delivered the opinion of the Court.
The question presented in this case is whether the application of a Texas statute, which was passed after respondent’s crime and which allowed the reformation of an improper jury verdict in respondent’s case, violates the Ex Post Facto Clause of Art. I, § 10. We hold that it does not.
Respondent Carroll Youngblood was convicted in a Texas court of aggravated sexual abuse. The jury imposed punishment of life imprisonment and a fine of $10,000. After his conviction and sentence were affirmed by the Texas Court of Criminal Appeals, Youngblood applied for a writ of habeas corpus in the State District Court. He argued that the Texas Code of Criminal Procedure did not authorize a fine in addition to a term of imprisonment for his offense, and, thus, under the decision of the Court of Criminal Appeals in Bogany v. State, 661 S. W. 2d 957 (1983), the judgment and sentence were void, and he was entitled to a new trial.1 In April 1985, the District Court, feeling bound by Bogany, recommended that the writ be granted.
Before the habeas application was considered by the Texas Court of Criminal Appeals, which has the exclusive power under Texas law to grant writs of habeas corpus, see Tex. Code Crim. Proc. Ann., Art. 11.07 (Vernon 1977 and Supp. 1990), a new Texas statute designed to modify the Bogany *40decision became effective. Article 37.10(b), as of June 11, 1985, allows an appellate court to reform an improper verdict that assesses a punishment not authorized by law. Tex. Code Crim. Proc. Ann., Art. 37.10(b) (Vernon Supp. 1990); see Ex parte Johnson, 697 S. W. 2d 605 (Tex. Crim. App. 1985). Relying on that statute, the Court of Criminal Appeals reformed the verdict in Youngblood’s case by ordering deletion of the $10,000 fine and denied his request for a new trial.
Youngblood then sought a writ of habeas corpus from the United States District Court for the Eastern District of Texas, arguing that the retroactive application of Art. 37.10(b) violated the Ex Post Facto Clause of Art. I, § 10, of the Federal Constitution. The District Court concluded that since Youngblood’s “punishment . . . was not increased (but actually decreased), and the elements of the offense or the ultimate facts necessary to establish guilt were not changed,” there was no ex post facto violation. App. to Pet. for Cert. C-6.
The Court of Appeals reversed. Youngblood v. Lynaugh, 882 F. 2d 956 (CA5 1989). It relied on the statement in this Court’s decision in Thompson v. Utah, 170 U. S. 343 (1898), that retroactive procedural statutes violate the Ex Post Facto Clause unless they ‘“leave untouched all the substantial-protections with which existing law surrounds the person accused of crime,’” Lynaugh, supra, at 959 (quoting 170 U. S., at 352). It held that Youngblood’s right to a new trial under the Bogany decision was such a “substantial protection,” and therefore ordered that a writ of habeas corpus be issued. We granted certiorari. 493 U. S. 1001 (1989).
Because respondent is before us on collateral review, we are faced with a threshold question whether the relief sought by Youngblood would constitute a “new rule,” which would not apply retroactively under our decisions in Teague v. Lane, 489 U. S. 288 (1989), and Butler v. McKellar, 494 U. S. 407 (1990). Generally speaking, “[rjetroactivity is *41properly treated as a threshold question, for, once a new rule is applied to the defendant in the case announcing the rule, evenhanded justice requires that it be applied retroactively to all who are similarly situated.” Teague, supra, at 300. The State of Texas, however, did not address retroactivity in its petition for certiorari or its briefs on the merits, and when asked about the issue at oral argument, counsel answered that the State had chosen not to rely on Teague. Tr. of Oral Arg. 4-5. Although the Teague rule is grounded in important considerations of federal-state relations, we think it is not “jurisdictional” in the sense that this Court, despite a limited grant of certiorari, must raise and decide the issue sua sponte. Cf. Patsy v. Board of Regents of Fla., 457 U. S. 496, 515, n. 19 (1982) (Eleventh Amendment defense need not be raised and decided by the Court on its own motion). We granted certiorari to consider the merits of respondent’s ex post facto claim, and we proceed to do so.
