Rule 210 “Relevant evidence” means evidence, including evidence relevant to the credibility of a witness or hearsay declarant, having any tendency in reason to…

Evidence is only useful in court if it actually helps prove or disprove something that matters to the case. This is called "relevant evidence."

The bar for relevance is not very high. If a piece of evidence makes some disputed fact even slightly more or less likely to be true, it counts as relevant. This includes evidence that shows whether a witness is telling the truth or lying.

If evidence has nothing to do with the facts being argued in the case, a judge can keep it out of court. The key question is always whether the evidence connects to something that actually affects the outcome of the case.