Williams v. Florida

Florida's rules required a defendant planning an alibi defense to disclose to the prosecution, before trial, where he claimed to have been and his alibi witnesses' names and addresses. Before his robbery trial, Williams (defendant) moved to be excused from the rule as compelled self-incrimination, and separately moved for a twelve-person jury instead of the six-person jury Florida used in noncapital cases; both motions were denied. Williams complied, named his alibi witness, and was convicted; the appellate court affirmed, and the Supreme Court granted certiorari.

Whether a state may require a defendant to give pretrial notice of an alibi defense and disclose alibi witnesses consistent with the Fifth and Fourteenth Amendments, and whether the Sixth Amendment requires a jury of exactly twelve.