Although the Latin phrase “ex post facto” literally encompasses any law passed “after the fact,” it has long been recognized by this Court that the constitutional prohibition on ex post facto laws applies only to penal statutes which disadvantage the offender affected by them. Calder v. Bull, 3 Dall. 386, 390-392 (1798) (opinion of Chase, J.); id., at 396 (opinion of Paterson, J.); id., at 400 (opinion of Iredell, J.). See Miller v. Florida, 482 U. S. 423, 430 (1987).2 As early opinions in this Court explained, “ex post facto law” was a term of art with an established meaning at the time of the framing of the Constitution. Calder, 3 Dall., at 391 (opinion of Chase, J.); id., at 396 (opinion of Paterson, J.). Justice Chase’s now familiar opinion in Calder expounded those leg*42islative Acts which in his view implicated the core concern of the Ex Post Facto Clause:
“1st. Every law that makes an action done before the passing of the law, and which was innocent when done, criminal; and punishes such action. 2d. Every law that aggravates a crime, or makes it greater than it was, when committed. 3d. Every law that changes the punishment, and inflicts a greater punishment, than the law annexed to the crime, when committed. 4th. Every law that alters the legal rules of evidence, and receives less, or different, testimony, than the law required at the time of the commission of the offence, in order to convict the offender.” Id., at 390 (emphasis in original).
Early opinions of the Court portrayed this as an exclusive definition of ex post facto laws. Fletcher v. Peck, 6 Cranch 87, 138 (1810); Cummings v. Missouri, 4 Wall. 277, 325-326 (1867); id., at 391 (Miller, J., dissenting) (“This exposition of the nature of ex post facto laws has never been denied, nor has any court or any commentator on the Constitution added to the classes of laws here set forth, as coming within that clause”); Gut v. State, 9 Wall. 35, 38 (1870). So well accepted were these principles that the Court in Beazell v. Ohio, 269 U. S. 167 (1925), was able to confidently summarize the meaning of the Clause as follows:
“It is settled, by decisions of this Court so well known that their citation may be dispensed with, that any statute which punishes as a crime an act previously committed, which was innocent when done; which makes more burdensome the punishment for a crime, after its commission, or which deprives one charged with crime of any defense available according to law at the time when the act was committed, is prohibited as ex post facto. ” Id., at 169-170.
*43See also Dobbert v. Florida, 432 U. S. 282, 292 (1977).3
The Beazell formulation is faithful to our best knowledge of the original understanding of the Ex Post Facto Clause: Legislatures may not retroactively alter the definition of crimes or increase the punishment for criminal acts. Several early State Constitutions employed this definition of the term, and they appear to have been a basis for the Framers’ understanding of the provision. See The Federalist No. 44, p. 301 (J. Cooke ed. 1961) (J. Madison); 2 M. Farrand, Records of the Federal Convention of 1787, p. 376 (1911); Calder, 3 Dall., at 391-392 (opinion of Chase, J.); id., at 396-397 (opinion of Paterson, J.). The Constitutions of Maryland and North Carolina, for example, declared that “retrospective laws, punishing facts committed before the existence of such laws, and by them only declared criminal, are oppressive, unjust, and incompatible with liberty; wherefore no ex post facto law ought to be made.” See Constitution of Maryland, Declaration of Rights, Art. XV (1776); Constitution of North Carolina, Declaration of Rights, Art. XXIV (1776). Other State Constitutions, though not using the phrase “ex post facto,” included similar articles. See Declaration of Rights and Fundamental Rules of the Delaware State § 11 (1776); Constitution or Form of Government for the Commonwealth of Massachusetts, Declaration of Rights, Art. XXIV (1780).
