3.1 Evidence Must Be Confined to the Fact in Issue

The relevance's discipline: the proof confined to the facts in issue and the relevant facts (Unit 4's definitions) — the court's time and attention protected from the irrelevant. The operations: the pleadings' definition of the issues (the civil case's scope); the charge's frame (the criminal case's scope); the court's exclusion of collateral matters (the wandering testimony's control); the discretionary exceptions (the background-and-context evidence — the story's necessary scene). The principle's twin justifications: efficiency (the trial's economy) and fairness (the parties' protection from surprise and smearing).