delivered the opinion of the Court.
This case involves an aspect of the constitutional guarantee against being twice put in jeopardy. The precise issue is whether the federal rule governing the time when jeopardy attaches in a jury trial is binding on Montana through the Fourteenth Amendment. The federal rule is that jeopardy attaches when the jury is empaneled and sworn; a Montana statute provides that jeopardy does not attach until the first witness is sworn.1
I
The appellees, Merrel Cline2 and L. R. Bretz, were brought to trial in a Montana court on charges of grand larceny, obtaining money and property by false pretenses, and several counts of preparing or offering false evidence. A jury was empaneled and sworn following a three-day selection process. Before the first witness was sworn, however, the appellees filed a motion drawing attention to the allegation in the *30false-pretenses charge that the defendants’ illegal conduct began on January 13, 1974.3 Effective January 1, 1974, the particular statute relied on in that count of the information, Mont. Rev. Codes Ann. § 94-1805 (1947), had been repealed. The prosecutor moved to amend the information, claiming that “1974” was a typographical error, and that the date on which the defendants’ alleged violation of the statute had commenced was actually January 13, 1973, the same date alleged in the grand larceny count. The trial judge denied the prosecutor’s motion to amend the information and dismissed the false-pretenses count. The State promptly but unsuccessfully asked the Montana Supreme Court for a writ of supervisory control ordering the trial judge to allow the amendment.
Returning to the trial court, the prosecution then asked the trial judge to dismiss the entire information so that a new one could be filed. That motion was granted, and the jury was dismissed. A new information was then filed, charging the appellees with grand larceny and obtaining money and property by false pretenses. Both charges were based on conduct commencing January 13, 1973. Other than the change in dates, the new false-pretenses charge described essentially the same offense charged in the earlier defective count.
After a second jury had been selected and sworn, the ap-pellees moved to dismiss the new information, claiming that the Double Jeopardy Clauses of the United States and Montana Constitutions barred a second prosecution. The motion was denied, and the trial began. The appellees were found guilty on the false-pretenses count, and sentenced to terms of imprisonment. The Montana Supreme Court, which had previously denied appellees habeas corpus relief, State ex rel. Bretz v. Sheriff, 167 Mont. 363, 539 P. 2d 1191, affirmed the judgment as to Bretz on the ground that under state law *31jeopardy had not attached in the first trial. State v. Cline, 170 Mont. 520, 555 P. 2d 724.
In the meantime the appellees had brought a habeas corpus proceeding in a Federal District Court, again alleging that their convictions had been unconstitutionally obtained because the second trial violated the Fifth and Fourteenth Amendment guarantee against double jeopardy. The federal court denied the petition, holding that the Montana statute providing that jeopardy does not attach until the first witness is sworn does not violate the United States Constitution. The court held in the alternative that even if jeopardy had attached, a second prosecution was justified, as manifest necessity supported the first dismissal. Cunningham, v. District Court, 406 F. Supp. 430 (Mont.).4
The Court of Appeals for the Ninth Circuit reversed. 546 F. 2d 1336. It held that the federal rule governing the time when jeopardy attaches is an integral part of the constitutional guarantee, and thus is binding upon the States under the Fourteenth Amendment. The appellate court further held that there had been no manifest necessity for the Montana trial judge’s dismissal of the defective count, and, accordingly, that a second prosecution was not constitutionally permissible.5
Appellants appealed pursuant to 28 U. S. C. § 1254 (2), seeking review only of the holding of the Court of Appeals that Montana is constitutionally required to recognize that, for purposes of the constitutional guarantee against double jeopardy, jeopardy attaches in a criminal trial when the jury is empaneled and sworn. We postponed consideration of probable jurisdiction sub nom. Crist v. Cline, 430 U. S. 982, and the case was argued. Thereafter the case was set for *32reargument, 434 U. S. 980, and the parties were asked to address the following two questions:
“1. Is the rule heretofore applied in the federal courts— that jeopardy attaches in jury trials when the jury is sworn — constitutionally mandated?
“2. Should this Court hold that the Constitution does not require jeopardy to attach in any trial — state or federal, jury or nonjury- — -until the first witness is sworn?”