*44Another historical reference, Blackstone’s Commentaries, which was discussed by the Framers during debates on the Ex Post Facto Clause, see 2 M. Farrand, Records of the Federal Convention of 1787, pp. 448-449 (1911), and deemed an authoritative source of the technical meaning of the term in Calder, see 3 Dall., at 391 (opinion of Chase, J.); id., at 396 (opinion of Paterson, J.), buttresses this understanding. According to Blackstone, a law is ex post facto “when after an action (indifferent in itself) is committed, the legislator then for the first time declares it to have been a crime, and inflicts a punishment upon the person who has committed it.” 1 W. Blackstone, Commentaries * 46. Although increased punishments are not mentioned explicitly in the historical sources, the Court has never questioned their prohibition, apparently on the theory that “[t]he enhancement of a crime, or penalty, seems to come within the same mischief as the creation of a crime or penalty.” Calder, supra, at 397 (opinion of Paterson, J.). The Beazell definition, then, is faithful to the use of the term “ex post facto law” at the time the Constitution was adopted.
Respondent concedes that Tex. Code Crim. Proc. Ann., Art. 37.10(b) (Vernon Supp. 1990), does not fall within any of the Beazell categories and, under that definition, would not constitute an ex post facto law as applied to him. The new statute is a procedural change that allows reformation of improper verdicts. It does not alter the definition of the crime of aggravated sexual abuse, of which Youngblood was convicted, nor does it increase the punishment for which he is eligible as a result of that conviction. Nevertheless, respondent maintains that this Court’s decisions have not limited the scope of the Ex Post Facto Clause to the finite Beazell categories, but have stated more broadly that retroactive legislation contravenes Art. I, § 10, if it deprives an accused of a “substantial protection” under law existing at the time of the crime. He argues that the new trial guaranteed him by former Texas law.is such a protection.
*45Several of our cases have described as “procedural” those changes which, even though they work to the disadvantage of the accused, do not violate the Ex Post Facto Clause. Dobbert v. Florida, supra, at 292-293, and n. 6; Beazell v. Ohio, 269 U. S., at 171; Mallett v. North Carolina, 181 U. S. 589, 597 (1901). While these cases do not explicitly define what they mean by the word “procedural,” it is logical to think that the term refers to changes in the procedures by which a criminal case is adjudicated, as opposed to changes in the substantive law of crimes. Respondent correctly notes, however, that we have said that a procedural change may constitute an ex post facto violation if it “affect[s] matters of substance,” Beazell, supra, at 171, by depriving a defendant of “substantial protections with which the existing law surrounds the person accused of crime,” Duncan v. Missouri, 152 U. S. 377, 382-383 (1894), or arbitrarily infringing upon “substantial personal rights.” Malloy v. South Carolina, 237 U. S. 180, 183 (1915); Beazell, supra, at 171.
We think this language from the cases cited has imported confusion into the interpretation of the Ex Post Facto Clause. The origin of the rather amorphous phrase, “substantial protections,” appears to lie in a 19th-century treatise on constitutional law by Professor Thomas Cooley. T. Cooley, Constitutional Limitations * 272. According to Cooley, who notably assumed the Calder construction of the Ex Post Facto Clause to be correct, Constitutional Limitations * 265, a legislature “may prescribe altogether different modes of procedure in its discretion, though it cannot lawfully, we think, in so doing, dispense with any of those substantial protections with which the existing law surrounds the person accused of crime.” Id., at *272.
This Court’s decision in Duncan v. Missouri, supra, subsequently adopted that phraseology:
“[A]n ex post facto law is one which imposes a punishment for an act which was not punishable at the time it was committed; or an additional punishment to that then *46prescribed; or changes the rules of evidence by which less or different testimony is sufficient to convict than was then required; or, in short, in relation to the offence or its consequences, alters the situation of a party to his disadvantage; but the prescribing of different modes or procedure and the abolition of courts and creation of new ones, leaving untouched all the substantial protections with which the existing law surrounds the person accused of crime, are not considered within the constitutional inhibition. Cooley Const. Lim. (5th ed.) 329.” Id., at 382-383 (other citations omitted) (emphasis added).
