Justice THOMAS, dissenting.
The Court today holds that the Sixth Amendment requires the States to provide a criminal defendant the opportunity to impeach a jury's guilty verdict with juror testimony about a juror's alleged racial bias, notwithstanding a state procedural rule forbidding such testimony. I agree with Justice ALITO that the Court's decision is incompatible with the text of the Amendment it purports to interpret and with our precedents. I write separately to explain that the Court's holding also cannot be squared with the original understanding of the Sixth or Fourteenth Amendments.
I
The Sixth Amendment's protection of the right, "[i]n all criminal prosecutions,"
*872to a "trial, by an impartial jury," is limited to the protections that existed at common law when the Amendment was ratified. See, e.g., Apprendi v. New Jersey, 530 U.S. 466, 500, and n. 1, 120 S.Ct. 2348, 147 L.Ed.2d 435 (2000) (THOMAS, J., concurring); 3 J. Story, Commentaries on the Constitution of the United States § 1773, pp. 652-653 (1833) (Story) (explaining that "the trial by jury in criminal cases" protected by the Constitution is the same "great privilege" that was "a part of that admirable common law" of England); cf. 5 St. G. Tucker, Blackstone's Commentaries 349, n. 2 (1803). It is therefore "entirely proper to look to the common law" to ascertain whether the Sixth Amendment requires the result the Court today reaches. Apprendi, supra, at 500, n. 1, 120 S.Ct. 2348
The Sixth Amendment's specific guarantee of impartiality incorporates the common-law understanding of that term. See, e.g., 3 W. Blackstone, Commentaries on the Laws of England 365 (1769) (Blackstone) (describing English trials as "impartially just" because of their "caution against all partiality and bias" in the jury). The common law required a juror to have "freedome of mind" and to be "indifferent as hee stands unsworne." 1 E. Coke, First Part of the Institutes of the Laws of England § 234, p. 155a (16th ed. 1809); accord, 3 M. Bacon, A New Abridgment of the Law 258 (3d ed. 1768); cf. T. Cooley, A Treatise on the Constitutional Limitations Which Rest Upon the Legislative Power of the States of the American Union 319 (1868) ("The jury must be indifferent between the prisoner and the commonwealth"). Impartial jurors could "have no interest of their own affected, and no personal bias, or pre-possession, in favor [of] or against either party." Pettis v. Warren, 1 Kirby 426, 427 (Conn.Super.1788).
II
The common-law right to a jury trial did not, however, guarantee a defendant the right to impeach a jury verdict with juror testimony about juror misconduct, including "a principal species of [juror] misbehaviour"-"notorious partiality." 3 Blackstone 388. Although partiality was a ground for setting aside a jury verdict, ibid., the English common-law rule at the time the Sixth Amendment was ratified did not allow jurors to supply evidence of that misconduct. In 1770, Lord Mansfield refused to receive a juror's affidavit to impeach a verdict, declaring that such an affidavit "can't be read." Rex v. Almon, 5 Burr. 2687, 98 Eng. Rep. 411 (K.B.). And in 1785, Lord Mansfield solidified the doctrine, holding that "[t]he Court [could not] receive such an affidavit from any of the jurymen" to prove that the jury had cast lots to reach a verdict. Vaise v. Delaval, 1 T.R. 11, 99 Eng. Rep. 944 (K.B.).1
At the time of the founding, the States took mixed approaches to this issue. See Cluggage v. Swan, 4 Binn. 150, 156 (Pa.1811) (opinion of Yeates, J.) ("The opinions of American judges ... have greatly differed on the point in question"); Bishop v. Georgia, 9 Ga. 121, 126 (1850) (describing the common law in 1776 on this question as "in a transition state"). Many States followed *873Lord Mansfield's no-impeachment rule and refused to receive juror affidavits. See, e.g., Brewster v. Thompson, 1 N.J.L. 32 (1790) (per curiam ); Robbins v. Windover, 2 Tyl. 11, 14 (Vt.1802) ; Taylor v. Giger, 3 Ky. 586, 597-598 (1808) ; Price v. McIlvain, 2 Tread. 503, 504 (S.C. 1815) ; Tyler v. Stevens, 4 N.H. 116, 117 (1827) ; 1 Z. Swift, A Digest of the Laws of the State of Connecticut 775 (1822) ("In England, and in the courts of the United States, jurors are not permitted to be witnesses respecting the misconduct of the jury ... and this is, most unquestionably, the correct principle"). Some States, however, permitted juror affidavits about juror misconduct. See, e.g., Crawford v. State, 10 Tenn. 60, 68 (1821) ; Cochran v. Street, 1 Va. 79, 81 (1792). And others initially permitted such evidence but quickly reversed course. Compare, e.g., Smith v. Cheetham, 3 Cai. R. 57, 59-60 (N.Y.1805) (opinion of Livingston, J.) (permitting juror testimony), with Dana v. Tucker, 4 Johns. 487, 488-489 (N.Y.1809) (per curiam ) (overturning Cheetham ); compare also Bradley's Lessee v. Bradley, 4 Dall. 112, 1 L.Ed. 763 (1792) (permitting juror affidavits), with, e.g.,Cluggage, supra, at 156-158 (opinion of Yeates, J.) (explaining that Bradley was incorrectly reported and rejecting affidavits); compare also Talmadge v. Northrop, 1 Root 522 (Conn.1793) (admitting juror testimony), with State v. Freeman, 5 Conn. 348, 350-352 (1824) ("The opinion of almost the whole legal world is adverse to the reception of the testimony in question; and, in my opinion, on invincible foundations").
