jury as understood and applied at common law, and includes all the essential elements as they were recognized in this country and England when the Constitution was adopted." Therefore, it was held that juries had to be composed of twelve persons and that verdicts had to be unanimous, as was customary in England. When, under the Fourteenth Amendment, the Supreme Court extended the right to a trial by jury to defendants in state courts, it re-examined some of the standards. It has been held that twelve came to be the number of jurors by "historical accident", and that a jury of six would be sufficient, but anything less would deprive the defendant of a right to trial by jury. In Ramos v. Louisiana (2020), the Court ruled that the Sixth Amendment mandates unanimity in all federal and state criminal jury trials. Impartiality The Sixth Amendment requires juries to be impartial. Impartiality has been interpreted as requiring individual jurors to be unbiased. At voir dire, each side may question potential jurors to determine any bias, and challenge them if the same is found; the court determines the validity of these challenges for cause. Defendants may not challenge a conviction because a challenge for cause was denied incorrectly if they had the opportunity to use peremptory challenges. In Peña-Rodriguez v. Colorado (2017), the Supreme Court ruled that the Sixth Amendment requires a court in a criminal trial to investigate whether a jury's guilty verdict was based on racial bias. For a guilty verdict to be set aside based on the racial bias of a juror, the defendant must prove that the racial bias "was a significant motivating factor in the juror's vote to convict". Venire of juries Another factor in determining the impartiality of the jury is the nature of the panel, or venire, from which the jurors are selected. Venires must represent a fair cross-section of the community; the defendant might establish that the requirement was violated by showing that the allegedly excluded group is a "distinctive" one in the community, that the representation of such a group in venires is unreasonable and unfair in regard to the number of persons belonging to such a group, and that the under-representation is caused by a systematic exclusion in the selection process. Thus, in Taylor v. Louisiana, , the Supreme Court invalidated a state law that exempted women who had not made a