Later, in Malloy v. South Carolina, supra, we stated that even with regard to procedural changes, the Ex Post Facto Clause was “intended to secure substantial personal rights against arbitrary and oppressive legislative action.” Id., at 183. We repeated that recognition in Beazell itself, while also emphasizing that the provision was “not to limit the legislative control of remedies and modes of procedure which do not affect matters of substance.” Beazell, supra, at 171.
We think the best way to make sense out of this discussion in the cases is to say that by simply labeling a law “procedural,” a legislature does not thereby immunize it from scrutiny under the Ex Post Facto Clause. See Gibson v. Mississippi, 162 U. S. 565, 590 (1896). Subtle ex post facto violations are no more permissible than overt ones. In Beazell, supra, we said that the constitutional prohibition is addressed to laws, “whatever their form,” which make innocent acts criminal, alter the nature of the offense, or increase the punishment. Id., at 170. But the prohibition which may not be evaded is the one defined by the Calder categories. See Duncan, supra, at 382; Malloy, supra, at 183-184. The references in Duncan and Malloy to “substantial protections” and “personal rights” should not be read to adopt without explanation an undefined enlargement of the Ex Post Facto Clause.
*47Two decisions of this Court, relied upon by respondent, do not fit into this analytical framework. In Kring v. Missouri, 107 U. S. 221 (1883), the Court said “it is not to be supposed that the opinion in [Calder v. Bull] undertook to define, by way of exclusion, all the cases to which the constitutional provision would be applicable.” Id., at 228. It defined an ex post facto law, inter alia, as one which, “ ‘in relation to the offence or its consequences, alters the situation of a party to his disadvantage.”’ Id., at 228-229 (quoting United States v. Hall, 26 F. Cas. 84, 86 (No. 15,285) (D Pa. 1809)) (emphasis deleted). And in Thompson v. Utah, 170 U. S. 343 (1898), the Court held that a change in Utah law reducing the size of juries in criminal cases from 12 persons to 8 deprived Thompson of “a substantial right involved in his liberty” and violated the Ex Post Facto Clause. Id., at 352.
Neither of these decisions, in our view, is consistent with the understanding of the term “ex post facto law” at the time the Constitution was adopted. Nor has their reasoning been followed by this Court since Thompson was decided in 1898. These cases have caused confusion in state and lower federal courts about the scope of the Ex Post Facto Clause, as exemplified by the opinions of the District Court and Court of Appeals in this case. See also Murphy v. Kentucky, 465 U. S. 1072, 1073 (1984) (White, J., dissenting from denial of certio-rari) (noting “the evident confusion among lower courts concerning the application of the Ex Post Facto Clause to changes in rules of evidence and procedure”); United States v. Kowal, 596 F. Supp. 375, 377 (Conn. 1984) (Supreme Court jurisprudence applying ex post facto prohibition to retroactive procedural changes “is not all of one piece”); L. Tribe, American Constitutional Law 638 (2d ed. 1988) (procedural changes upheld by the Court “can hardly be distinguished in any functional way from those invalidated”).
The earlier decision, Kring v. Missouri, was a capital case with a lengthy procedural history. Kring was charged with first-degree murder, but pursuant to a plea agreement, he *48pleaded guilty to second-degree murder. The plea was accepted by the prosecutor and the trial court, and he was sentenced to 25 years in prison. He appealed the judgment, however, on the ground that his plea agreement provided for a sentence of no more than 10 years. The State Supreme Court reversed the judgment and remanded for further proceedings. In the trial court, Kring refused to withdraw his guilty plea to second-degree murder and refused to renew his plea of not guilty to first-degree murder, insisting instead that the acceptance of his earlier plea constituted an acquittal on the greater charge. The trial court, over Kring’s objection, directed a general plea of not guilty to be entered, and upon retrial, he was convicted of first-degree murder and sentenced to death.