By the time the Fourteenth Amendment was ratified, Lord Mansfield's no-impeachment rule had become firmly entrenched in American law. See Lettow, New Trial for Verdict Against Law: Judge-Jury Relations in Early-Nineteenth Century America, 71 Notre Dame L. Rev. 505, 536 (1996) ("[O]pponents of juror affidavits had largely won out by the middle of the century"); 8 J. Wigmore, Evidence in Trials at Common Law § 2352, p. 697 (J. McNaughton rev. 1961) (Wigmore) (Lord Mansfield's rule "came to receive in the United States an adherence almost unquestioned"); J. Proffatt, A Treatise on Trial by Jury § 408, p. 467 (1877) ("It is a well established rule of law that no affidavit shall be received from a juror to impeach his verdict"). The vast majority of States adopted the no-impeachment rule as a matter of common law. See, e.g., Bull v. Commonwealth, 55 Va. 613, 627-628 (1857) ("[T]he practice appears to be now generally settled, to reject the testimony of jurors when offered to impeach their verdict. The cases on the subject are too numerous to be cited"); Tucker v. Town Council of South Kingstown, 5 R.I. 558, 560 (1859) (collecting cases); State v. Coupenhaver, 39 Mo. 430 (1867) ("The law is well settled that a traverse juror cannot be a witness to prove misbehavior in the jury in regard to their verdict"); Peck v. Brewer, 48 Ill. 54, 63 (1868) ("So far back as ... 1823, the doctrine was held that the affidavits of jurors cannot be heard to impeach their verdict"); Heffron v. Gallupe, 55 Me. 563, 566 (1868) (ruling inadmissible "depositions of ... jurors as to what transpired in the jury room"); Withers v. Fiscus, 40 Ind. 131, 131-132 (1872) ("In the United States it seems to be settled, notwithstanding a few adjudications to the contrary ..., that such affidavits cannot be received").2
*874The Court today acknowledges that the States "adopted the Mansfield rule as a matter of common law," ante, at 863, but ascribes no significance to that fact. I would hold that it is dispositive. Our common-law history does not establish that-in either 1791 (when the Sixth Amendment was ratified) or 1868 (when the Fourteenth Amendment was ratified)-a defendant had the right to impeach a verdict with juror testimony of juror misconduct. In fact, it strongly suggests that such evidence was prohibited. In the absence of a definitive common-law tradition permitting impeachment by juror testimony, we have no basis to invoke a constitutional provision that merely "follow[s] out the established course of the common law in all trials for crimes," 3 Story § 1785, at 662, to overturn Colorado's decision to preserve the no-impeachment rule, cf. Boumediene v. Bush, 553 U.S. 723, 832-833, 128 S.Ct. 2229, 171 L.Ed.2d 41 (2008) (Scalia, J., dissenting).
* * *
Perhaps good reasons exist to curtail or abandon the no-impeachment rule. Some States have done so, see Appendix to majority opinion, ante, and others have not. Ultimately, that question is not for us to decide. It should be left to the political process described by Justice ALITO. See post, at 876 - 878 (dissenting opinion). In its attempt to stimulate a "thoughtful, rational dialogue" on race relations, ante, at 871, the Court today ends the political process and imposes a uniform, national rule. The Constitution does not require such a rule. Neither should we.
