The Supreme Court on Monday ruled that defendants in criminal trials can only be convicted by a unanimous jury, striking down a scheme that has been rejected by every state except one. The court said in a divided opinion that the Constitution requires agreement among all members of a jury in order to impose a guilty verdict. "Wherever we might look to determine what the term 'trial by an impartial jury trial' meant at the time of the Sixth Amendment’s adoption—whether it’s the common law, state practices in the founding era, or opinions and treatises written soon afterward—the answer is...