[tzs]

The point of juries is to decide whether or not disputed facts are true. They don't need to know anything about the law because the jury instructions given to them by the court will deal with that.

The jury instructions essentially break the law down to essentially a flowchart, with the decision points being questions of whether or not some specific fact is true or not.

Both the prosecution and the defense will have geared the arguments and evidence they offered toward convincing the jury as to whether or not those specific facts or true.

[fakedang]

The point is that, regardless of how logical you want the jury to act, they will still act inherently with some bias because they are not trained in the law. While lawyers and members of the bar are also inherently prone to bias, they at least have some degree of knowledge on what evidence is admissible and what evidence should not be taken under consideration.