 Because the fact of a prior felony conviction was an element of the crime of being a felon in possession of a firearm, the Court reasoned that the record of Old Chief's prior conviction was relevant under Rule 401.Hence, if "relevant evidence is inadmissible in the presence of other evidence related to it, its exclusion must rest not on the ground that the other evidence has rendered it "irrelevant," but on its character as unfairly prejudicial, cumulative or the like, its relevance notwithstanding.