The jury system is a system in which the verdict in a legal case is decided by a group of people on the basis of evidence submitted to them in court.
There is a jury in To Kill A Mockingbird during the Tom Robinson case. The 12 jury members were all white men, which meant they were all biased towards Tom Robinson because he was African American.
The jury system is still used today and plays a big role in trials. This is what they look like today, with all mixed races and both genders, so that the verdict is fair.
The jury system is used by common law countries only. It began in Britain during the Norman Conquest. It has continued to play a major role in trials, and is used mostly in America.
In To Kill a Mockingbird the jury is all white men most of the time. Being in a small town of course you do get used more than once, and it will be mostly white males since back then the males were "more superior" and the whites were more trust worthy. The problem with this though is that all of the men were biased towards Tom, or any other African American.
Now a days the jury system is chosen at random, and chosen between anyone over 18 with a drivers license. When the jury comes the two lawyers ask the jury if anyone in the jury knows the lawyers, defendant, victim or any other witnesses. If the person does know anyone of them then they say yes, but if they don't talk as much, even if they do know each other then they can continue to be a juror. But if they do keep in touch or know each other well then they will be taken off. The point of this step is to make sure they won't talk outside of court about it or be biased towards the other person. You can also be taken off the jury if you have medical problems, and you are paid to do it.