In the 1938 case of Pierre v. Louisiana, the U.S. Supreme Court ruled that a defendant's right to an impartial jury was violated when members of his race were systematically excluded from grand juries in Orleans Parish, Louisiana. The petitioner, Pierre, who was African American, had been indicted for murder by an all-white grand jury and subsequently convicted by a trial court. He appealed on grounds that black citizens were intentionally omitted from both petit and grand juries over many years due to their race - thus violating his Fourteenth Amendment rights to equal protection under law. The state argued it did not discriminate against blacks but rather used criteria such as property ownership or literacy tests which disproportionately affected them. However, the Supreme Court held that regardless of how discrimination occurred (whether directly or indirectly), if there is systematic exclusion based on race then it violates constitutional protections; hence they reversed Pierre’s conviction.

In the dissenting opinion for Pierre v. Louisiana, Justice McReynolds expressed concern over the majority's decision to overturn a conviction based on allegations of racial discrimination in jury selection. He argued that there was insufficient evidence to prove that black individuals were systematically excluded from serving on juries in Orleans Parish, where the trial took place. Furthermore, he pointed out that several black jurors had served in recent cases within this jurisdiction which contradicted claims of systematic exclusion. Justice McReynolds also noted that it is not unusual for certain groups to be underrepresented on juries due to various factors such as exemptions and disqualifications provided by law or personal choice not to serve when called upon. Therefore, mere statistical disparity does not necessarily indicate intentional discrimination against a particular race or group.