*387(1) life, if the individual committed the offense when younger than 18 years of age; or
(2) life without parole, if the individual committed the offense when 18 years of age or older.23
A review of the statutory text makes clear that the language relating to age does not prescribe an element of a capital murder offense but is a matter relating to punishment. The age of the offender comes into play only after he has been "adjudged guilty of a capital felony," and the statute says that such an offender shall be "punished by" a certain amount depending on his age at the time of the offense.24 These quoted phrases signify a punishment matter.25 In addition, the statute appears in the subchapter titled "Ordinary Felony Punishments."26
The remaining question is whether age is a punishment enhancer, and so, an element from a constitutional perspective that has to be proven by the State beyond a reasonable doubt.27 Appellant contends that it is, but we disagree. The United States Supreme Court has held that the State may "choose[ ] to recognize a factor that mitigates the degree of criminality or punishment" without being required "to prove its nonexistence."28 We have followed this holding, concluding that the United States Constitution does not require the State to bear the burden of proof on an issue that, if answered affirmatively, would reduce, rather than increase, the sentence.29 If being under age 18 is a fact that reduces the otherwise applicable sentence, then a statute can place the burden of proof on the defendant to show that fact without violating the Constitution.
If subdivisions (1) and (2) of § 12.31(a) are viewed in isolation, then we are confronted with two prescribed punishments, with the age of 18 or older attached to the higher punishment and with being under age 18 attached to the lower punishment. Both subdivisions cannot prescribe elements the State must prove because that would lead to the absurd result of placing a defendant's punishment in legal limbo, where, as in the present case, there is no evidence of the defendant's age. In isolation, the first subdivision could be viewed *388as a punishment aggravator (that the State must prove) while the second subdivision could be viewed as a punishment mitigator (with a burden of production or proof on the defense). Such a construction would cause these subdivisions to conflict.
But there is more to the statute than these two subdivisions. As quoted above, § 12.31(a) says that if the State seeks the death penalty, then the maximum punishment is death and the minimum punishment is life without parole. Under the statutory language, a different allocation of punishments based on age occurs only when the State chooses not to seek the maximum punishment of death.
To fully appreciate the significance of this language, we must also consider the provision found at § 8.07(c): "No person may, in any case, be punished by death for an offense committed while the person was younger than 18 years."30 The Penal Code makes § 8.07(c) a defensive issue. The provision is found in Chapter 8, which is titled "General Defenses to Criminal Responsibility,"31 and it is unambiguously worded as a punishment exemption. The Penal Code does not, however, label this exemption as an affirmative defense, nor does it include in the exemption punishment language reminiscent of an affirmative defense.32 Because the exemption in § 8.07(c) is not plainly labeled as an affirmative defense, it should be treated like a defense,33 which means the defendant has the burden to produce evidence supporting the defense,34 and the State has the burden, once that is done, to disprove the defense beyond a reasonable doubt.35 Consequently, § 8.07(c) prescribes a defensive issue with respect to the punishment of death, and the defendant logically carries the burden of producing some evidence that he committed the offense while he was younger than age 18. If he produces such evidence, the State must then prove beyond a reasonable doubt that the defendant was in fact 18 years old or older.
The interaction between §§ 8.07(c) and 12.31(a) supports a conclusion that the status of being under age 18 is a defensive issue whenever that status is implicated in a capital murder prosecution. If being under age 18 is a defensive issue to the death penalty as a punishment, then logically, it would also be a defensive issue as to the lesser punishment of life without parole. The idea is that being under age 18 makes one less culpable; it would makes no sense to make it more difficult to show the age exemption when the punishment exposure (death) is greater.
In addition, the placement and language of § 12.31 suggest that the statute was not intended to create an "age 18 or older" enhancing factor. The statute's placement in Subchapter C, titled, "Ordinary *389Felony Punishments" carries some suggestion that it does not contain punishment enhancements. Moreover, of the four other Penal Code sections in that subchapter, only the one relating to state jail felonies appears to contain punishment enhancements,36 and the enhancing provisions are prefaced by language requiring proof: "if it is shown on the trial of the offense that ...."37 This type of language is strongly associated with punishment enhancements38 but is missing from § 12.31. This is a further indication that § 12.31 should not be read in isolation but should be read in conjunction with § 8.07(c) to determine what role the age issue plays in arriving at the punishment for a capital felony. Consequently, the language of § 12.31 creates a defensive issue of being under age 18 rather than a punishment enhancing issue of being 18 years of age or older.
Because the age issue in § 12.31 is a defensive issue, Appellant had the burden to produce some evidence that he was under age 18 at the time of the offense. Because the record is devoid of any such evidence, Appellant's sufficiency claim necessarily fails.
C. Waiver
In Appellant's final ground he states:
Even if defendants bear the burden to prove when they were born, the court of appeals erred in affirming the instant judgment because the trial court never secured an express waiver from Appellant, admission from Appellant, or finding of fact that Appellant was indeed over the age of eighteen [18] on October 22, 2014.
Appellant argues that the issue of his age was at least a Marin39 category two right, meaning that it was (at most) waivable only. He further contends that he did not expressly waive such a right and is entitled to a remand for a new punishment hearing to litigate the age issue before a jury. He does not explain exactly which right he is referring to.
If Appellant is referring to his right under Miller not to be subject to a mandatory life sentence for a crime committed while under age 18, Appellant is correct that it is at least a waivable-only right, but as we have explained, he has failed to make the claim that was made in Miller . And as a matter in the nature of an affirmative defense, it was Appellant's burden to produce evidence and to prove that he was under age eighteen at the time of the offense. He has not done this.
Even assuming, without deciding, that Appellant has a right to develop a Miller claim, that does not mean he has a right to do so in any forum he chooses. Nothing in this record suggests that Appellant has a valid Miller claim, and he did not, at the trial level, request an opportunity to litigate such a claim. Under those circumstances, the trial court cannot be faulted for failing to litigate a Miller claim, and, as we have explained earlier, we have no basis for remanding to address such a claim.
If Appellant is referring to his due process right to legally sufficient evidence with respect to the statutory defensive issue, he may be correct that it is a non-forfeitable right, but a sufficiency claim does not involve a right to a remand for the purpose of taking evidence on the challenged issue; either the evidence is sufficient *390or it is not. As we have explained earlier, because he had the burden of producing evidence to support his defense and he has not done so, his sufficiency claim fails.
Finally, if Appellant is referring to his right to submit a statutory defensive issue regarding his age to a trier of fact, that claim is a forfeitable claim.40
We affirm the judgment of the court of appeals.