delivered the opinion of the Court.
Prior to his trial for robbery in the State of Florida, petitioner filed a “Motion for a Protective Order,” seeking to be excused from the requirements of Rule 1.200 of the Florida Rules of Criminal Procedure. That rule requires a defendant, on written demand of the prosecuting attorney, to give notice in advance of trial if the defendant intends to claim an alibi, and to furnish the prosecuting attorney with information as to the place where he claims to have been and with the names and addresses of the alibi witnesses he intends to use.1 In his motion petitioner openly declared his intent to claim an alibi, but objected to the further disclosure requirements on the ground that the rule “compels the Defendant in a criminal case to be a witness against himself” in violation of his Fifth and Fourteenth Amendment rights.2 The motion was denied. Petitioner also filed a pretrial motion to impanel a 12-man jury instead of the six-*80man jury provided by Florida law in all but capital cases.3 That motion too was denied. Petitioner was convicted as charged and was sentenced to life imprisonment.4 The District Court of Appeal affirmed, rejecting petitioner’s claims that his Fifth and Sixth Amendment rights had been violated. We granted certiorari.5 396 U. S. 955 (1969).
I
Florida’s notice-of-alibi rule is in essence a requirement that a defendant submit to a limited form of pretrial discovery by the State whenever he intends to rely at trial on the defense of alibi. In exchange for the defendant’s disclosure of the witnesses he proposes to use to establish that defense, the State in turn is required to notify the defendant of any witnesses it proposes to offer in rebuttal to that defense. Both sides are under a continuing duty promptly to disclose the names and addresses of additional witnesses bearing on the alibi as they become available. The threatened sanction for failure to comply is the exclusion at trial of the defendant’s alibi evidence — except for his own testimony — or, in the case of the State, the exclusion of the State’s evidence offered in rebuttal of the alibi.6
In this case, following the denial of his Motion for a Protective Order, petitioner complied with the alibi *81rule and gave the State the name and address of one Mary Scotty. Mrs. Scotty was summoned to the office of the State Attorney on the morning of the trial, where she gave pretrial testimony. At the trial itself, Mrs. Scotty, petitioner, and petitioner’s wife all testified that the three of them had been in Mrs. Scotty’s apartment during the time of the robbery. On two occasions during cross-examination of Mrs. Scotty, the prosecuting attorney confronted her with her earlier deposition in which she had given dates and times that in some respects did not correspond with the dates and times given at trial. Mrs. Scotty adhered to her trial story, insisting that she had been mistaken in her earlier testimony.7 The State also offered in rebuttal the testimony of one of the officers investigating the robbery who claimed that Mrs. Scotty had asked him for directions on the afternoon in question during the time when she claimed to have been in her apartment with petitioner and his wife.8
We need not linger over the suggestion that the discovery permitted the State against petitioner in this case deprived him of “due process” or a “fair trial.” Florida law provides for liberal discovery by the defendant against the State,9 and the notice-of-alibi rule is itself carefully hedged with reciprocal duties requiring state disclosure to the defendant. Given the ease with which an alibi can be fabricated, the State’s interest in protecting itself against an eleventh-hour defense is both obvious and legitimate. Reflecting this interest, notice-of-alibi provisions, dating at least from 1927,10 *82are now in existence in a substantial number of States.11 The adversary system of trial is hardly an end in itself; it is not yet a poker game in which players enjoy an absolute right always to conceal their cards until played.12 We find ample room in that system, at least as far as “due process” is concerned, for the instant Florida rule, which is designed to enhance the search for truth in the criminal trial by insuring both the defendant and the State ample opportunity to investigate certain facts crucial to the determination of guilt or innocence.
Petitioner’s major contention is that he was “compelled ... to be a witness against himself” contrary to the commands of the Fifth and Fourteenth Amendments because the notice-of-alibi rule required him to give the State the name and address of Mrs. Scotty in advance of trial and thus to furnish the State with information useful in convicting him. No pretrial statement of petitioner was introduced at trial; but armed with Mrs. Scotty’s name and address and the knowledge *83that she was to be petitioner’s alibi witness, the State was able to take her deposition in advance of trial and to find rebuttal testimony. Also, requiring him to reveal the elements of his defense is claimed to have interfered with his right to wait until after the State had presented its case to decide how to defend against it. We conclude, however, as has apparently every other court that has considered the issue,13 that the privilege against self-incrimination is not violated by a requirement that the defendant give notice of an alibi defense and disclose his alibi witnesses.14
■ The defendant in a criminal trial is frequently forced to testify himself and to call other witnesses in an effort to reduce the risk of conviction. When he presents his witnesses, he must reveal their identity and submit them to cross-examination which in itself may prove incriminating or which may furnish the State with leads to *84incriminating rebuttal evidence. That the defendant faces such a dilemma demanding a choice between complete silence and presenting a defense has never been thought an invasion of the privilege against compelled self-incrimination. The pressures generated by the State's evidence may be severe but they do not vitiate the defendant’s choice to present an alibi defense and witnesses to prove it, even though the attempted defense ends in catastrophe for the defendant. However “testimonial” or “incriminating” the alibi defense proves to be, it cannot be considered “compelled” within the meaning of the Fifth and Fourteenth Amendments.
Very similar constraints operate on the defendant when the State requires pretrial notice of alibi and the naming of alibi witnesses. Nothing in such a rule requires the defendant to rely on an alibi or prevents him from abandoning the defense; these matters are left to his unfettered choice.15 That choice must *85be made, but the pressures that bear on his pretrial decision are of the same nature as those that would induce him to call alibi witnesses at the trial: the force of historical fact beyond both his and the State’s control and the strength of the State’s case built on these facts. Response to that kind of pressure by offering evidence or testimony is not compelled self-incrimination transgressing the Fifth and Fourteenth Amendments..
