which amendment allows citizens to have a trial by jury
It has been held that twelve came to be the number of jurors by historical accident, and that a jury of six would be sufficient, but anything less would deprive the defendant of a right to trial by jury. The Sixth Amendment mandates unanimity in a federal jury trial. However, the Supreme Court has ruled that the Due Process Clause of the Fourteenth Amendment, while requiring states to provide jury trials for serious crimes, does not incorporate all the elements of a jury trial within the meaning of the Sixth Amendment.