system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the point of a judge in countries where a jury decides if a prisoner is guilty or not?
gpt
Juries decide issues of *fact* (did such and such actually happen).  Judges decide issues of *law* (who is allowed to testify, what questions are allowed to be asked, who has the burden of proof, what facts must be proved to establish a particular crime).

So, for example, in an ordinary rape case, the judge might explain to the jury that they need to decide whether the victim actually consented to a sex act, but in a statutory rape case, the judge might explain to the jury that it doesn't matter whether the minor consented to sex or lied about their age.  These are points of law that you wouldn't expect an average juror to know going into the trial.