In the case before us, the notice-of-alibi rule by itself in no way affected petitioner’s crucial decision to call alibi witnesses or added to the legitimate pressures leading to that course of action. At most, the rule only compelled petitioner to accelerate the timing of his disclosure, forcing him to divulge at an earlier date information that the petitioner from the beginning planned to divulge at trial. Nothing in the Fifth Amendment privilege entitles a defendant as a matter of constitutional right to await the end of the State’s case before announcing the nature of his defense, any more than it entitles him to await the jury’s verdict on the State’s case-in-chief before deciding whether or not to take the stand himself.
Petitioner concedes that absent the notice-of-alibi rule the Constitution would raise no bar to the court’s granting the State a continuance at trial on the ground of surprise as soon as the alibi witness is called.16 Nor *86would there be self-incrimination problems if, during that continuance, the State was permitted to do precisely what it did here prior to trial: take the deposition of the witness and find rebuttal evidence. But if so utilizing a continuance is permissible under the Fifth and Fourteenth Amendments, then surely the same result may be accomplished through pretrial discovery, as it was here, avoiding the necessity of a disrupted trial.17 We decline to hold that the privilege against compulsory self-incrimination guarantees the defendant the right to surprise the State with an alibi defense.
II
In Duncan v. Louisiana, 391 U. S. 145 (1968), we held that the Fourteenth Amendment guarantees a right to trial by jury in all criminal cases that — were they to be tried in a federal court — would come within the Sixth Amendment’s guarantee. Petitioner’s trial for robbery on July 3, 1968, clearly falls within the scope of that holding. See Baldwin v. New York, ante, p. 66; DeStefano v. Woods, 392 U. S. 631 (1968). The question in this case then is whether the constitutional guarantee of a trial by “jury” necessarily requires trial by exactly 12 persons, rather than some lesser number — in this case six. We hold that the 12-man panel is not a necessary ingredient of “trial by jury,” and that respondent’s refusal to impanel more than the six members provided for by Florida law did not violate petitioner’s Sixth Amendment rights as applied to the States through the Fourteenth.
We had occasion in Duncan v. Louisiana, supra, to review briefly the oft-told history of the development *87of trial by jury in criminal cases.18 That history revealed a long tradition attaching great importance to the concept of relying on a body of one’s peers to determine guilt or innocence as a safeguard against arbitrary law enforcement. That same history, however, affords little insight into the considerations that gradually led the size of that body to be generally fixed at 12.19 Some have suggested that the number 12 was fixed upon simply because that was the number of the presentment jury from the hundred, from which the petit jury developed.20 *88Other, less circular but more fanciful reasons for the number 12 have been given, “but they were all brought forward after the number was fixed,”21 and rest on little more than mystical or superstitious insights into the significance of “12.” Lord Coke’s explanation that the “number of twelve is much respected in holy writ, as 12 apostles, 12 stones, 12 tribes, etc.,”22 is typical.23 In *89short, while sometime in the 14th century the size of the jury at common law came to be fixed generally at 12,24 that particular feature of the jury system appears to have been a historical accident, unrelated to the great *90purposes which gave rise to the jury in the first place.26 The question before us is whether this accidental feature of the jury has been immutably codified into our Constitution.
This Court’s earlier decisions have assumed an affirmative answer to this question. The leading case so construing the Sixth Amendment is Thompson v. Utah, 170 U. S. 343 (1898). There the defendant had been tried and convicted by a 12-man jury for a crime committed in the Territory of Utah. A new trial was granted, but by that time Utah had been admitted as a State. The defendant’s new trial proceeded under Utah’s Constitution, providing for a jury of only eight members. This Court reversed the resulting conviction, holding that Utah’s constitutional provision was an ex post facto law as applied to the defendant. In reaching its conclusion, the Court announced that the Sixth Amendment was applicable to the defendant’s trial when Utah was a Territory, and that the jury referred to in the Amendment was a jury “constituted, as it was at common law, of twelve persons, neither more nor less.” 170 U. S., at 349. Arguably unnecessary for the result,26 *91this announcement was supported simply by referring to the Magna Carta,27 and by quoting passages from treatises which noted — what has already been seen— that at common law the jury did indeed consist of 12. Noticeably absent was any discussion of the essential step in the argument: namely, that every feature of the jury as it existed at common law — whether incidental or essential to that institution — was necessarily included in the Constitution wherever that document referred to a “jury.” 28 Subsequent decisions have reaffirmed the *92announcement in Thompson, often in dictum29 and usually by relying — where there was any discussion of the issue at all — solely on the fact that the common-law jury consisted of 12.30 See Patton v. United States, 281 U. S. 276, 288 (1930); 31 Rassmussen v. United States, 197 U. S. 516, 519 (1905); Maxwell v. Dow, 176 U. S. 581, 586 (1900).
