentences, especially those involving “particularly callous murders”); State v. Ouk, 516 N.W.2d 180, 184, 186 (Minn. 1994) (holding that the district court did not abuse its discretion in imposing two life sentences for a juvenile offender’s two first-degree murder convictions and two 180-month sentences for his two attempted first-degree murder convictions, all sentences served consecutively); State v. Brom, 463 N.W.2d 758, 765 (Minn. 1990) (holding that the district court did not abuse its discretion in sentencing a juvenile defendant to three consecutive life sentences and one concurrent life sentence for four first-degree murder convictions). Based on our review of the sentences received by other juvenile offenders who were convicted of murdering multiple victims, we conclude that the three consecutive sentences are not disproportionate to Mahdi’s offenses and do not unfairly exaggerate the criminality of his conduct.
To the extent that Mahdi is arguing that the district court abused its discretion when it resentenced him by not providing an opportunity for Mahdi’s counsel to advocate, with expert testimony, how Mahdi’s youth should lessen his culpability, Mahdi is essentially claiming that the district court abused its discretion by failing to hold a Miller hearing before imposing a third consecutive life sentence. Because we hold that Miller and Montgomery do not apply here, this argument is without merit.9
Moreover, in the district court’s ■ resen-tencing order, the district court noted that it had considered “[a] plethora of information regarding [Mahdi’s] youthful age, personal background, and unique circumstances” at the first sentencing hearing. At the resentencing hearing, the court also offered both parties opportunities to speak, and Mahdi’s counsel did not request to provide additional witness testimony or evidence.
*248Accordingly, we conclude that the district court did not abuse its discretion on remand when it imposed a third consecutive life sentence with the possibility of release after 30 years because the sentences that Mahdi received did not unfairly exaggerate the criminality of his conduct in this triple homicide case.
For the foregoing reasons, we affirm the district court’s sentencing decision.
. We referred to appellant by his first name in his previous appeal, State v. Ali, 855 N.W.2d 235, 240 n.1 (Minn. 2014), because several of the men involved in the case had the last name Ali. To avoid confusion, we do the same here.
. Before his trial, Mahdi claimed he was 15 years old at the time of the murders. After a 3-day age-determination hearing, however, the district court found that the evidence established that Mahdi was at least 16 years old when the murders were committed, State v. Ali, 855 N.W.2d 235, 243 (Minn. 2014).
. At the resentencing hearing, Mahdi's counsel denied having agreed to the State’s "stipulation” and asked to preserve his arguments regarding resentencing and the request for a Miller hearing for appeal.
. Mahdi also asserts that Montgomery “dictates that [his] aggregate sentence be found to be cruel or ... unusual under the state constitution.” He, however, fails to articulate how Montgomery impacts our previous holding in Ali, 855 N.W.2d at 259, that Mahdi’s consecutive sentences were neither cruel nor unusual under Article I, Section 5 of the Minnesota Constitution. As discussed in more detail below, the Court’s decision in Montgomery interpreted the Eighth Amendment in a case involving a single sentence of life imprisonment without the possibility of parole and the Court’s decision in O'Neil v. Vermont, 144 U.S. 323, 331, 12 S.Ct. 693, 36 L.Ed. 450 (1892), suggests that consecutive sentences should be treated separately' for Eighth Amendment purposes. We, therefore, conclude that Montgomery does not dictate that Mahdi’s three consecutive sentences are cruel or unusual under Article I, Section 5.
., On October 26, 2016, the State moved to file a substitute brief under Minn. R. Civ. App. P. 127 to correct several typographical errors in its brief filed August 29, 2016. Mahdi did not oppose the motion. We grant the State’s motion.
. The dissent contends that in the absence of any opinion by a state supreme court or federal circuit court discussing the interplay between O’Neil and Montgomery, we should extend Montgomery to consecutive sentences. We decline to do so because the discussion from O’Neil is the only explanation from the United States Supreme Court we have on the interplay between the Eighth Amendment and consecutive sentences. In light of O’Neil and the lack of authority from other courts, we take a cautious approach today.
.. The dissent contends that the dictum in O'Neil "runs headlong into the essence of Miller and Montgomery." We disagree. O'Neil addresses the scope of a court’s proportionality review, explaining that consecutive sentences should be considered separately, whereas Miller and Montgomery address the nature of a court’s proportionality review in cases involving juvenile offenders, explaining that the review must include a consideration of whether the juvenile’s crime reflected unfortunate yet transient immaturity. Because O'Neil addresses a separate and distinct Eighth Amendment question, it does not "run headlong into the essence of Miller and Montgomery."
. Accordingly, we also note that Montgomery does not impact our holding in State v. Williams, 862 N.W.2d 701, 703-04 (Minn. 2015) (declining to extend Miller to a district court’s discretionary imposition of consecutive sentences resulting in an aggregate sentence of at least 74 years in prison).
, In Mahdi's reply brief, he argues for the first time that the district court's failure to hold a Miller hearing is a structural error that "necessitates vacating the sentence.” Under the Minnesota Rules of Civil Appellate Procedure, the reply brief is confined to new matter raised in the brief of the respondent. Minn. R. Civ. App. P. 128.02, subd. 3. Because the State did not raise this matter in its brief, it was not a proper subject matter for Mahdi’s reply brief. "[W]e have declined to consider issues raised for the first time in a reply brief, particularly when the theory was not raised at the district court level.” Moorhead Econ. Dev. Auth. v. Anda, 789 N.W.2d 860, 887 (Minn. 2010).