Rule 502 The court on all proper occasions shall instruct the jury as to which party bears the burden of proof on each issue and as to whether that burden requ…

In a jury trial, the judge must explain to jurors which side has to prove each point in the case. The judge also has to explain how strong that proof needs to be.

There are different levels of proof depending on the type of case. In criminal cases, guilt must be proven "beyond a reasonable doubt," which is the highest standard. In civil cases, one side usually just needs to show their version is more likely true than not, which is called a "preponderance of the evidence." Sometimes a higher standard called "clear and convincing proof" is required for certain civil matters.

These instructions matter because they tell jurors exactly what they should be looking for when deciding whether someone has proven their case. Without knowing the right standard, jurors would have no way to judge whether the evidence is strong enough.