While “the intent of the Framers” is often an elusive quarry, the relevant constitutional history casts considerable doubt on the easy assumption in our past decisions that if a given feature existed in a jury at common law in 1789, then it was necessarily preserved in the Con*93stitution. Provisions for jury trial were first placed in the Constitution in Article Ill’s provision that “[t]he Trial of all Crimes . . . shall be by Jury; and such Trial shall be held in the State where the said Crimes shall have been committed.” 32 The “very scanty history [of this provision] in the records of the Constitutional Convention” 33 sheds little light either way on the intended correlation between Article Ill’s “jury” and the features of the jury at common law.34 Indeed, pending and after the adoption of the Constitution, fears were expressed that Article Ill’s provision failed to preserve the common-law right to be tried by a “jury of the vicinage.” 35 That concern, as well as the concern *94to preserve the right to jury in civil as well as criminal cases, furnished part of the impetus for introducing amendments to the Constitution that ultimately resulted in the jury trial provisions of the Sixth and Seventh Amendments. As introduced by James Madison in the House, the Amendment relating to jury trial in criminal cases would have provided that:
“The trial of all crimes . . . shall be by an impartial jury of freeholders of the vicinage, with the requisite of unanimity for conviction, of the right of challenge, and other accustomed requisites . .. 36
The Amendment passed the House in substantially this form, but after more than a week of debate in the Senate it returned to the House considerably altered.37 While records of the actual debates that occurred in *95the Senate are not available,38 a letter from Madison to Edmund Pendleton on September 14, 1789, indicates that one of the Senate’s major objections was to the “vicinage” requirement in the House version.39 A conference committee was appointed. As reported in a second letter by Madison on September 23, 1789, the Senate remained opposed to the vicinage requirement, partly because in its view the then-pending judiciary bill — which was debated at the same time as the Amendments — adequately preserved the common-law vicinage feature, making it unnecessary to freeze that requirement into the Constitution. “The Senate,” wrote Madison:
“are . . . inflexible in opposing a definition of the locality of Juries. The vicinage they contend is either too vague or too strict a term; too vague if depending on limits to be fixed by the pleasure of the law, too strict if limited to the county. It was proposed to insert after the word Juries, 'with the accustomed requisites,’ leaving the definition to be construed according to the judgment of professional *96men. Even this could not be obtained. . . . The Senate suppose, also, that the provision for vicinage in the Judiciary bill will sufficiently quiet the fears which called for an amendment on this point.”40
The version that finally emerged from the Committee was the version that ultimately became the Sixth Amendment, ensuring an accused:
“the right to a speedy and public trial, by an impartial jury of the State and district wherein the crime shall have been committed, which district shall have been previously ascertained by law . . . .”
Gone were the provisions spelling out such common-law features of the jury as “unanimity,” or “the accustomed requisites.” And the “vicinage” requirement itself had been replaced by wording that reflected a compromise between broad and narrow definitions of that term, and that left Congress the power to determine the actual size of the “vicinage” by its creation of judicial districts.41
Three significant features may be observed in this sketch of the background of the Constitution’s jury trial provisions. First, even though the vicinage requirement was as much a feature of the common-law jury as was the 12-man requirement,42 the mere reference to “trial by jury” in Article III was not interpreted to include that feature. Indeed, as the subsequent debates over the Amendments indicate, disagreement arose over whether the feature should be included at all in its common-law sense, resulting in the compromise described above. Second, provisions that would have explicitly *97tied the “jury” concept to the “accustomed requisites” of the time were eliminated. Such action is concededly open to the explanation that the “accustomed requisites” were thought to be already included in the concept of a “jury.” But that explanation is no more plausible than the contrary one: that the deletion had some substantive effect. Indeed, given the clear expectation that a substantive change would be effected by the inclusion or deletion of an explicit “vicinage” requirement, the latter explanation is, if anything, the more plausible. Finally, contemporary legislative and constitutional provisions indicate that where Congress wanted to leave no doubt that it was incorporating existing common-law features of the jury system, it knew how to use express language to that effect. Thus, the Judiciary bill, signed by the President on the same day that the House and Senate finally agreed on the form of the Amendments to be submitted to the States, provided in certain cases for the narrower “vicinage” requirements that the House had wanted to include in the Amendments.43 And the Seventh Amendment, providing for jury trial in civil cases, explicitly added that “no fact tried by a jury, shall be otherwise re-examined in any Court of the United States, than according to the rules of the common law.” 44
*98We do not pretend to be able to divine precisely what the word “jury” imported to the Framers, the First Congress, or the States in 1789. It may well be that the usual expectation was that the jury would consist of 12,45 and that hence, the most likely con-*99elusion to be drawn is simply that little thought was actually given to the specific question we face today. But there is absolutely no indication in “the intent of the Framers” of an explicit decision to equate the constitutional and common-law characteristics of the jury. Nothing in this history suggests, then, that we do violence to the letter of the Constitution by turning to other than purely historical considerations to determine which features of the jury system, as it existed at common law, were preserved in the Constitution. The relevant inquiry, as we see it, must be the function that the particular feature performs and its relation to the *100purposes of the jury trial. Measured by this standard, the 12-man requirement cannot be regarded as an indispensable component of the Sixth Amendment.
The purpose of the jury trial, as we noted in Duncan, is to prevent oppression by the Government. “Providing an accused with the right to be tried by a jury of his peers gave him an inestimable safeguard against the corrupt or overzealous prosecutor and against the compliant, biased, or eccentric judge.” Duncan v. Louisiana, supra, at 156. Given this purpose, the essential feature of a jury obviously lies in the interposition between the accused and his accuser of the commonsense judgment of a group of laymen, and in the community participation and shared responsibility that results from that group’s determination of guilt or innocence. The performance of this role is not a function of the particular number of the body that makes up the jury. To be sure, the number should probably be large enough to promote group deliberation, free from outside attempts at intimidation, and to provide a fair possibility for obtaining a representative cross-section of the community. But we find little reason to think that these goals are in any meaningful sense less likely to be achieved when the jury numbers six, than when it numbers 12 — particularly if the requirement of unanimity is retained.46 And, certainly the reliability of the jury *101as a factfinder hardly seems likely to be a function of its size.
It might be suggested that the 12-man jury gives a defendant a greater advantage since he has more “chances” of finding a juror who will insist on acquittal and thus prevent conviction. But the advantage might just as easily belong to the State, which also needs only one juror out of twelve insisting on guilt to prevent acquittal.47 What few experiments have occurred — usually in the civil area — indicate that there is no discernible difference between the results reached by the two different-sized juries.48 In short, neither currently available evidence nor theory49 suggests that the 12-man *102jury is necessarily more advantageous to the defendant than a jury composed of fewer members.
Similarly, while in theory the number of viewpoints represented on a randomly selected jury ought to increase as the size of the jury increases, in practice the difference between the 12-man and the six-man jury in terms of the cross-section of the community represented seems likely to be negligible. Even the 12-man jury cannot insure representation of every distinct voice in the community, particularly given the use of the peremptory challenge. As long as arbitrary exclusions of a particular class from the jury rolls are forbidden, see, e. g., Carter v. Jury Commission, 396 U. S. 320, 329-330 (1970), the concern that the cross-section will be significantly diminished if the jury is decreased in size from 12 to six seems an unrealistic one.