II
A
The unstated premise of the questions posed on reargument is that if the rule “that jeopardy attaches in jury trials when the jury is sworn” is “constitutionally mandated,” then that rule is binding on Montana, since “the double jeopardy prohibition of the Fifth Amendment . . . [applies] to the States through the Fourteenth Amendment,” and “the same constitutional standards” must apply equally in federal and state courts. Benton v. Maryland, 395 U. S. 784, 794—795. The single dispositive question, therefore, is whether the federal rule is an integral part of the constitutional guarantee.
The Double Jeopardy Clause of the Fifth Amendment is stated in brief compass: “[N]or shall any person be subject for the same offence to be twice put in jeopardy of life or limb.” But this deceptively plain language has given rise to problems both subtle and complex, problems illustrated by no less than eight cases argued here this very Term.6 This case, however, presents a single straightforward issue concerning the point during a jury trial when a defendant is deemed to have been put in jeopardy, for only if that point has once been *33reached does any subsequent prosecution of the defendant bring the guarantee against double jeopardy even potentially into play. Serfass v. United States, 420 U. S. 377, 388; Illinois v. Somerville, 410 U. S. 458, 467.
The Fifth Amendment guarantee against double jeopardy derived from English common law, which followed then, as it does now,7 the relatively simple rule that a defendant has been put in jeopardy only when there has been a conviction or an acquittal — after a complete trial.8 A primary purpose served by such a rule is akin to that served by the doctrines of res judicata and collateral estoppel — to preserve the finality of judgments.9 And it is clear that in the early years of our national history the constitutional guarantee against double jeopardy was considered to be equally limited in scope. As Mr. Justice Story explained:
“[The Double Jeopardy Clause] does not mean, that [a person] shall not be tried for the offence a second time, if the jury shall have been discharged without giving any verdict; . . . for, in such a case, his life or limb cannot judicially be said to have been put in jeopardy.” 3 J. Story, Commentaries on the Constitution § 1781, pp. 659-660 (1833).
But this constitutional understanding was not destined to endure. Beginning with this Court’s decision in United *34States v. Perez, 9 Wheat. 579, it became firmly established by the end of the 19th century that a defendant could be put in jeopardy even in a prosecution that did not culminate in a conviction or an acquittal, and this concept has been long established as an integral part of double jeopardy jurisprudence.10 Thus in Wade v. Hunter, 336 U. S. 684, 688, the Court was able accurately to say: “Past cases have decided that a defendant, put to trial before a jury, may be subjected to the kind of 'jeopardy’ that bars a second trial for the same *35offense even though his trial is discontinued without a verdict.” See also, e. g., Arizona v. Washington, 434 U. S. 497.
The basic reason for holding that a defendant is put in jeopardy even though the criminal proceeding against him terminates before verdict was perhaps best stated in Green v. United States, 355 U. S. 184, 187-188:
“The underlying idea, one that is deeply ingrained in at least the Anglo-American system of jurisprudence, is that the State with all its resources and power should not be allowed to make repeated attempts to convict an individual for an alleged offense, thereby subjecting him to embarrassment, expense and ordeal and compelling him to live in a continuing state of anxiety and insecurity, as well as enhancing the possibility that even though innocent he may be found guilty.”
Although it has thus long been established that jeopardy may attach in a criminal trial that ends inconclusively, the precise point at which jeopardy does attach in a jury trial might have been open to argument before this Court’s decision in Downum v. United States, 372 U. S. 734.11 There the Court held that the Double Jeopardy Clause prevented a second prosecution of a defendant whose first trial had ended just after the jury had been sworn and before any testimony had been taken. The Court thus necessarily pinpointed the stage in a jury trial when jeopardy attaches, and the Downum case has since been understood as explicit authority for the proposition that jeopardy attaches when the jury is empaneled and sworn. See United States v. Martin Linen Supply Co., 430 U. S. 564, 569; Serfass v. United States, 420 U. S., at 388.
The reason for holding that jeopardy attaches when the jury is empaneled and sworn lies in the need to protect the interest of an accused in retaining a chosen jury. That *36interest was described in Wade v. Hunter, supra, as a defendant’s “valued right to have his trial completed by a particular tribunal.” 336 U. S., at 689. It is an interest with roots deep in the historic development of trial by jury in the Anglo-American system of criminal justice.12 Throughout that history there ran a strong tradition that once banded together a jury should not be discharged until it had completed its solemn task of announcing a verdict.13
Regardless of its historic origin, however, the defendant’s “valued right to have his trial completed by a particular tribunal” is now within the protection of the constitutional guarantee against double jeopardy, since it is that “right” that lies at the foundation of the federal rule that jeopardy attaches when the jury is empaneled and sworn. United States v. Martin Linen Supply Co., supra; Serfass v. United States, supra, at 388; Illinois v. Somerville, 410 U. S., at 467; United States v. Jorn, 400 U. S. 470, 478-480, 484—485 (plurality opinion).
