Rule 402 General Admissibility of Relevant Evidence

If evidence actually matters to the case, the court will normally allow it. This rule says that relevant evidence gets admitted unless some other law or rule says it can't come in. That "other law" could be the Covenant that created the Commonwealth, the U.S. Constitution, the Commonwealth Constitution, a Commonwealth statute, these evidence rules, or other rules the Commonwealth Supreme Court has set up.

On the flip side, if evidence has nothing to do with the case, the court won't let it in at all. This keeps trials focused on facts that actually help decide what happened, instead of letting in random information that doesn't connect to the real questions being argued.