I respectfully dissent.
Justice ALITO, with whom THE CHIEF JUSTICE and Justice THOMAS join, dissenting.
Our legal system has many rules that restrict the admission of evidence of statements made under circumstances in which confidentiality is thought to be essential. Statements made to an attorney in obtaining legal advice, statements to a treating physician, and statements made to a spouse or member of the clergy are familiar examples. See Trammel v . United States, 445 U.S. 40, 51, 100 S.Ct. 906, 63 L.Ed.2d 186 (1980). Even if a criminal defendant whose constitutional rights are at stake has a critical need to obtain and introduce evidence of such statements, long-established rules stand in the way. The goal of avoiding interference with confidential communications of great value has long been thought to justify the loss of important evidence and the effect on our justice system that this loss entails.
The present case concerns a rule like those just mentioned, namely, the age-old rule against attempting to overturn or "impeach" a jury's verdict by offering statements made by jurors during the course of deliberations. For centuries, it has been the judgment of experienced judges, trial attorneys, scholars, and lawmakers that allowing jurors to testify after a trial about what took place in the jury room would undermine the system of trial by jury that is integral to our legal system.
Juries occupy a unique place in our justice system. The other participants in a trial-the presiding judge, the attorneys, the witnesses-function in an arena governed by strict rules of law. Their every word is recorded and may be closely scrutinized for missteps.
When jurors retire to deliberate, however, they enter a space that is not regulated in the same way. Jurors are ordinary people. They are expected to speak, debate, argue, and make decisions the way ordinary people do in their daily lives. Our Constitution places great value on this way of thinking, speaking, and deciding. The jury trial right protects parties in *875court cases from being judged by a special class of trained professionals who do not speak the language of ordinary people and may not understand or appreciate the way ordinary people live their lives. To protect that right, the door to the jury room has been locked, and the confidentiality of jury deliberations has been closely guarded.
Today, with the admirable intention of providing justice for one criminal defendant, the Court not only pries open the door; it rules that respecting the privacy of the jury room, as our legal system has done for centuries, violates the Constitution. This is a startling development, and although the Court tries to limit the degree of intrusion, it is doubtful that there are principled grounds for preventing the expansion of today's holding.
The Court justifies its decision on the ground that the nature of the confidential communication at issue in this particular case-a clear expression of what the Court terms racial bias1 -is uniquely harmful to our criminal justice system. And the Court is surely correct that even a tincture of racial bias can inflict great damage on that system, which is dependent on the public's trust. But until today, the argument that the Court now finds convincing has not been thought to be sufficient to overcome confidentiality rules like the one at issue here.
Suppose that a prosecution witness gives devastating but false testimony against a defendant, and suppose that the witness's motivation is racial bias. Suppose that the witness admits this to his attorney, his spouse, and a member of the clergy. Suppose that the defendant, threatened with conviction for a serious crime and a lengthy term of imprisonment, seeks to compel the attorney, the spouse, or the member of the clergy to testify about the witness's admissions. Even though the constitutional rights of the defendant hang in the balance, the defendant's efforts to obtain the testimony would fail. The Court provides no good reason why the result in this case should not be the same.
I
Rules barring the admission of juror testimony to impeach a verdict (so-called "no-impeachment rules") have a long history. Indeed, they pre-date the ratification of the Constitution. They are typically traced back to Vaise v. Delaval, 1 T.R. 11, 99 Eng. Rep. 944 (K.B. 1785), in which Lord Mansfield declined to consider an affidavit from two jurors who claimed that the jury had reached its verdict by lot. See Warger v. Shauers, 574 U.S. ----, ----, 135 S.Ct. 521, 525-526, 190 L.Ed.2d 422 (2014). Lord Mansfield's approach "soon took root in the United States," ibid. , and "[b]y the beginning of [the 20th] century, if not earlier, the near-universal and firmly established common-law rule in the United States flatly prohibited the admission of juror testimony to impeach a jury verdict," Tanner v. United States, 483 U.S. 107, 117, 107 S.Ct. 2739, 97 L.Ed.2d 90 (1987) ; see 27 C. Wright & V. Gold, Federal Practice and Procedure: Evidence § 6071, p. 431 (2d ed. 2007) (Wright & Gold) (noting that the Mansfield approach "came to be accepted in almost all states").
