BLACKWELL, Justice.

In July 1998, Jamel Humphrey negotiated a plea agreement with the State, entered a plea of guilty but mentally ill, was convicted of murder upon his plea, and was sentenced to a term of imprisonment for life with the provision that he would be eligible for parole, but only after he served 25 years of his sentence. Almost sixteen years later, Humphrey filed a motion to vacate his sentence, alleging that the sentence is void because murder is punishable only by death, imprisonment for life without any possibility of parole ever, or imprisonment for life with the possibility of parole at the earliest point permitted by law, which would have been, in Humphrey's case, after fourteen years.1 The trial court denied his motion, and Humphrey appeals. For the reasons that follow, we reverse the judgment of the trial court and remand the case with direction.

To begin, we agree with Humphrey that the law only authorized the trial court to sentence him to death, imprisonment for life without any possibility of parole ever, or imprisonment for life with the possibility of parole as soon as permitted by law. See OCGA § 16-5-1(e)(1). The applicable law offered the trial court no other sentencing options. It is true that Humphrey consented to his sentence, including the provision that he would be ineligible for parole for the first 25 years of that sentence. But when a court imposes a criminal punishment that the law does not allow, the sentence is not just an error, it is void. See Crumbley v. State, 261 Ga. 610, 611(1), 409 S.E.2d 517 (1991) ("A sentence is void if the court imposes punishment that the law does not allow." (Citation omitted.)). And as we have indicated in a number of cases, the consent of the parties cannot validate a void sentence. See, e.g., Moore v. State, 293 Ga. 705, 706(1), 749 S.E.2d 660 (2013) ("[A] defendant who knowingly enters into a plea agreement and accepts the benefit of that bargain does not waive or `bargain away' the right to challenge an illegal and void sentence." (Citations omitted.)); Bell v. State, 294 Ga. 5, 8(2), 749 S.E.2d 672 (2013) ("A defendant who knowingly enters into a plea agreement does not waive the right to challenge an illegal and void sentence." (Citation omitted.)); von Thomas v. State, 293 Ga. 569, 573(2), 748 S.E.2d 446 (2013) ("[A] sentence which is not allowed by law is void, and its illegality may not be waived." (Citations, punctuation, and emphasis omitted.)); Nazario v. State, 293 Ga. 480, 487(2)(c), 746 S.E.2d 109 (2013) ("Void convictions and illegal sentences have never been subject to general waiver rules.").

These principles seem especially sound when applied to a sentence that purports to limit eligibility for parole in a way that is not authorized by statutory law. By imposing such a sentence, a court intrudes upon the constitutional prerogative of the State Board of Pardons and Paroles to extend clemency to persons under sentence. See Ga. Const. of 1983, Art. IV, Sec. II, Par. II(a) ("[T]he State Board of Pardons and Paroles shall be vested with the power of executive clemency, including the powers to grant reprieves, pardons, and paroles...."). Although the Constitution permits the General Assembly by statute to limit this prerogative in certain respects, see Ga. Const. of 1983, Art. IV, Sec. II, Par. II(b-c), the Constitution gives the courts no such authority. For that reason, a judicial incursion upon the constitutional prerogative of the Board "violates the constitutional provision regarding the separation of powers." Terry v. Hamrick, 284 Ga. 24, 25(2), 663 S.E.2d 256 (2008). And whatever the prosecuting attorneys and defendant in a criminal case might agree to, they cannot simply by agreement confer upon the judicial branch an extraconstitutional power to limit the constitutional prerogatives of another branch of the government. See Perez v. State, 254 Ga.App. 872, 873(1), 564 S.E.2d 208 (2002) ("The authority to grant parole or other relief from the sentence imposed by the trial court rests with the State Board of Pardons & Paroles, not the district attorney's office." (Citation omitted.)). To the extent that we held otherwise in Baker v. State, 284 Ga. 280, 281(2), 663 S.E.2d 261 (2008), we overrule that decision.

The sentence that the trial court imposed in this case is void to the extent that it purports to limit the power of the Board to parole Humphrey as soon as the statutory law permits. That provision of the sentence — but only that provision — must be vacated. See Bell, 294 Ga. at 8(2), 749 S.E.2d 672 ("When a defendant is sentenced in a murder case to life imprisonment plus probation, only the portion of the sentence imposing probation is invalid." (Citation omitted.)). Accordingly, we reverse the denial of the motion to vacate the sentence, and we remand for the trial court to vacate the provision of the sentence that purports to limit Humphrey's eligibility for parole.2 See Terry, 284 Ga. at 25(2), 663 S.E.2d 256; Brown v. State, 246 Ga. 251, 253(5), 271 S.E.2d 163 (1980).

Judgment reversed and case remanded with direction.

All the Justices concur.