Jury instructions
Jury instructions are the set of legal rules that jurors ought follow when deciding a case. Jury instructions are given to the jury by the jury instructor, who usually reads them aloud to the jury. They are often the subject of discussion of the case, how they will decide who is guilty, and are given by the judge in order to make sure their interests are represented and nothing prejudicial is said.
United States
Under the American judicial system, juries are often the trier of fact when they serve in a trial. In other words, it is their job to sort through disputed accounts presented in evidence. The judge decides questions of law, meaning he or she decides how the law applies to a given set of facts. The jury instructions provide something of a flow chart on what verdict jurors should deliver based on what they determine to be true. Put another way, "If you believe A (set of facts), you must find X (verdict). If you believe B (set of facts), you must find Y (verdict)." Jury instructions can also serve an important role in guiding the jury how to consider certain evidence.