The major disadvantage of have a trial by jury is that people tend to bring their own experiences and prejudices. Take the movie Twelve Angry Men, for instance. One of the jurors had a prejudice against people from slums. This prevented the man from seeing reason, so he stubbornly voted guilty, until the other jurors finally broke through to him. The defendant could have been sentenced to death because of one man's biased beliefs.

The advantage of having a trial by jury allows a sort of "second trial." For example, in the movie Twelve Angry Men, every single jury member voted guilty, except for one. The other eleven men demanded his reasons for voting Not Guilty, and he gave them. In the end, they voted Not Guilty unanimously. Now, the defendant in question was charged with murder, to which the penalty was death by electrocution. However, the evidence, which most of the jury members did not question, was not as sound as they thought, and the man that voted Not guilty showed them that. If the defendant hadn't had a jury, then he would have been sentenced to death, whether he was guilty or not, due to the meager and circumstantial evidence.