We conclude, in short, as we began: the fact that the jury at common law was composed of precisely 12 is a historical accident, unnecessary to effect the purposes of the jury system and wholly without significance “except to mystics.” Duncan v. Louisiana, supra, at 182 (Harlan, J., dissenting). To read the Sixth Amendment as *103forever codifying a feature so incidental to the real purpose of the Amendment is to ascribe a blind formalism to the Framers which would require considerably more evidence than we have been able to discover in the history and language of the Constitution or in the reasoning of our past decisions. We do not mean to intimate that legislatures can never have good reasons for concluding that the 12-man jury is preferable to the smaller jury, or that such conclusions — reflected in the provisions of most States and in our federal system50— are in any sense unwise. Legislatures may well have their own views about the relative value of the larger and smaller juries, and may conclude that, wholly apart from the jury’s primary function, it is desirable to spread the collective responsibility for the determination of guilt among the larger group. In capital cases, for example, it appears that no State provides for less than 12 jurors— a fact that suggests implicit recognition of the value of the larger body as a means of legitimating society’s decision to impose the death penalty. Our holding does no more than leave these considerations to Congress and the States, unrestrained by an interpretation of the Sixth Amendment that would forever dictate the precise number that can constitute a jury. Consistent with this holding, we conclude that petitioner’s Sixth Amendment rights, as applied to the States through the Fourteenth Amendment, were not violated by Florida’s decision to provide a six-man rather than a 12-man jury. The judgment of the Florida District Court of Appeal is
Affirmed.
Mr. Justice Blackmun took no part in the consideration or decision of this case.*104APPENDIX TO OPINION OF THE COURT
Fla. Rule Crina. Proc. 1.200:
“Upon the written demand of the prosecuting attorney, specifying as particularly as is known to such prosecuting attorney, the place, date and time of the commission of the crime charged, a defendant in a criminal case who intends to offer evidence of an alibi in his defense shall, not less than ten days before trial or such other time as the court may direct, file and serve upon such prosecuting attorney a notice in writing of his intention to claim such alibi, which notice shall contain specific information as to the place at which the defendant claims to have been at the time of the alleged offense and, as particularly as is known to defendant or his attorney, the names and addresses of the witnesses by whom he proposes to establish such alibi. Not less than five days after receipt of defendant's witness list, or such other times as the court may direct, the prosecuting attorney shall file and serve upon the defendant the names and addresses (as particularly as are known to the prosecuting attorney) of the witnesses the State proposes to offer in rebuttal to discredit the defendant’s alibi at the trial of the cause. Both the defendant and the prosecuting attorney shall be under a continuing duty to promptly disclose the names and addresses of additional witnesses which come to the attention of either party subsequent to filing their respective witness lists as provided in this rule. If a defendant fails to file and serve a copy of such notice as herein required, the court may exclude evidence offered by such defendant for the purpose of proving an alibi, except the testimony of the defendant himself. If such notice is given by a *105defendant, the court may exclude the testimony of any witness offered by the defendant for the purpose of proving an alibi if the name and address of such witness as particularly as is known to defendant or his attorney is not stated in such notice. If the prosecuting attorney fails to file and serve a copy on the defendant of a list of witnesses as herein provided, the court may exclude evidence offered by the state in rebuttal to the defendant’s alibi evidence. If such notice is given by the prosecuting attorney, the court may exclude the testimony of any witness offered by the prosecuting attorney for the purpose of rebutting the defense of alibi if the name and address of such witness as particularly as is known to the prosecuting attorney is not stated in such notice. For good cause shown the court may waive the requirements of this rule.”
The full text of the -rule is set out in the appendix to this opinion, infra, at 104. Subsequent references to an appendix are to the separately bound appendix filed with the briefs in this case [hereinafter “App.”].
See App. 5.
Fla. Stat. §913.10 (1) (1967):
“Twelve men shall constitute a jury to try all capital cases, and six men shall constitute a jury to try all other criminal cases.”
See App. 82.
The Supreme Court of Florida had earlier held that it was without jurisdiction to entertain petitioner’s direct appeal from the trial court. See id., at 92. Under Florida law, the District Court of Appeal became the highest court from which a decision could be had. See Fla. Const., Art. V, § 4 (2); Fla. App. Rule 2.1a (5) (a); Ansin v. Thurston, 101 So. 2d 808, 810 (1958).
“For good cause shown” the court may waive the requirements of the rule. Fla. Rule Crim. Proc. 1.200.
See App. 58-60.
Id., at 65-66.
See Fla. Rule Crim. Proc. 1.220. These discovery provisions were invoked by petitioner in the instant case. See App. 3, 4, 8.
See Epstein, Advance Notice of Alibi, 55 J. Crim. L. C. & P. S. 29, 32 (1964).
In addition to Florida, at least 15 States appear to have alibi-notice requirements of one sort or another. See Ariz. Rule Crim. Proc. 192 B (1956); Ind. Ann. Stat. §§9-1631 to 9-1633 (1956); Iowa Code §777.18 (1966); Kan. Stat. Ann. §62-1341 (1964); Mich. Comp. Laws §§ 768.20, 768.21 (1948); Minn. Stat. § 630.14 (1967); N. J. Rule 3:5-9 (1958); N. Y. Code Crim. Proc. §295-1 (1958); Ohio Rev. Code Ann. § 2945.58 (1954); Okla. Stat., Tit. 22, § 585 (1969); Pa. Rule Crim. Proc. 312 (1970); S. D. Comp. Laws §§ 23-37-5, 23-37-6 (1967); Utah Code Ann. § 77-22-17 (1953); Vt. Stat. Ann., Tit. 13, §§ 6561, 6562 (1959); Wis. Stat. § 955.07 (1961). See generally 6 J. Wigmore, Evidence § 18556 (3d ed. 1940).