*37B
It follows that Montana’s view as to when jeopardy attaches is impermissible under the Fourteenth Amendment unless it can be said that the federal rule is not “at the core” of the Double Jeopardy Clause. See Pointer v. Texas, 380 U. S. 400, 406; Malloy v. Hogan, 378 U. S. 1, 11; Ker v. California, 374 U. S. 23, 33. In asking us to hold that it is not, appellants argue that the federal standard is no more than an arbitrarily chosen rule of convenience,14 similar in its lack of constitutional status to the federal requirement of a unanimous verdict by 12 jurors, which has been held not to bind the States. Apodaca v. Oregon, 406 U. S. 404; Williams v. Florida, 399 U. S. 78. But see Ballew v. Georgia, 435 U. S. 223.
If the rule that jeopardy attaches when the jury is sworn were simply an arbitrary exercise of linedrawing, this argument might well be persuasive, and it might reasonably be concluded that jeopardy does not constitutionally attach until the first witness is sworn, to provide consistency in jury and non jury trials.15 Indeed, it might then be concluded that the point of the attachment of jeopardy could be moved a few steps forward or backward without constitutional significance.16
But the federal rule as to when jeopardy attaches in a jury *38trial is not only a settled part of federal constitutional law. It is a rule that both reflects and protects the defendant’s interest in retaining a chosen jury. We cannot hold that this rule, so grounded, is only at the periphery of double jeopardy concerns. Those concerns — the finality of judgments, the minimization of harassing exposure to the harrowing experience of a criminal trial, and the valued right to continue with the chosen jury- — have combined to produce the federal law that in a jury trial jeopardy attaches when the jury is empaneled and sworn.
We agree with the Court of Appeals that the time when jeopardy attaches in a jury trial “serves as the lynchpin for all double jeopardy jurisprudence.” 546 F. 2d, at 1343. In Illinois v. Somerville, supra, at 467, a case involving the application of the Double Jeopardy Clause through the Fourteenth Amendment, the Court said that “jeopardy ‘attached’ when the first jury was selected and sworn.” Today we explicitly hold what Somerville assumed: The federal rule that jeopardy attaches when the jury is empaneled and sworn is an integral part of the constitutional guarantee against double jeopardy. The judgment is
Affirmed.
Montana Rev. Codes Ann. §95-1711 (3) (1947) provides in pertinent part:
“ [A] prosecution based upon the same transaction as a former prosecution is barred by such former prosecution under the following circumstances: ... (d) The former prosecution was improperly terminated. Except as provided in this subsection, there is an improper termination of a prosecution if the termination is for reasons not amounting to an acquittal, and it takes place after the first witness is sworn but before verdict. . . .”
See also State v. Cunningham, 166 Mont. 530, 535-536, 535 P. 2d 186, 189. In addition to Montana, Arizona also holds that jeopardy does not attach until “proceedings commence,” although this may be as early as the opening statement. Klinefelter v. Superior Court, 108 Ariz. 494, 495, 502 P. 2d 531, 532; State v. Mojarro Padilla, 107 Ariz. 134, 139-140, 483 P. 2d 549, 553. Until recently, New York had a similar rule. See Mizell v. Attorney General, 442 F. Supp. 868 (EDNY).
We were informed during argument that the conviction of Merrel Cline has been reversed, see State v. Cline, 170 Mont. 520, 555 P. 2d 724, and the charges against him dismissed. This appeal, therefore, has become moot as to him.
The motion, asked that the prosecution’s evidence be limited to the time period alleged in the information.
The Cunningham case, involving the same issue, was consolidated with the appellees’ ease.
In this Court the appellants specifically waived any challenge to the Court of Appeals’ ruling on manifest necessity, and we intimate no view as to its correctness.
In addition to the present case, see Arizona v. Washington, 434 U. S. 497; United States v. Wheeler, 435 U. S. 313; Burks v. United States, ante, p. 1; Greene v. Massey, ante, p. 19; Sanabria v. United States, post, p. 54; Swisher v. Brady, No. 77-653; United States v. Scott, post, p. 82.