At the time the crime was committed, Missouri law provided that a defendant’s plea of guilty to second-degree murder, if accepted by the prosecutor and the court, served as an acquittal of the charge of first-degree murder. After the crime, but before Kring made his plea, a new Missouri Constitution abrogated that rule. The State was thus free, as a matter of Missouri law, to retry Kring for first-degree murder after his conviction and the 25-year sentence for second-degree murder were vacated. The Supreme Court of Missouri held that the new law did not violate the Ex Post Facto Clause, because it effected only a change in criminal procedure.
This Court reversed by a vote of 5 to 4. As support for the view that Calder did not define an exclusive list of legislative Acts falling within the constitutional prohibition, Justice Miller’s opinion for the Court quoted a jury charge given by Justice Washington sitting in the District Court: “‘[A]n ex post facto law is one which, in its operation, makes that criminal which was not so at the time the action was performed; or which increases the punishment, or, in short, which, in relation to the offence or its consequences, alters the situation of a party to his disadvantage.’ ” Kring, supra, at 228-229 *49(quoting United States v. Hall, supra, at 86) (emphasis in original). Applying that test, the Court concluded that because the new Missouri Constitution denied Kring the benefit of an implied acquittal which the previous law provided, it “altered the situation to his disadvantage,” and his conviction for first-degree murder was void. Kring, supra, at 235-236.
The Court’s departure from Calder’s explanation of the original understanding of the Ex Post Facto Clause was, we think, unjustified. The language in the Hall case, heavily relied upon in Kring and repeated in other decisions thereafter, does not support a more expansive definition of ex post facto laws.
In Hall, a vessel owner was sued by the United States for forfeiture of an embargo bond obliging him to deliver certain cargo to Portland, Me. As a legal excuse, the defendant argued that a severe storm had disabled his vessel and forced him to land in Puerto Rico, where he was forced by the Puerto Rican government to sell the cargo. In dicta, Justice Washington hypothesized that, according to the law in effect at the time Hall forfeited the cargo, an “unavoidable accident” was an affirmative defense to a charge of failing to deliver cargo. His jury instruction then explained that a subsequent law imposing an additional requirement for the affirmative defense— that the vessel or cargo actually be lost at sea as a result of the unavoidable accident — would deprive Hall of a defense of his actions available at the time he sold the cargo and thus be an invalid ex post facto law.
This analysis is consistent with the Beazell framework. A law that abolishes an affirmative defense of justification or excuse contravenes Art. I, § 10, because it expands the scope of a criminal prohibition after the act is done. It appears, therefore, that Justice Washington’s reference to laws “relating] to the offence or its consequences,” was simply shorthand for legal changes altering the definition of an offense or increasing a punishment. His jury charge should not be read to mean that the Constitution prohibits retrospective *50laws, other than those encompassed by the Calder categories, which “alte[r] the situation of a party to his disadvantage.” Nothing in the Hall case supports the broad construction of the ex post facto provision given by the Court in Kring.
It is possible to reconcile Kring with the numerous cases which have held that “procedural” changes do not result in ex post facto violations by saying that the change in Missouri law did take away a “defense” available to the defendant under the old procedure. But this use of the word “defense” carries a meaning quite different from that which appears in the quoted language from Beazell, where the term was linked to the prohibition on alterations in “the legal definition of the offense” or “the nature or amount of the punishment imposed for its commission.” Beazell, 269 U. S., at 169-170. The “defense” available to Kring under earlier Missouri law was not one related to the definition of the crime, but was based on the law regulating the effect of guilty pleas. Missouri had not changed any of the elements of the crime of murder, or the matters which might be pleaded as an excuse or justification for the conduct underlying such a charge; it had changed its law respecting the effect of a guilty plea to a lesser included offense. The holding in Kring can only be justified if the Ex Post Facto Clause is thought to include not merely the Calder categories, but any change which “alters the situation of a party to his disadvantage.” We think such a reading of the Clause departs from the meaning of the Clause as it was understood at the time of the adoption of the Constitution, and is not supported by later cases. We accordingly overrule Kring.