In McDonald v. Pless, 238 U.S. 264, 35 S.Ct. 783, 59 L.Ed. 1300 (1915), this Court adopted a strict no-impeachment rule for *876cases in federal court. McDonald involved allegations that the jury had entered a quotient verdict-that is, that it had calculated a damages award by taking the average of the jurors' suggestions. Id., at 265-266, 35 S.Ct. 783. The Court held that evidence of this misconduct could not be used. Id., at 269, 35 S.Ct. 783. It applied what it said was "unquestionably the general rule, that the losing party cannot, in order to secure a new trial, use the testimony of jurors to impeach their verdict." Ibid . The Court recognized that the defendant had a powerful interest in demonstrating that the jury had "adopted an arbitrary and unjust method in arriving at their verdict." Id ., at 267, 35 S.Ct. 783. "But," the Court warned, "let it once be established that verdicts ... can be attacked and set aside on the testimony of those who took part in their publication and all verdicts could be, and many would be, followed by an inquiry in the hope of discovering something which might invalidate the finding." Ibid . This would lead to "harass[ment]" of jurors and "the destruction of all frankness and freedom of discussion and conference." Id ., at 267-268, 35 S.Ct. 783. Ultimately, even though the no-impeachment rule "may often exclude the only possible evidence of misconduct," relaxing the rule "would open the door to the most pernicious arts and tampering with jurors." Id ., at 268, 35 S.Ct. 783 (internal quotation marks omitted).
The firm no-impeachment approach taken in McDonald came to be known as "the federal rule." This approach categorically bars testimony about jury deliberations, except where it is offered to demonstrate that the jury was subjected to an extraneous influence (for example, an attempt to bribe a juror). Warger, supra, at 876, 135 S.Ct., at 526 ; Tanner, supra, at 117, 107 S.Ct. 2739 ;2 see 27 Wright & Gold § 6071, at 432-433.
Some jurisdictions, notably Iowa, adopted a more permissive rule. Under the Iowa rule, jurors were generally permitted to testify about any subject except their "subjective intentions and thought processes in reaching a verdict." Warger, supra, at 864, 135 S.Ct., at 526. Accordingly, the Iowa rule allowed jurors to "testify as to events or conditions which might have improperly influenced the verdict, even if these took place during deliberations within the jury room." 27 Wright & Gold § 6071, at 432.
Debate between proponents of the federal rule and the Iowa rule emerged during the framing and adoption of Federal Rule of Evidence 606(b). Both sides had their supporters. The contending arguments were heard and considered, and in the end the strict federal approach was retained.
An early draft of the Advisory Committee on the Federal Rules of Evidence included a version of the Iowa rule, 51 F.R.D. 315, 387-388 (1971). That draft was forcefully criticized, however,3 and the *877Committee ultimately produced a revised draft that retained the well-established federal approach. Tanner, supra, at 122, 107 S.Ct. 2739 ; see Committee on Rules of Practice and Procedure of the Judicial Conference of the United States, Revised Draft of Proposed Rules of Evidence for the United States Courts and Magistrates 73 (Oct. 1971). Expressly repudiating the Iowa rule, the new draft provided that jurors generally could not testify "as to any matter or statement occurring during the course of the jury's deliberations." Ibid. This new version was approved by the Judicial Conference and sent to this Court, which adopted the rule and referred it to Congress. 56 F.R.D. 183, 265-266 (1972).
Initially, the House rejected this Court's version of Rule 606(b) and instead reverted to the earlier (and narrower) Advisory Committee draft. Tanner, supra, at 123, 107 S.Ct. 2739 ; see H.R.Rep. No. 93-650, pp. 9-10 (1973) (criticizing the Supreme Court draft for preventing jurors from testifying about "quotient verdict[s]" and other "irregularities which occurred in the jury room"). In the Senate, however, the Judiciary Committee favored this Court's rule. The Committee Report observed that the House draft broke with "long-accepted Federal law" by allowing verdicts to be "challenge[d] on the basis of what happened during the jury's internal deliberations." S.Rep. No. 93-1277, p. 13 (1974) (S. Rep.). In the view of the Senate Committee, the House rule would have "permit[ted] the harassment of former jurors" as well as "the possible exploitation of disgruntled or otherwise badly-motivated ex-jurors." Id., at 14. This result would have undermined the finality of verdicts, violated "common fairness," and prevented jurors from "function[ing] effectively." Ibid. The Senate rejected the House version of the rule and returned to the Court's rule. A Conference Committee adopted the Senate version, see H.R. Conf. Rep. No. 93-1597, p. 8 (1974), and this version was passed by both Houses and was signed into law by the President.