We do not, of course, decide that each of these alibi-notice provisions is necessarily valid in all respects; that conclusion must await a specific context and an inquiry, for example, into whether the defendant enjoys reciprocal discovery against the State.
See, e. g., Brennan,, The Criminal Prosecution: Sporting Event or Quest for Truth?, 1963 Wash. U. L. Q. 279, 292.
E. g., State v. Stump, 254 Iowa 1181, 119 N. W. 2d 210, cert. denied, 375 U. S. 853 (1963); State v. Baldwin, 47 N. J. 379, 221 A. 2d 199, cert. denied, 385 U. S. 980 (1966); People v. Rakiec, 260 App. Div. 452, 457-458, 23 N. Y. S. 2d 607, 612-613 (1940); Commonwealth v. Vecchiolli, 208 Pa. Super. 483, 224 A. 2d 96 (1966); see Jones v. Superior Court, 58 Cal. 2d 56, 372 P. 2d 919 (1962); Louisell, Criminal Discovery and Self-Incrimination: Roger Traynor Confronts the Dilemma, 53 Calif. L. Rev. 89 (1965); Traynor, Ground Lost and Found in Criminal Discovery, 39 N. Y. U. L. Rev. 228 (1964); Comment, The Self-Incrimination Privilege: Barrier to Criminal Discovery?, 51 Calif. L. Rev. 135 (1963); 76 Harv. L. Rev. 838 (1963).
We emphasize that this case does not involve the question of the validity of the threatened sanction, had petitioner chosen not to comply with the notice-of-alibi rule. Whether and to what extent a State can enforce discovery rules against a defendant who fails to comply, by excluding relevant, probative evidence is a question raising Sixth Amendment issues which we have no occasion to explore. Cf. Brief for Amicus Curiae 17-26. It is enough that no such penalty was exacted here.
Petitioner’s apparent suggestion to the contrary is simply not borne out by the facts of this case. The mere requirement that petitioner disclose in advance his intent to rely on an alibi in no way “fixed” his defense as of that point in time. The suggestion that the State, by referring to petitioner’s proposed alibi in opening or closing statements might have “compelled” him to follow through with the defense in order to avoid an unfavorable inference is a hypothetical totally without support in this record. The first reference to the alibi came from petitioner’s own attorney in his opening remarks; the State’s response did not come until after the defense had finished direct examination of Mrs. Scotty. Petitioner appears to raise this issue as a possible defect in alibi-notice requirements in general, without seriously suggesting that his choice of defense at trial in this case would have been different but for his prior compliance with the rule. Indeed, in his Motion for a Protective Order, petitioner freely disclosed his intent to rely on an alibi; his only objection was to the further requirement that he disclose the nature of the alibi and the name of the witness. On these facts, then, we simply are not confronted with the question *85of whether a defendant can be compelled in advance of trial to select a defense from which he can no longer deviate. We do not mean to suggest, though, that such a procedure must necessarily raise serious constitutional problems. See State ex rel. Simos v. Burke, 41 Wis. 2d 129, 137, 163 N. W. 2d 177, 181 (1968) (“[i]f we are discussing the right of a defendant to defer until the moment of his testifying the election between alternative and inconsistent alibis, we have left the concept of the trial as a search for truth far behind”).
See Reply Brief for Petitioner 2 and n. 1.
It might also be argued that the “testimonial” disclosures protected by the Fifth Amendment include only statements relating to the historical facts of the crime, not statements relating solely to what a defendant proposes to do at trial.
See Duncan v. Louisiana, 391 U. S. 145, 151-154 (1968).
In tracing the development of the jury from the time when the jury performed a different, “inquisitory” function, James R. Thayer notes the following:
“In early times the inquisition had no fixed number. In the Frankish empire we are told of 66, 41, 20, 17, 13, 11, 8, 7, 53, 15, and a great variety of other numbers. So also among the Normans it varied much, and ‘twelve has not even the place of the prevailing grundzahl;’ the documents show all sorts of numbers — 4, 5„ 6, 12, 13-18, 21, 27, 30, and so on. It seems to have been the recognitions under Henry II. that established twelve as the usual number; even then the number was not uniform.” The Jury and Its Development, 5 Harv. L. Rev. 295 (1892) (citations omitted).
See J. Thayer, A Preliminary Treatise on Evidence at the Common Law 85 (1898).
Similarly, Professor Scott writes:
“At the beginning of the thirteenth century twelve was indeed the usual but not the invariable number. But by the middle of the fourteenth century the requirement of twelve had probably become definitely fixed. Indeed this number finally came to be regarded with something like superstitious reverence.” A. Scott, Fundamentals of Procedure in Actions at Law 75-76 (1922) (footnotes omitted).
W. Holdsworth, A History of English Law 325 (1927); Wells, The Origin of the Petty Jury, 27 L. Q. Rev. 347, 357 (1911). The latter author traces the development of the 12-man petit jury through the following four stages. The first stage saw the development of the presentment jury, made up generally of 12 persons from the hundred, whose function was simply to charge the ac*88cused with a crime; the test of his guilt or innocence was by some other means, such as trial by ordeal, battle, or wager of law. In the second stage, the presentment jury began to be asked for its verdict on the guilt or innocence of the person it had accused, and hence began to function as both a petit and a grand jury. In the third stage, “combination juries” were formed to render the verdict in order to broaden the base of representation beyond the local hundred, or borough, to include the county. These juries were formed by adding one or more presentment juries from one or more hundreds, as well as certain officials such as coroners or knights. “These combination juries numbered from twenty-four to eighty-four jurors, and the number became embarrassingly large and unwieldy, and the sense of the personal responsibility of each juror was in danger of being lost.” Id., at 356. The obvious fourth step was the creation of a special jury “formed by selecting one or more jurors from each of several of the presentment juries of the hundreds, until the number twelve is reached . . . probably because that was the number of the presentment jury from the hundred. Therefore, just as the presentment jury represented the voice of the hundred in making the accusation, so the jury of ‘the country’, with the same number, represented the whole county in deciding whether the accused was guilty or not.” Id., at 357.
