In Allen v. Hardy et al., the U.S. Supreme Court addressed whether an Illinois statute that allowed for peremptory challenges to exclude jurors based solely on their race was constitutional. The court found that such a practice violated the Equal Protection Clause of the Fourteenth Amendment, which guarantees all citizens equal protection under the law regardless of their race or ethnicity. However, it also ruled that this decision would not be applied retroactively to cases already decided before this ruling was made due to concerns about disrupting finality in criminal litigation and overburdening judicial resources with potential retrials.

In the dissenting opinion for Allen v. Hardy, Justice Brennan, joined by Justices Marshall and Blackmun, argued that the majority's decision to uphold Illinois' peremptory challenge system was inconsistent with previous rulings on equal protection rights. They contended that allowing prosecutors unlimited discretion in excluding potential jurors based on race perpetuated racial discrimination within the judicial process. The dissenters believed this practice violated defendants' constitutional right to a fair trial by an impartial jury and undermined public confidence in the justice system. They also disagreed with the majority's assertion that there were insufficient data showing systematic exclusion of black jurors; they pointed out numerous studies indicating otherwise. Finally, they criticized the court for failing to provide clear guidance on how lower courts should handle allegations of racial bias in juror selection.