In Apodaca v. Oregon (1972), the Supreme Court held that the Sixth Amendment requires unanimity for a verdict -- but that the Fourteenth Amendment does not carry this rule over to the states, and that even 9-3 verdicts are constitutionally permissible. The Jury Trial Clause is thus the one Bill of Rights clause that is neither completely incorporated against the states via the Fourteenth Amendment, nor completely not incorporated. (Recall that the Bill of Rights originally applied only to the federal government, and has been applied to the states only through the Fourteenth Amendment.)

Interestingly, Apodaca was a 4-1-4 decision, in which both of the groups of 4 Justices took the view that the rule should be the same for federal and state trials. Only one Justice, Lewis Powell, believed that the rule should differ; but since he was the swing vote, his position became the law. To this day, the same two states that were involved in Apodaca and its companion case -- Oregon and Louisiana -- provide for nonunanimous juries. SCOTUSblog reports that the Court is about to consider a certiorari petition in Lee v. Louisiana asking the Justices to reconsider the question. The odds are much against such reconsideration, because the Justices rarely overrule their precedents (they do so sometimes, and the cases draw a lot of attention, but such overrulings are nonetheless rare). Still, this seems -- at least at this stage -- like the classic original meaning vs. precedent argument, made to a court that has shown a great deal of interest in original meaning. And in my view the petition (which is much worth reading) makes a pretty powerful argument why this particular precedent deserves less respect than many other precedents might. In any case, indeed looks like a "petition[] to watch," in SCOTUSblog's words.