11 Halsbury’s Laws of England ¶ 242 (4th ed. 1976).
Established at least by 1676, Turner’s Case, 89 Eng. Rep. 158, the rale was embodied in defensive pleas of former conviction or former acquittal. Although the pleas did not mention jeopardy, Blackstone commented that they were based on the “universal maxim . . . that no man is to be brought into jeopardy of his life, more than once, for the same offence.” 4 W. Blackstone, Commentaries *335. See generally J. Sigler, Double Jeopardy 1-37 (1969).
See Mayers & Yarbrough, Bis Vexari: New Trials and Successive Prosecutions, 74 Harv. L. Rev. 1 (1960). See also M. Friedland, Double Jeopardy 6 (1969); ALI, Administration of the Criminal Law: Double Jeopardy 7 (1935).
In perhaps the first expression of this concept, a state court in 1822 concluded that jeopardy may attach prior to a verdict, because “[tjhere is a wide different between a verdict given and the jeopardy of a verdict.” Commonwealth v. Cook, 6 Serg. & R. 577, 596 (Pa.).
In the Perez case, the trial judge had discharged a deadlocked jury, and the defendant argued in this Court that the discharge was a bar to a second trial. The case has long been understood as standing for the proposition that jeopardy attached during the first trial, but that despite the former jeopardy a second trial was not barred by the Double Jeopardy Clause because there was a “manifest necessity” for the discharge of the first jury. See, e. g., United States v. Tateo, 377 U. S. 463, 467; Wade v. Hunter, 336 U. S. 684, 689-690. In fact, a close reading of the short opinion in that case could support the view that the Court was not purporting to decide a constitutional question, but simply settling a problem arising in the administration of federal criminal justice. But to cast such a new light on Perez at this late date would be of academic interest only.
In two cases decided in the wake of Perez the Court simply followed its precedential authority: Simmons v. United States, 142 U. S. 148; Thompson v. United States, 155 U. S. 271. But it had become clear at least by the time of Kepner v. United States, 195 U. S. 100, decided in 1904, that jeopardy does attach even in a trial that does not culminate in a jury verdict: “[A] person has been in jeopardy when he is regularly charged with a crime before a tribunal properly organized and competent to try him .... Undoubtedly in those jurisdictions where a trial of one accused of crime can only be to a jury, and a verdict of acquittal or conviction must be by a jury, no legal jeopardy can attach until a jury has been called and charged with the deliverance of the accused.” Id., at 128. See also United States v. Dinitz, 424 U. S. 600; United States v. Wilson, 420 U. S. 332, 343-344; Gori v. United States, 367 U. S. 364.
But see Kepner v. United States, supra, at 128; n. 10, supra.
Trial juries were at first merely a substitute for other inscrutable methods of decisionmaking, such as trial by battle, compurgation, and ordeal. See 1 W. Holdsworth, A History of English Law 317 (7th ed. 1956). See also T. Plucknett, A Concise History of the Common Law 125 (5th ed. 1956). They soon evolved, however, into a more rational instrument of decisionmaking — serving as a representative group of peers to sit in judgment on a defendant’s guilt.
Illustrative of this tradition was the practice of keeping the jury together ynfed and without drink until it delivered its unanimous verdict. See Y. B. Trin. 14 Hen. VII, pi. 4. See Plucknett, supra, at 119. As Lord Coke put the matter: “A jury sworn and charged in case of life or member, cannot be discharged by the court or any other, but they ought to give a verdict.” 1 E. Coke, Institutes 227 (b) (6th ed. 1861). And an English court said as late as 1866: “[The rule] seems to command the confinement of the jury till death if they do not agree, and to avoid any such consequence an exception was introduced in practice which Blackstone has described by the words ‘except in case of evident necessity.’ ” Winsor v. The Queen, [1866] 1 .Q. B. 390, 394.
The United States as amicus curiae makes a similar argument.
In nonjury trials jeopardy does not attach until the first witness is sworn. Serfass v. United States, 420 U. S. 377, 388.
The United States alternatively proposes a due process sliding “interest balancing test” under which the further the trial has proceeded the more the justification required for a midtrial termination. Montana alternatively proposes that jeopardy should not be held to attach until a prima facie case has been made, on the premise that only then will a defendant truly be in jeopardy. The legal literature provides at least one other approach: jeopardy should attach “as soon as the process of selecting the jury begins.” See Schulhofer, Jeopardy and Mistrials, 125 U. Pa. L. Rev. 449, 512-514 (1977).