The second case, Thompson v. Utah, must be viewed in historical context. Thompson was initially charged with his crime — grand larceny committed by stealing a calf — in 1895, when Utah was a Territory. He was tried by a jury of 12 persons and convicted. A new trial was subsequently granted, however, and in the meantime Utah was admitted *51into the Union as a State. The Constitution of the State of Utah provided that juries in noncapital cases would consist of 8 persons, not 12, and Thompson was retried and convicted by a panel of 8.
This Court reversed the conviction. It reasoned first that while Utah was a Territory, the Sixth Amendment applied to actions of the territorial government and guaranteed Thompson a right to a 12-person jury. 170 U. S., at 349-350. The Court then held that “the State did not acquire upon its admission into the Union the power to provide, in respect of felonies committed within its limits while it was a Territory, that they should be tried otherwise than by a jury such as is provided by the Constitution of the United States.” Id., at 350-351. Because the State Constitution “deprive[d] him of a substantial right involved in his liberty” and “materially altered] the situation to his disadvantage,” the Court concluded that Thompson’s conviction was prohibited by the Ex Post Facto Clause. Id., at 352-353.
The result in Thompson v. Utah foreshadowed our decision in Duncan v. Louisiana, 391 U. S. 145 (1968), which held that the Sixth Amendment right to trial by jury — then believed to mean a jury of 12, see, e. g., Patton v. United States, 281 U. S. 276, 288-289 (1930) — was incorporated and made applicable by the Fourteenth Amendment against the States. The Court held that since Utah was a Territory when Thompson’s crime was committed, and therefore obligated to provide a 12-person jury by the Sixth Amendment, the Ex Post Facto Clause prevented the State from taking away that substantial right from him when it became a State and was no longer bound by the Sixth Amendment as then interpreted. The right to jury trial provided by the Sixth Amendment is obviously a “substantial” one, but it is not a right that has anything to do with the definition of crimes, defenses, or punishments, which is the concern of the Ex Post Facto Clause. To the extent that Thompson v. Utah *52rested on the Ex Post Facto Clause and not the Sixth Amendment, we overrule it.4
The Texas statute allowing reformation of improper verdicts does not punish as a crime an act previously committed, which was innocent when done; nor make more burdensome the punishment for a crime, after its commission; nor deprive one charged with crime of any defense available according to law at the time when the act was committed. Its application to respondent therefore is not prohibited by the Ex Post Facto Clause of Art. I, § 10.
The judgment of the Court of Appeals is
Reversed.
In Bogany, the Texas Court of Criminal Appeals held that a jury verdict which included a punishment unauthorized by law was void at its inception and had to be set aside. It concluded that Texas law at that time did not give appellate courts authority to reform such verdicts.
Although there has been some debate within the Court about the accuracy of the historical discussion in Calder v. Bull, see Satterlee v. Matthewson, 2 Pet. 380, 381 (1829) (note by Johnson, J.), the Court has consistently adhered to the view expressed by Justices Chase, Paterson, and Iredell in Calder that the Ex Post Facto Clause applies only to penal statutes.
The Beazell definition omits the reference by Justice Chase in Calder v. Bull, 3 Dall. 386, 390 (1798), to alterations in the “legal rules of evidence.” See also Hopt v. Utah, 110 U. S. 574, 590 (1884) (approving procedural changes “leaving untouched the nature of the crime and the amount or degree of proof essential to conviction”). As cases subsequent to Calder make clear, this language was not intended to prohibit the application of new evidentiary rules in trials for crimes committed before the changes. Thompson v. Missouri, 171 U. S. 380, 386-387 (1898) (rejecting e.r post facto challenge to retroactive application of statute making admissible handwritten documents as handwriting exemplars): Hopt, supra, at 588-590 (upholding retroactive application of statute making felons competent to testify).
The Court’s holding in Thompson v. Utah, 170 U. S. 343 (1898), that the Sixth Amendment requires a jury panel of 12 persons is also obsolete. Williams v. Florida, 399 U. S. 78 (1970).