> Currently, trial by jury means that a person on trial is judged by his/her peers.
Uh, no it doesn't. You watch too much tv and don't read enough books on the topic you are asking about.
> Why do you think it is that jurors make decisions based on personal expressions made by the person on trial?
Because they are instructed to make their decision solely on the basis of the evidence in the courtroom, and not on anything else they may have heard or seen about the case.
> Is that what the goal is from the first place?
Of course.
> If so, have the people on the juror panel been properly trained to interpret facial and body expressions?
No training is necessary. Voir dire takes care of it.
> Is it really more practical for the jury to make a decision based on physical appearance rather than evaluating the facts in written form?
Jurors are instructed to consider all of the evidence before them, nothing more and nothing less.
> Do you think that the reason why a jury doesn't perform its evaluation by written facts is because the process of sorting through the facts is similar to word problem and critical thinking skills that many average people lack?
No, that is nonsense. the system has been this way since the days of the Magna Carta. Evidence comes in many forms, written an otherwise. Not all "otherwise" evidence can be reduced to writing, and of those that can be, not all of it is universally objective.
Which is why we have an adversarial system. If the defendant presents evidence that harms the case, his or her attorney has an ethical obligation to present that side of the case in the best light he or she can.
> If so, why would anyone want those people to be deciding on the fate of their judgment?
You have a better solution?
In any case,m "ate" is not decided. There are always appeals available if there is an error of law, or for other reasons if the trila was not fairly decided.
> I believe that trial by jury should separate the person on trial from the facts revolving around the case being examined.
I don't even know what that means? The person should not be allowed to be at his or her trial so the jury can't see him or her?
> Why isn't such a system encouraged(facts including prior records either innocent or guilty)?
It is encouraged already. Evidence relevant to the charged crime is presented, and nothing else, in order to avoid prejudicing the jury. The adversary system allows trained advocates to persuade as needed, to have a say in who the jurors are, to offer evidence, to cross examine, and to speak to the jury directly in order to persuade, and to appeal.
What more do you want exactly?