Neither of these authors hazards a guess as to why the presentment jury itself numbered 12.
Id., at 357.
1 E. Coke, Institutes of the Laws of England *155a (1st Amer. ed. 1812).
Thus John Proffatt in his treatise on jury trials notes that the reasons why the number of the petit jury is 12, are “quaintly given” in Duncombe’s Trials per Pais, as follows:
“[T]his number is no less esteemed by our own law than by holy writ. If the twelve apostles on their twelve thrones must *89try us in our eternal state, good reason hath the law to appoint the number twelve to try us in our temporal. The tribes of Israel were twelve, the patriarchs were twelve, and Solomon’s officers were twelve.” Trial by Jury 112 n. 4 (1877), quoting G. Duncombe, 1 Trials per Pais 92-93 (8th ed. 1766).
Attempts have also been made to trace the number 12 to early origins on the European Continent, particularly in Scandinavia. See F. Busch, 1 Law and Tactics in Jury Trials §24 (1959). See generally W. Forsyth, History of Trial by Jury 4 (1852); T. Repp, Trial by Jury (1832). But even as to the continental practice, no better reasons are discovered for the number 12. Thus Proffatt, in discussing the ancient Scandinavian tribunals, comments:
“Twelve was not only the common number throughout Europe, but was the favorite number in every branch of the polity and jurisprudence of the Gothic nations.
“The singular unanimity in the selection of the number twelve to compose certain judicial bodies, is a remarkable fact in the history of many nations. Many have sought to account for this general custom, and some have based it on religious grounds. One of the ancient kings of Wales, Morgan of Gla-Morgan, to whom is accredited the adoption of the trial by jury in A. D. 725, calls it the 'Apostolic Law.’ ‘For,’ said he, ‘as Christ and his twelve apostles were finally to judge the world, so human tribunals should be composed of the king and twelve wise men.’ ” Proffatt, Trial by Jury 11 n. 2 (1877) (citations omitted).
See also 1 L. Pike, A History of Crime in England 122 (1873).
In this connection it is interesting to note the following oath, required of the early 12-man jury:
“Hear this, ye Justices! that I will speak the truth of that which ye shall ask of me on the part of the king, and I will do faithfully to the best of my endeavour. So help me God, and these holy Apostles.” W. Forsyth, Trial by Jury 197 (1852).
See Proffatt, supra, at 42.
See supra, n. 19.
P. Devlin, Trial by Jury 8 (1956); F. Heller, The Sixth Amendment 64 (1951); W. Willoughby, Principles of Judicial Administration 503 (1929); Tamm, The Five-Man Civil Jury: A Proposed Constitutional Amendment, 51 Geo. L. J. 120, 128-130 (1962); Wiehl, The Six Man Jury, 4 Gonzaga L. Rev. 35, 38-39 (1968); see Thayer, supra, n. 19, at 89-90; White, Origin and Development of Trial by Jury, 29 Tenn. L. Rev. 8, 15-16, 17 (1959).
At the time of the crime and at the first trial the statutes of the Territory of Utah — wholly apart from the Sixth Amendment— ensured Thompson a 12-man jury. See 170 U. S., at 345. The Court found the ex post facto question easy to resolve, once it was assumed that Utah’s subsequent constitutional provision deprived Thompson of a right previously guaranteed him by the United States Constitution; the possibility that the same result might *91have been reached solely on the basis of the rights formerly accorded Thompson under the territorial statute was hinted at, but was not explicitly considered.
Whether or not the Magna Carta’s reference to a judgment by one's peers was a reference to a “jury” — a fact that historians now dispute, see, e. g., 1 F. Pollock & F. Maitland, The History of English Law Before the Time of Edward I, p. 173 n. 3 (2d ed. 1909); Frankfurter & Corcoran, Petty Federal Offenses and the Constitutional Guaranty of Trial by Jury, 39 Harv. L. Rev. 917, 922 n. 14 (1926) (criticizing Thompson v. Utah’s reliance on the document “long after scholars had exposed this ancient error”)— it seems clear that the Great Charter is not authority for fixing the number of the jury at 12. See W. McKechnie, Magna Carta 134-138, 375-382 (1958); Scott, Trial by Jury and the Reform of Civil Procedure, 31 Harv. L. Rev. 669, 672 (1918).
As the text indicates, the question is not whether the 12-man jury is traced to 1215 or to 1789, but whether that particular feature must be accepted as a sine qua non of the jury trial guaranteed by the Constitution. See Heller, supra, n. 25, at 64.
The Thompson opinion also reasoned that if a jury can be reduced from 12 to eight, then there was nothing to prevent its similarly being reduced to four or two or even zero, thus dispensing with the jury altogether. See 170 U. S., at 353. That bit of “logic,” resurrected today in Mr. Justice Harlan’s concurring opinion, post, at 126, suffers somewhat as soon as one recognizes that he can get off the “slippery slope” before he reaches the bottom. We have no occasion in this case to determine what minimum number can still constitute a “jury,” but we do not doubt that six is above that minimum.
A ruling that the Sixth Amendment refers to a common-law jury was essential to the holding in Rassmussen v. United States, 197 U. S. 516 (1905), where the Court held invalid a conviction by a six-man jury in Alaska. The ruling was accepted at the Government’s concession without discussion or citation; the major focus of the case was on the question whether the Sixth Amendment was applicable to the territory in question at all. See 197 U. S., at 519.
Similarly, cases interpreting the jury trial provisions of the Seventh Amendment generally leap from the fact that the jury possessed a certain feature at common law to the conclusion that that feature must have been preserved by the Amendment’s simple reference to trial by “jury.” E. g., Capital Traction Co. v. Hof, 174 U. S. 1, 13-14 (1899); American Publishing Co. v. Fisher, 166 U. S. 464, 468 (1897). While much of our discussion in this case may be thought to bear equally on the interpretation of the Seventh Amendment’s jury trial provisions, we emphasize that the question is not before us; we do not decide whether, for example, additional references to the “common law" that occur in the Seventh Amendment might support a different interpretation. See infra, at 97 and n. 44.
