Final answer:
In a capital criminal case, a defendant is tried by a jury of 12 jurors, all of whom must unanimously agree to render a verdict.
Step-by-step explanation:
In a capital criminal case, the defendant is tried by a jury typically consisting of 12 jurors. For the defendant to be convicted or acquitted, all jurors must reach a unanimous decision and concur to render a verdict. This means that all 12 jurors must agree on whether the defendant is guilty or not guilty. The requirement of unanimity serves to ensure a fair trial and is a fundamental aspect of the American legal system.