As this summary shows, the process that culminated in the adoption of Federal Rule of Evidence 606(b) was the epitome of reasoned democratic rulemaking. The "distinguished, Supreme Court-appointed" members of the Advisory Committee went through a 7-year drafting process, "produced two well-circulated drafts," and "considered numerous comments from persons involved in nearly every area of court-related law." Rothstein, The Proposed Amendments to the Federal Rules of Evidence, 62 Geo. L.J. 125 (1973). The work of the Committee was considered and approved by the experienced appellate and trial judges serving on the Judicial Conference and by our predecessors on this Court. After that, the matter went to Congress, which "specifically understood, considered, and rejected a version of [the rule] that would have allowed jurors to testify on juror conduct during deliberations." Tanner, 483 U.S., at 125, 107 S.Ct. 2739. The judgment of all these participants in the process, which was informed by their assessment of an empirical issue, i.e., the effect that the competing Iowa rule would have had on the jury system, is entitled to great respect.
Colorado considered this same question, made the same judgment as the participants in the federal process, and adopted a very similar rule. In doing so, it joined *878the overwhelming majority of States. Ante, at 864 - 865. In the great majority of jurisdictions, strong no-impeachment rules continue to be "viewed as both promoting the finality of verdicts and insulating the jury from outside influences." Warger, 574 U.S., at ----, 135 S.Ct., at 526.
II
A
Recognizing the importance of Rule 606(b), this Court has twice rebuffed efforts to create a Sixth Amendment exception-first in Tanner and then, just two Terms ago, in Warger .
The Tanner petitioners were convicted of committing mail fraud and conspiring to defraud the United States. 483 U.S., at 109-110, 112-113, 107 S.Ct. 2739. After the trial, two jurors came forward with disturbing stories of juror misconduct. One claimed that several jurors "consumed alcohol during lunch breaks ... causing them to sleep through the afternoons." Id., at 113, 107 S.Ct. 2739. The second added that jurors also smoked marijuana and ingested cocaine during the trial. Id., at 115-116, 107 S.Ct. 2739. This Court held that evidence of this bacchanalia could properly be excluded under Rule 606(b). Id., at 127, 107 S.Ct. 2739.
The Court noted that "[s]ubstantial policy considerations support the common-law rule against the admission of jury testimony to impeach a verdict." Id., at 119, 107 S.Ct. 2739. While there is "little doubt that postverdict investigation into juror misconduct would in some instances lead to the invalidation of verdicts reached after irresponsible or improper juror behavior," the Court observed, it is "not at all clear ... that the jury system could survive such efforts to perfect it." Id ., at 120, 107 S.Ct. 2739. Allowing such post-verdict inquiries would "seriously disrupt the finality of the process." Ibid . It would also undermine "full and frank discussion in the jury room, jurors' willingness to return an unpopular verdict, and the community's trust in a system that relies on the decisions of laypeople." Id ., at 120-121, 107 S.Ct. 2739.
The Tanner petitioners, of course, had a Sixth Amendment right "to 'a tribunal both impartial and mentally competent to afford a hearing.' " Id ., at 126, 107 S.Ct. 2739 (quoting Jordan v. Massachusetts, 225 U.S. 167, 176, 32 S.Ct. 651, 56 L.Ed. 1038 (1912) ). The question, however, was whether they also had a right to an evidentiary hearing featuring "one particular kind of evidence inadmissible under the Federal Rules." 483 U.S., at 126-127, 107 S.Ct. 2739. Turning to that question, the Court noted again that "long-recognized and very substantial concerns support the protection of jury deliberations from intrusive inquiry." Id ., at 127, 107 S.Ct. 2739. By contrast, "[p]etitioners' Sixth Amendment interests in an unimpaired jury ... [were] protected by several aspects of the trial process." Ibid.
The Court identified four mechanisms that protect defendants' Sixth Amendment rights. First, jurors can be "examined during voir dire ." Ibid. Second, "during the trial the jury is observable by the court, by counsel, and by court personnel."