The Patton opinion furnishes an interesting illustration of the Court’s willingness to re-examine earlier assertions about the nature of “jury trial” in almost every respect except the 12-man-jury requirement. Patton reaffirmed the 12-man requirement with a simple citation to Thompson v. Utah, while at the same time discarding as “dictum” the equally dogmatic assertion in Thompson that the requirement could not be waived. See 281 U. S., at 293.
U. S. Const., Art. III, § 2, cl. 3.
Frankfurter & Corcoran, supra, n. 27, at 969.
The only attention given the jury trial provisions involved such questions as whether the right should also be extended to civil cases, see Henderson, The Background of the Seventh Amendment, 80 Harv. L. Rev. 289, 292-294 (1966), whether the wording should embrace the “trial of all crimes” or the “trial of all criminal offenses,” see Frankfurter & Corcoran, swpra, n. 27, at 969, and how to provide for the trial of crimes not committed in any State, id., at 969 n. 244. See 2 M. Farrand, Records of the Federal Convention 144, 173, 187, 433, 438, 676, 587-588, 601, 628 (1911). See also 4 id., at 121 (1937) (indexing all references to Art. Ill, §2, cl. 3 in Farrand’s records).
See Heller, supra, n. 25, at 31-33, 93; Warren, New Light on the History of the Federal Judiciary Act of 1789, 37 Harv. L. Rev. 49, 105 (1923). Technically, “vicinage” means neighborhood, and “vicin-age of the jury” meant jury of the neighborhood or, in medieval England, jury of the county. See 4 W. Blackstone, Commentaries *350-351. While Article III provided for venue, it did not impose the explicit juror-residence requirement associated with the concept of “vicinage.” See Maryland v. Brown, 295 F. Supp. 63, 80 (1969). In the Virginia Convention, Madison conceded that the omission was deliberate and defended it as follows:
“It was objected yesterday, that there was no provision for a jury from the vicinage. If it could have been done with safety, it would *94not have been opposed. It might so happen that a trial would be impracticable in the county. Suppose a rebellion in a whole district, would it not be impossible to get a jury? The trial by jury is held as sacred in England as in America. There are deviations of it in England: yet greater deviations have happened here since we established our independence, than have taken place there for a long time, though it be left to the legislative discretion. It is a misfortune in any case that this trial should be departed from, yet in some cases it is necessary. It must be therefore left to the discretion of the legislature to modify it according to circumstances. This is a complete and satisfactory answer.” 3 M. Far-rand, Records of the Federal Convention 332 (1911).
1 Annals of Cong. 435 (1789).
The Senate Journal indicates that every clause in the House version of the proposed Amendment was deleted except the clause relating to grand jury indictment. Senate Journal, Sept. 4, 1789, 1st Cong., 1st Sess., 71. A subsequent motion to restore the words providing for trial “by an impartial jury of the vicinage, with the requisite of unanimity for conviction, the right of challenge, and other accustomed requisites” failed of adoption. Senate Journal, Sept. 9, 1789, 1st Cong., 1st Sess., 77.
The principal source of information on the proceedings of the Senate in the First Congress is the Journal of Senator Maclay of Pennsylvania, who unfortunately was ill during the Senate debate on the amendments. See Journal of William Maclay 144-151 (1927); Heller, supra, n. 25, at 31-32.
Madison writes:
“The Senate have sent back the plan of amendments with some alterations, which strike, in my opinion, at the most salutary articles. In many of the States, juries, even in criminal cases, are taken from the State at large; in others, from districts of considerable extent; in very few from the County alone. Hence a dislike to the restraint with respect to vicinage, which has produced a negative on that clause. . . . Several others have had a similar fate.” Letter from James Madison to Edmund Pendleton, Sept. 14, 1789, in 1 Letters and Other Writings of James Madison 491 (1865).
Letter from James Madison to Edmund Pendleton, Sept. 23, 1789, in id., at 492-493. See generally Heller, supra, n. 25, at 28-34; Warren, supra, n. 35, at 118-132.
See Heller, supra, n. 25, at 93.
Proffatt, supra, n. 23, at 119; 1 G. Curtis, History of the Origin, Formation, and Adoption of the Constitution of the United States 23 (1863).
The Act provided in. § 29:
“That in cases punishable with death, the trial shall be had in the county where the offence was committed, or where that cannot be done without great inconvenience, twelve petit jurors at least shall be summoned from thence.” Act of Sept. 24, 1789, § 29, 1 Stat. 88.
Similarly, the First Continental Congress resolved in October 1774:
“That the respective colonies are entitled to the common law of England, and more especially to the great and inestimable privilege of being tried by their peers of the vicinage, according to the course of that law.” 1 Journals of the Continental Congress 69 (C. Ford ed. 1904) (emphasis added). And the Northwest Ordi-*98nanee of 1787 declared that the inhabitants of that Territory should ‘‘always be entitled to the benefits of the writs of habeas corpus, and of the trial by jury . . . and of judicial proceedings according to the course of the common law.” Ordinance of 1787, Art. II, 1 U. S. C. xxxviii (emphasis added). See Capital Traction Co. v. Hof, 174 U. S. 1, 5-8 (1899) (concluding from these sources that the explicit reference to the “common law” in the Seventh Amendment, referred to the rules of the common law of England, not the rules as modified by local or state practice).
One scholar, however, in investigating the reception of the English common law by the early American colonies, notes that the process:
“was not so simple as the legal theory would lead us to assume. While their general legal conceptions were conditioned by, and their terminology derived from, the common law, the early colonists were far from applying it as a technical system,, they often ignored it or denied its subsidiary force, and they consciously departed from many of its most essential principles.” Reinsch, The English Common Law in the Early American Colonies, in 1 Select Essays in Anglo-American Legal History 367, 415 (1907).
