FRCP 48: Number of Jurors; Verdict; Polling
(a) Number of Jurors. A jury must begin with at least 6 and no more than 12 members, and each juror must participate in the verdict unless excused under Rule 47(c).
(b) Verdict. Unless the parties stipulate otherwise, the verdict must be unanimous and must be returned by a jury of at least 6 members.
(c) Polling. After a verdict is returned but before the jury is discharged, the court must on a party's request, or may on its own, poll the jurors individually. If the poll reveals a lack of unanimity or lack of assent by the number of jurors that the parties stipulated to, the court may direct the jury to deliberate further or may order a new trial.