Holding.
Yes, a trial on criminal charges before a five-member jury deprives the accused of the right to a trial by jury guaranteed by the Sixth and Fourteenth Amendments.
Reasoning.
The court considered (1) whether a reduction in the size of the state criminal trial jury inhibits the functioning of the jury as an institution to a significant degree and (2) if so, whether any state interest counterbalances and justifies the disruption so as to preserve its constitutionality. It answered “yes” to the first question, and pointed to recent empirical data suggesting that progressively smaller juries are less likely to foster effective group deliberation. Further, recent data raises doubts about the accuracy of the results achieved by smaller panels. The risk of convicting an innocent person rises as the size of the jury diminishes. As to the second question, it found no significant state advantage to reducing the number of jurors from six to five.
Concurring Decision.
Justice Powell
Justice Powell concurred in the agreement, but disagreed that every feature of jury trial practice must be the same in both federal and state courts, and expressed reservation with respect to the reliance on numerology derived from statistical studies.