With respect to the jury trial in particular, while most of the colonies adopted the institution in its English form at an early date, more than one appears to have accepted the institution at various stages only with “various modifications.” See id., at 412. Thus Connecticut permitted majority decision in case of continued failure to agree, id., at 386, Virginia expressed regret at being unable to retain the “vicinage” requirement of the English jury, id., at 405, Pennsylvania permitted majority verdicts and employed juries of six or seven, id., at 398, and the Carolinas discontinued the unanimity requirement, 5 F. Thorpe, Federal and State Constitutions 2781 (1909) (Art. 69, “Fundamental Constitutions of Carolina”). See also Heller, supra, n. 25, at 13-21.
The States that had adopted Constitutions by the time of the Philadelphia Convention in 1787 appear for the most part to have either explicitly provided that the jury would consist of 12, see Va. Const, of 1776, § 8, in 7 F. Thorpe, Federal and State Constitutions *993813 (1909), or to have subsequently interpreted their jury trial provisions to include that requirement. In at least one instance involving conviction by eight jurors, a subsequent South Carolina decision interpreting the provision for trial by “jury,” refused to declare the 12-man requirement an essential feature of that institution, immune from change by the legislature. See State v. Starling, 15 Rich. 120, 134 (S. C. Ct. of Errors 1867). The conviction was affirmed without deciding the question, since the State had by that time adopted a Constitution specifically empowering the legislature to determine the number of jurors in certain inferior courts. South Carolina remains today one of apparently five States, including Florida, that provide for juries of less than 12 in felony eases where imprisonment for more than one year may be imposed. See La. Const., Art. 7, §41; La. Crim. Proc. Code Ann., Art. 779 (Supp. 1969); S. C. Const., Art. 1, §§ 18, 25; Art. 5, §22; S. C. Code Ann. §§ 15-618, 15-612 (1962); Tex. Const., Art. 1, §§10, 15; Art. 5, § 17; Tex. Code Crim. Proc., Arts. 4.07, 37.02 (1966); Tex. Pen. Code, Art. 1148 (1961); Utah Const., Art. 1, §§ 10, 12; Utah Code Ann. §78-46-5 (1953).
In addition, it appears that at least nine States presently provide for less than 12-man juries in trials of certain offenses carrying maximum penalties of one year’s imprisonment. See Brief for Appellee A13-A15, Baldwin v. New York, ante, p. 66 (collecting statutory provisions). See also 17 Mass. L. Q. No. 4, p. 12 (1932) (noting States that have interpreted the “right of trial by jury” to permit trial by less than 12 in certain cases). For a “poll of state practice,” see Mr. Justice Harlan’s concurring opinion, post, at 122, 136-137, and App.
intimate no view whether or not the requirement of unanimity is an indispensable element of the Sixth Amendment jury trial. While much of the above historical discussion applies as well to the unanimity as to the 12-man requirement, the former, unlike the latter, may well serve an important role in the jury function, for example, as a device for insuring that the Government bear the heavier burden of proof. See Hibdon v. United States, 204 F. 2d 834, 838 (C. A. 6th Cir. 1953); Tamm, supra, n. 25, at 139. But cf. Comment, Waiver of Jury Unanimity — Some Doubts About Reasonable Doubt, 21 U. Chi. L. Rev. 438, 441-443 *101(1954). See generally American Bar Association Project on Standards for Criminal Justice, Trial by Jury 42-45 (Approved Draft 1968).
It is true, of course, that the “hung jury” might be thought to result in a minimal advantage for the defendant, who remains uncon-victed and who enjoys the prospect that the prosecution will eventually be dropped if subsequent juries also “hang.” Thus a 100-man jury would undoubtedly be more favorable for defendants than a 12-man jury. But when the comparison is between 12 and six, the odds of continually “hanging” the jury seem slight, and the numerical difference in the number needed to convict seems unlikely to inure perceptibly to the advantage of either side.
See Wiehl, supra, n. 25, at 40-41; Tamm, supra, n. 25, at 134-136; Cronin, Six-Member Juries in District Courts, 2 Boston B. J. No. 4, p. 27 (1958); Six-Member Juries Tried in Massachusetts District Court, 42 J. Am. Jud. Soc. 136 (1958). See also New Jersey Experiments with Six-Man Jury, 9 Bull, of the Section of Jud. Admin, of the ABA (May 1966); Phillips, A Jury of Six in All Cases, 30 Conn. B. J. 354 (1956).
Studies of the operative factors contributing to small group deliberation and decisionmaking suggest that jurors in the minority on the first ballot are likely to be influenced by the proportional size of the majority aligned against them. See H. Kalven & H. Zeisel, The American Jury 462-463, 488-489 (1966); C. Hawkins, Interaction and Coalition Realignments in Consensus-Seeking Groups: A Study of Experimental Jury Deliberations 13, 146, 156, Aug. 17, *1021960 (unpublished thesis on file at Library of Congress); cf. Asch, Effects of Group Pressure Upon the Modification and Distortion of Judgments, in Readings in Social Psychology 2 (G. Swanson, T. Newcomb & E. Hartley et al., eds., 1952). See generally Note, On Instructing Deadlocked Juries, 78 Yale L. J. 100, 108 and n. 30 (and authorities cited), 110-111 (1968). Thus if a defendant needs initially to persuade four jurors that the State has not met its burden of proof in order to escape ultimate conviction by a 12-man jury, he arguably escapes by initially persuading half that number in a six-man jury; random reduction, within limits, of the absolute number of the jury would not affect the outcome. See also C. Joiner, Civil Justice and the Jury 31, 83 (1962) (concluding that the deliberative process should be the same in either the six- or 12-man jury).
See Fed. Rule Crim. Proc. 23 (b) (“[j]uries shall be of 12”).