In Colgrove v. Battin (1973), the Supreme Court ruled 5–4 that a six-person jury in a federal civil trial satisfies the Seventh Amendment’s guarantee of the right to a jury trial.1Justia. Colgrove v. Battin Justice Brennan’s majority opinion concluded that the amendment preserves the essential function of the jury, not the twelve-member panel size that happened to prevail at common law in 1791. The decision cleared the way for federal district courts to seat civil juries of fewer than twelve, and most now do.
How the Case Reached the Supreme Court
The United States District Court for the District of Montana adopted Local Rule 13(d)(1), requiring all civil juries in the district to consist of six members.2Legal Information Institute. Colgrove v. Battin When Judge James F. Battin scheduled the petitioner’s diversity case for trial before a six-person jury under that rule, Colgrove objected and sought a writ of mandamus from the Ninth Circuit to order a twelve-member panel.
He argued the local rule violated the Seventh Amendment, conflicted with the Rules Enabling Act (28 U.S.C. § 2072), and clashed with Federal Rule of Civil Procedure 48, which at the time addressed parties stipulating to fewer than twelve jurors. The Ninth Circuit denied relief. The Supreme Court granted review.
The Majority’s Reasoning
Justice Brennan, joined by Chief Justice Burger and Justices White, Blackmun, and Rehnquist, applied a functional test. The question was not whether twelve was the traditional number but whether a six-person jury could still do the jury’s job: applying community judgment to disputed facts.1Justia. Colgrove v. Battin
The Court answered yes, drawing heavily on Williams v. Florida, the 1970 decision upholding six-person juries in state criminal trials under the Sixth Amendment. Williams had described the twelve-member jury as a “historically accidental figure” the Framers never intended to constitutionalize, and the Colgrove majority carried that reasoning into the Seventh Amendment context.3Justia. Williams v. Florida The Seventh Amendment, on this view, preserves the substance of the common-law jury right, not every procedural feature attached to it in 1791.
The Court also pointed to empirical studies that, in its view, showed six-person juries produced outcomes comparable to twelve-member panels. That reliance became one of the decision’s most contested elements.
On the statutory argument, the Court found the Rules Enabling Act’s protection of the jury right “coextensive” with the Seventh Amendment itself. Because a six-person jury satisfied the Constitution, it satisfied the statute too.
The Dissents
Four justices dissented in three separate opinions, and the split matters because they attacked the result on different grounds.
Justice Marshall, joined by Justice Stewart, argued that the Seventh Amendment adopted the common-law jury rules as they stood in 1791, and the twelve-member panel was a “substantial and essential feature” of that right rather than a disposable detail.1Justia. Colgrove v. Battin Jury composition, he wrote, is a matter of definition, not something to be tested empirically and adjusted based on measured outcomes. Marshall also pressed the procedural point: Rule 48 gave parties a mechanism to stipulate to fewer than twelve jurors, and that provision would have no work to do if courts could impose smaller juries unilaterally.
Justice Douglas, joined by Justice Powell, focused on that same conflict between the local rule and Rule 48. Because Rule 48 treated twelve as the default, a local rule eliminating that default without party consent exceeded the district court’s authority. Justice Powell also filed a short separate dissent agreeing with Douglas on the procedural incompatibility, which let him avoid reaching the constitutional question.
The Empirical Evidence Problem
The majority cited four empirical studies as “convincing” evidence that six-person juries perform as well as twelve-member panels. Researchers who later reexamined those studies found significant methodological problems. Writing in the University of Michigan Journal of Law Reform, Shari Seidman Diamond demonstrated that none of the four studies actually provided valid data on whether jury size affects trial outcomes, and that the original reports omitted information that would have changed the conclusions.
Later research suggested that smaller juries are less representative of the community, less likely to recall evidence accurately during deliberation, and more likely to produce inconsistent verdicts. The constitutional holding rests on its own doctrinal logic, but the empirical reassurance the Court offered alongside it has not aged well. The Court acknowledged some of these concerns five years later in Ballew v. Georgia.
Ballew v. Georgia and the Constitutional Floor
In 1978, a unanimous Court held in Ballew v. Georgia that a jury of fewer than six members violates the right to trial by jury.4Justia. Ballew v. Georgia The case involved a Georgia law allowing five-person juries for certain criminal offenses. Justice Blackmun’s opinion reviewed the post-Williams research on jury size and concluded that reducing a panel below six “seriously impaired” the jury’s ability to represent the community and reach reliable verdicts.
The Court acknowledged it could not “discern a clear line between six members and five,” but treated the fundamental importance of jury trials as reason enough to draw the line there. Read together, Colgrove and Ballew bracket the permissible range: twelve is not required, and six is the floor.
What Colgrove Means for Federal Civil Juries Today
The current version of Federal Rule of Civil Procedure 48, amended in 1991, reflects the post-Colgrove landscape. A federal civil jury must begin with at least six and no more than twelve members, each juror participating in the verdict unless excused. The verdict must be unanimous and returned by at least six jurors, unless the parties stipulate otherwise.5Legal Information Institute. Rule 48 – Number of Jurors; Verdict; Polling
The 1991 amendment codified the range that Colgrove and Ballew had established through constitutional interpretation, and it resolved the procedural conflict the dissenters flagged by writing the six-to-twelve range directly into the rule. The current version of § 2072 no longer contains the specific jury-preservation language at issue in Colgrove; it now provides that federal procedural rules “shall not abridge, enlarge or modify any substantive right.”6Office of the Law Revision Counsel. 28 USC 2072 In practice, most federal districts now seat civil juries of six to eight members, making the twelve-person civil jury the exception rather than the rule.